/*
* Prune and repair fragmentation in the specified page.
*
* Caller must have pin and buffer cleanup lock on the page.
*
* OldestXmin is the cutoff XID used to distinguish whether tuples are DEAD
* or RECENTLY_DEAD (see HeapTupleSatisfiesVacuum).
*
* If report_stats is true then we send the number of reclaimed heap-only
* tuples to pgstats. (This must be FALSE during vacuum, since vacuum will
* send its own new total to pgstats, and we don't want this delta applied
* on top of that.)
*
* Returns the number of tuples deleted from the page and sets
* latestRemovedXid.
*/
int
heap_page_prune(Relation relation, Buffer buffer, TransactionId OldestXmin,
bool report_stats, TransactionId *latestRemovedXid)
{
int ndeleted = 0;
Page page = BufferGetPage(buffer);
OffsetNumber offnum,
maxoff;
PruneState prstate;
/*
* Our strategy is to scan the page and make lists of items to change,
* then apply the changes within a critical section. This keeps as much
* logic as possible out of the critical section, and also ensures that
* WAL replay will work the same as the normal case.
*
* First, initialize the new pd_prune_xid value to zero (indicating no
* prunable tuples). If we find any tuples which may soon become
* prunable, we will save the lowest relevant XID in new_prune_xid. Also
* initialize the rest of our working state.
*/
prstate.new_prune_xid = InvalidTransactionId;
prstate.latestRemovedXid = InvalidTransactionId;
prstate.nredirected = prstate.ndead = prstate.nunused = 0;
memset(prstate.marked, 0, sizeof(prstate.marked));
/* Scan the page */
maxoff = PageGetMaxOffsetNumber(page);
for (offnum = FirstOffsetNumber;
offnum <= maxoff;
offnum = OffsetNumberNext(offnum))
{
ItemId itemid;
/* Ignore items already processed as part of an earlier chain */
if (prstate.marked[offnum])
continue;
/* Nothing to do if slot is empty or already dead */
itemid = PageGetItemId(page, offnum);
if (!ItemIdIsUsed(itemid) || ItemIdIsDead(itemid))
continue;
/* Process this item or chain of items */
ndeleted += heap_prune_chain(relation, buffer, offnum,
OldestXmin,
&prstate);
}
/* Any error while applying the changes is critical */
START_CRIT_SECTION();
/* Have we found any prunable items? */
if (prstate.nredirected > 0 || prstate.ndead > 0 || prstate.nunused > 0)
{
/*
* Apply the planned item changes, then repair page fragmentation, and
* update the page's hint bit about whether it has free line pointers.
*/
heap_page_prune_execute(buffer,
prstate.redirected, prstate.nredirected,
prstate.nowdead, prstate.ndead,
prstate.nowunused, prstate.nunused);
/*
* Update the page's pd_prune_xid field to either zero, or the lowest
* XID of any soon-prunable tuple.
*/
((PageHeader) page)->pd_prune_xid = prstate.new_prune_xid;
/*
* Also clear the "page is full" flag, since there's no point in
* repeating the prune/defrag process until something else happens to
* the page.
*/
PageClearFull(page);
MarkBufferDirty(buffer);
/*
* Emit a WAL HEAP_CLEAN record showing what we did
*/
if (RelationNeedsWAL(relation))
{
XLogRecPtr recptr;
recptr = log_heap_clean(relation, buffer,
prstate.redirected, prstate.nredirected,
prstate.nowdead, prstate.ndead,
prstate.nowunused, prstate.nunused,
prstate.latestRemovedXid);
PageSetLSN(BufferGetPage(buffer), recptr);
PageSetTLI(BufferGetPage(buffer), ThisTimeLineID);
}
}
else
{
/*
* If we didn't prune anything, but have found a new value for the
* pd_prune_xid field, update it and mark the buffer dirty. This is
* treated as a non-WAL-logged hint.
*
* Also clear the "page is full" flag if it is set, since there's no
* point in repeating the prune/defrag process until something else
* happens to the page.
*/
if (((PageHeader) page)->pd_prune_xid != prstate.new_prune_xid ||
PageIsFull(page))
{
((PageHeader) page)->pd_prune_xid = prstate.new_prune_xid;
PageClearFull(page);
SetBufferCommitInfoNeedsSave(buffer);
}
}
END_CRIT_SECTION();
/*
* If requested, report the number of tuples reclaimed to pgstats. This is
* ndeleted minus ndead, because we don't want to count a now-DEAD root
* item as a deletion for this purpose.
*/
if (report_stats && ndeleted > prstate.ndead)
pgstat_update_heap_dead_tuples(relation, ndeleted - prstate.ndead);
*latestRemovedXid = prstate.latestRemovedXid;
/*
* XXX Should we update the FSM information of this page ?
*
* There are two schools of thought here. We may not want to update FSM
* information so that the page is not used for unrelated UPDATEs/INSERTs
* and any free space in this page will remain available for further
* UPDATEs in *this* page, thus improving chances for doing HOT updates.
*
* But for a large table and where a page does not receive further UPDATEs
* for a long time, we might waste this space by not updating the FSM
* information. The relation may get extended and fragmented further.
*
* One possibility is to leave "fillfactor" worth of space in this page
* and update FSM with the remaining space.
*/
return ndeleted;
}
/*
* Traverse the tree to find path from root page to specified "child" block.
*
* returns a new insertion stack, starting from the parent of "child", up
* to the root. *downlinkoffnum is set to the offset of the downlink in the
* direct parent of child.
*
* To prevent deadlocks, this should lock only one page at a time.
*/
static GISTInsertStack *
gistFindPath(Relation r, BlockNumber child, OffsetNumber *downlinkoffnum)
{
Page page;
Buffer buffer;
OffsetNumber i,
maxoff;
ItemId iid;
IndexTuple idxtuple;
List *fifo;
GISTInsertStack *top,
*ptr;
BlockNumber blkno;
top = (GISTInsertStack *) palloc0(sizeof(GISTInsertStack));
top->blkno = GIST_ROOT_BLKNO;
top->downlinkoffnum = InvalidOffsetNumber;
fifo = list_make1(top);
while (fifo != NIL)
{
/* Get next page to visit */
top = linitial(fifo);
fifo = list_delete_first(fifo);
buffer = ReadBuffer(r, top->blkno);
LockBuffer(buffer, GIST_SHARE);
gistcheckpage(r, buffer);
page = (Page) BufferGetPage(buffer);
if (GistPageIsLeaf(page))
{
/*
* Because we scan the index top-down, all the rest of the pages
* in the queue must be leaf pages as well.
*/
UnlockReleaseBuffer(buffer);
break;
}
top->lsn = PageGetLSN(page);
/*
* If F_FOLLOW_RIGHT is set, the page to the right doesn't have a
* downlink. This should not normally happen..
*/
if (GistFollowRight(page))
elog(ERROR, "concurrent GiST page split was incomplete");
if (top->parent && top->parent->lsn < GistPageGetNSN(page) &&
GistPageGetOpaque(page)->rightlink != InvalidBlockNumber /* sanity check */ )
{
/*
* Page was split while we looked elsewhere. We didn't see the
* downlink to the right page when we scanned the parent, so add
* it to the queue now.
*
* Put the right page ahead of the queue, so that we visit it
* next. That's important, because if this is the lowest internal
* level, just above leaves, we might already have queued up some
* leaf pages, and we assume that there can't be any non-leaf
* pages behind leaf pages.
*/
ptr = (GISTInsertStack *) palloc0(sizeof(GISTInsertStack));
ptr->blkno = GistPageGetOpaque(page)->rightlink;
ptr->downlinkoffnum = InvalidOffsetNumber;
ptr->parent = top->parent;
fifo = lcons(ptr, fifo);
}
maxoff = PageGetMaxOffsetNumber(page);
for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
{
iid = PageGetItemId(page, i);
idxtuple = (IndexTuple) PageGetItem(page, iid);
blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
if (blkno == child)
{
/* Found it! */
UnlockReleaseBuffer(buffer);
*downlinkoffnum = i;
return top;
}
else
{
/* Append this child to the list of pages to visit later */
ptr = (GISTInsertStack *) palloc0(sizeof(GISTInsertStack));
ptr->blkno = blkno;
ptr->downlinkoffnum = i;
ptr->parent = top;
fifo = lappend(fifo, ptr);
}
}
UnlockReleaseBuffer(buffer);
}
elog(ERROR, "failed to re-find parent of a page in index \"%s\", block %u",
RelationGetRelationName(r), child);
return NULL; /* keep compiler quiet */
}
/*
* Bulk deletion of all index entries pointing to a set of heap tuples and
* check invalid tuples left after upgrade.
* The set of target tuples is specified via a callback routine that tells
* whether any given heap tuple (identified by ItemPointer) is being deleted.
*
* Result: a palloc'd struct containing statistical info for VACUUM displays.
*/
Datum
gistbulkdelete(PG_FUNCTION_ARGS)
{
IndexVacuumInfo *info = (IndexVacuumInfo *) PG_GETARG_POINTER(0);
IndexBulkDeleteResult *stats = (IndexBulkDeleteResult *) PG_GETARG_POINTER(1);
IndexBulkDeleteCallback callback = (IndexBulkDeleteCallback) PG_GETARG_POINTER(2);
void *callback_state = (void *) PG_GETARG_POINTER(3);
Relation rel = info->index;
GistBDItem *stack,
*ptr;
/* first time through? */
if (stats == NULL)
stats = (IndexBulkDeleteResult *) palloc0(sizeof(IndexBulkDeleteResult));
/* we'll re-count the tuples each time */
stats->estimated_count = false;
stats->num_index_tuples = 0;
stack = (GistBDItem *) palloc0(sizeof(GistBDItem));
stack->blkno = GIST_ROOT_BLKNO;
while (stack)
{
Buffer buffer;
Page page;
OffsetNumber i,
maxoff;
IndexTuple idxtuple;
ItemId iid;
buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
RBM_NORMAL, info->strategy);
LockBuffer(buffer, GIST_SHARE);
gistcheckpage(rel, buffer);
page = (Page) BufferGetPage(buffer);
if (GistPageIsLeaf(page))
{
OffsetNumber todelete[MaxOffsetNumber];
int ntodelete = 0;
LockBuffer(buffer, GIST_UNLOCK);
LockBuffer(buffer, GIST_EXCLUSIVE);
page = (Page) BufferGetPage(buffer);
if (stack->blkno == GIST_ROOT_BLKNO && !GistPageIsLeaf(page))
{
/* only the root can become non-leaf during relock */
UnlockReleaseBuffer(buffer);
/* one more check */
continue;
}
/*
* check for split proceeded after look at parent, we should check
* it after relock
*/
pushStackIfSplited(page, stack);
/*
* Remove deletable tuples from page
*/
maxoff = PageGetMaxOffsetNumber(page);
for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
{
iid = PageGetItemId(page, i);
idxtuple = (IndexTuple) PageGetItem(page, iid);
if (callback(&(idxtuple->t_tid), callback_state))
{
todelete[ntodelete] = i - ntodelete;
ntodelete++;
stats->tuples_removed += 1;
}
else
stats->num_index_tuples += 1;
}
if (ntodelete)
{
START_CRIT_SECTION();
MarkBufferDirty(buffer);
for (i = 0; i < ntodelete; i++)
PageIndexTupleDelete(page, todelete[i]);
GistMarkTuplesDeleted(page);
if (RelationNeedsWAL(rel))
{
XLogRecPtr recptr;
recptr = gistXLogUpdate(rel->rd_node, buffer,
todelete, ntodelete,
NULL, 0, InvalidBuffer);
PageSetLSN(page, recptr);
PageSetTLI(page, ThisTimeLineID);
}
else
PageSetLSN(page, GetXLogRecPtrForTemp());
END_CRIT_SECTION();
}
}
else
{
/* check for split proceeded after look at parent */
pushStackIfSplited(page, stack);
maxoff = PageGetMaxOffsetNumber(page);
for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
{
iid = PageGetItemId(page, i);
idxtuple = (IndexTuple) PageGetItem(page, iid);
ptr = (GistBDItem *) palloc(sizeof(GistBDItem));
ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
ptr->parentlsn = PageGetLSN(page);
ptr->next = stack->next;
stack->next = ptr;
if (GistTupleIsInvalid(idxtuple))
ereport(LOG,
(errmsg("index \"%s\" contains an inner tuple marked as invalid",
RelationGetRelationName(rel)),
errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
errhint("Please REINDEX it.")));
}
}
UnlockReleaseBuffer(buffer);
ptr = stack->next;
pfree(stack);
stack = ptr;
vacuum_delay_point();
}
PG_RETURN_POINTER(stats);
}
/* ----------------------------------------------------------------
* BitmapHeapNext
*
* Retrieve next tuple from the BitmapHeapScan node's currentRelation
* ----------------------------------------------------------------
*/
static TupleTableSlot *
BitmapHeapNext(BitmapHeapScanState *node)
{
ExprContext *econtext;
HeapScanDesc scan;
TIDBitmap *tbm;
TBMIterator *tbmiterator = NULL;
TBMSharedIterator *shared_tbmiterator = NULL;
TBMIterateResult *tbmres;
OffsetNumber targoffset;
TupleTableSlot *slot;
ParallelBitmapHeapState *pstate = node->pstate;
dsa_area *dsa = node->ss.ps.state->es_query_dsa;
/*
* extract necessary information from index scan node
*/
econtext = node->ss.ps.ps_ExprContext;
slot = node->ss.ss_ScanTupleSlot;
scan = node->ss.ss_currentScanDesc;
tbm = node->tbm;
if (pstate == NULL)
tbmiterator = node->tbmiterator;
else
shared_tbmiterator = node->shared_tbmiterator;
tbmres = node->tbmres;
/*
* If we haven't yet performed the underlying index scan, do it, and begin
* the iteration over the bitmap.
*
* For prefetching, we use *two* iterators, one for the pages we are
* actually scanning and another that runs ahead of the first for
* prefetching. node->prefetch_pages tracks exactly how many pages ahead
* the prefetch iterator is. Also, node->prefetch_target tracks the
* desired prefetch distance, which starts small and increases up to the
* node->prefetch_maximum. This is to avoid doing a lot of prefetching in
* a scan that stops after a few tuples because of a LIMIT.
*/
if (!node->initialized)
{
if (!pstate)
{
tbm = (TIDBitmap *) MultiExecProcNode(outerPlanState(node));
if (!tbm || !IsA(tbm, TIDBitmap))
elog(ERROR, "unrecognized result from subplan");
node->tbm = tbm;
node->tbmiterator = tbmiterator = tbm_begin_iterate(tbm);
node->tbmres = tbmres = NULL;
#ifdef USE_PREFETCH
if (node->prefetch_maximum > 0)
{
node->prefetch_iterator = tbm_begin_iterate(tbm);
node->prefetch_pages = 0;
node->prefetch_target = -1;
}
#endif /* USE_PREFETCH */
}
else
{
/*
* The leader will immediately come out of the function, but
* others will be blocked until leader populates the TBM and wakes
* them up.
*/
if (BitmapShouldInitializeSharedState(pstate))
{
tbm = (TIDBitmap *) MultiExecProcNode(outerPlanState(node));
if (!tbm || !IsA(tbm, TIDBitmap))
elog(ERROR, "unrecognized result from subplan");
node->tbm = tbm;
/*
* Prepare to iterate over the TBM. This will return the
* dsa_pointer of the iterator state which will be used by
* multiple processes to iterate jointly.
*/
pstate->tbmiterator = tbm_prepare_shared_iterate(tbm);
#ifdef USE_PREFETCH
if (node->prefetch_maximum > 0)
{
pstate->prefetch_iterator =
tbm_prepare_shared_iterate(tbm);
/*
* We don't need the mutex here as we haven't yet woke up
* others.
*/
pstate->prefetch_pages = 0;
pstate->prefetch_target = -1;
}
#endif
/* We have initialized the shared state so wake up others. */
BitmapDoneInitializingSharedState(pstate);
}
/* Allocate a private iterator and attach the shared state to it */
node->shared_tbmiterator = shared_tbmiterator =
tbm_attach_shared_iterate(dsa, pstate->tbmiterator);
node->tbmres = tbmres = NULL;
#ifdef USE_PREFETCH
if (node->prefetch_maximum > 0)
{
node->shared_prefetch_iterator =
tbm_attach_shared_iterate(dsa, pstate->prefetch_iterator);
}
#endif /* USE_PREFETCH */
}
node->initialized = true;
}
for (;;)
{
Page dp;
ItemId lp;
/*
* Get next page of results if needed
*/
if (tbmres == NULL)
{
if (!pstate)
node->tbmres = tbmres = tbm_iterate(tbmiterator);
else
node->tbmres = tbmres = tbm_shared_iterate(shared_tbmiterator);
if (tbmres == NULL)
{
/* no more entries in the bitmap */
break;
}
BitmapAdjustPrefetchIterator(node, tbmres);
/*
* Ignore any claimed entries past what we think is the end of the
* relation. (This is probably not necessary given that we got at
* least AccessShareLock on the table before performing any of the
* indexscans, but let's be safe.)
*/
if (tbmres->blockno >= scan->rs_nblocks)
{
node->tbmres = tbmres = NULL;
continue;
}
/*
* Fetch the current heap page and identify candidate tuples.
*/
bitgetpage(scan, tbmres);
if (tbmres->ntuples >= 0)
node->exact_pages++;
else
node->lossy_pages++;
/*
* Set rs_cindex to first slot to examine
*/
scan->rs_cindex = 0;
/* Adjust the prefetch target */
BitmapAdjustPrefetchTarget(node);
}
else
{
/*
* Continuing in previously obtained page; advance rs_cindex
*/
scan->rs_cindex++;
#ifdef USE_PREFETCH
/*
* Try to prefetch at least a few pages even before we get to the
* second page if we don't stop reading after the first tuple.
*/
if (!pstate)
{
if (node->prefetch_target < node->prefetch_maximum)
node->prefetch_target++;
}
else if (pstate->prefetch_target < node->prefetch_maximum)
{
/* take spinlock while updating shared state */
SpinLockAcquire(&pstate->mutex);
if (pstate->prefetch_target < node->prefetch_maximum)
pstate->prefetch_target++;
SpinLockRelease(&pstate->mutex);
}
#endif /* USE_PREFETCH */
}
/*
* Out of range? If so, nothing more to look at on this page
*/
if (scan->rs_cindex < 0 || scan->rs_cindex >= scan->rs_ntuples)
{
node->tbmres = tbmres = NULL;
continue;
}
/*
* We issue prefetch requests *after* fetching the current page to try
* to avoid having prefetching interfere with the main I/O. Also, this
* should happen only when we have determined there is still something
* to do on the current page, else we may uselessly prefetch the same
* page we are just about to request for real.
*/
BitmapPrefetch(node, scan);
/*
* Okay to fetch the tuple
*/
targoffset = scan->rs_vistuples[scan->rs_cindex];
dp = (Page) BufferGetPage(scan->rs_cbuf);
lp = PageGetItemId(dp, targoffset);
Assert(ItemIdIsNormal(lp));
scan->rs_ctup.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
scan->rs_ctup.t_len = ItemIdGetLength(lp);
scan->rs_ctup.t_tableOid = scan->rs_rd->rd_id;
ItemPointerSet(&scan->rs_ctup.t_self, tbmres->blockno, targoffset);
pgstat_count_heap_fetch(scan->rs_rd);
/*
* Set up the result slot to point to this tuple. Note that the slot
* acquires a pin on the buffer.
*/
ExecStoreTuple(&scan->rs_ctup,
slot,
scan->rs_cbuf,
false);
/*
* If we are using lossy info, we have to recheck the qual conditions
* at every tuple.
*/
if (tbmres->recheck)
{
econtext->ecxt_scantuple = slot;
ResetExprContext(econtext);
if (!ExecQual(node->bitmapqualorig, econtext))
{
/* Fails recheck, so drop it and loop back for another */
InstrCountFiltered2(node, 1);
ExecClearTuple(slot);
continue;
}
}
/* OK to return this tuple */
return slot;
}
/*
* if we get here it means we are at the end of the scan..
*/
return ExecClearTuple(slot);
}
/*
* _hash_step() -- step to the next valid item in a scan in the bucket.
*
* If no valid record exists in the requested direction, return
* false. Else, return true and set the hashso_curpos for the
* scan to the right thing.
*
* 'bufP' points to the current buffer, which is pinned and read-locked.
* On success exit, we have pin and read-lock on whichever page
* contains the right item; on failure, we have released all buffers.
*/
bool
_hash_step(IndexScanDesc scan, Buffer *bufP, ScanDirection dir)
{
Relation rel = scan->indexRelation;
HashScanOpaque so = (HashScanOpaque) scan->opaque;
ItemPointer current;
Buffer buf;
Page page;
HashPageOpaque opaque;
OffsetNumber maxoff;
OffsetNumber offnum;
BlockNumber blkno;
IndexTuple itup;
current = &(so->hashso_curpos);
buf = *bufP;
_hash_checkpage(rel, buf, LH_BUCKET_PAGE | LH_OVERFLOW_PAGE);
page = BufferGetPage(buf);
opaque = (HashPageOpaque) PageGetSpecialPointer(page);
/*
* If _hash_step is called from _hash_first, current will not be valid, so
* we can't dereference it. However, in that case, we presumably want to
* start at the beginning/end of the page...
*/
maxoff = PageGetMaxOffsetNumber(page);
if (ItemPointerIsValid(current))
offnum = ItemPointerGetOffsetNumber(current);
else
offnum = InvalidOffsetNumber;
/*
* 'offnum' now points to the last tuple we examined (if any).
*
* continue to step through tuples until: 1) we get to the end of the
* bucket chain or 2) we find a valid tuple.
*/
do
{
switch (dir)
{
case ForwardScanDirection:
if (offnum != InvalidOffsetNumber)
offnum = OffsetNumberNext(offnum); /* move forward */
else
{
/* new page, locate starting position by binary search */
offnum = _hash_binsearch(page, so->hashso_sk_hash);
}
for (;;)
{
/*
* check if we're still in the range of items with the
* target hash key
*/
if (offnum <= maxoff)
{
Assert(offnum >= FirstOffsetNumber);
itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, offnum));
if (so->hashso_sk_hash == _hash_get_indextuple_hashkey(itup))
break; /* yes, so exit for-loop */
}
/*
* ran off the end of this page, try the next
*/
_hash_readnext(rel, &buf, &page, &opaque);
if (BufferIsValid(buf))
{
maxoff = PageGetMaxOffsetNumber(page);
offnum = _hash_binsearch(page, so->hashso_sk_hash);
}
else
{
/* end of bucket */
itup = NULL;
break; /* exit for-loop */
}
}
break;
case BackwardScanDirection:
if (offnum != InvalidOffsetNumber)
offnum = OffsetNumberPrev(offnum); /* move back */
else
{
/* new page, locate starting position by binary search */
offnum = _hash_binsearch_last(page, so->hashso_sk_hash);
}
for (;;)
{
/*
* check if we're still in the range of items with the
* target hash key
*/
if (offnum >= FirstOffsetNumber)
{
Assert(offnum <= maxoff);
itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, offnum));
if (so->hashso_sk_hash == _hash_get_indextuple_hashkey(itup))
break; /* yes, so exit for-loop */
}
/*
* ran off the end of this page, try the next
*/
_hash_readprev(rel, &buf, &page, &opaque);
if (BufferIsValid(buf))
{
maxoff = PageGetMaxOffsetNumber(page);
offnum = _hash_binsearch_last(page, so->hashso_sk_hash);
}
else
{
/* end of bucket */
itup = NULL;
break; /* exit for-loop */
}
}
break;
default:
/* NoMovementScanDirection */
/* this should not be reached */
itup = NULL;
break;
}
if (itup == NULL)
{
/* we ran off the end of the bucket without finding a match */
*bufP = so->hashso_curbuf = InvalidBuffer;
ItemPointerSetInvalid(current);
return false;
}
/* check the tuple quals, loop around if not met */
} while (!_hash_checkqual(scan, itup));
/* if we made it to here, we've found a valid tuple */
blkno = BufferGetBlockNumber(buf);
*bufP = so->hashso_curbuf = buf;
ItemPointerSet(current, blkno, offnum);
return true;
}
/*
* Find correct tuple in non-leaf page. It supposed that
* page correctly chosen and searching value SHOULD be on page
*/
static BlockNumber
entryLocateEntry(GinBtree btree, GinBtreeStack *stack)
{
OffsetNumber low,
high,
maxoff;
IndexTuple itup = NULL;
int result;
Page page = BufferGetPage(stack->buffer);
Assert(!GinPageIsLeaf(page));
Assert(!GinPageIsData(page));
if (btree->fullScan)
{
stack->off = FirstOffsetNumber;
stack->predictNumber *= PageGetMaxOffsetNumber(page);
return btree->getLeftMostChild(btree, page);
}
low = FirstOffsetNumber;
maxoff = high = PageGetMaxOffsetNumber(page);
Assert(high >= low);
high++;
while (high > low)
{
OffsetNumber mid = low + ((high - low) / 2);
if (mid == maxoff && GinPageRightMost(page))
{
/* Right infinity */
result = -1;
}
else
{
OffsetNumber attnum;
Datum key;
GinNullCategory category;
itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, mid));
attnum = gintuple_get_attrnum(btree->ginstate, itup);
key = gintuple_get_key(btree->ginstate, itup, &category);
result = ginCompareAttEntries(btree->ginstate,
btree->entryAttnum,
btree->entryKey,
btree->entryCategory,
attnum, key, category);
}
if (result == 0)
{
stack->off = mid;
Assert(GinGetDownlink(itup) != GIN_ROOT_BLKNO);
return GinGetDownlink(itup);
}
else if (result > 0)
low = mid + 1;
else
high = mid;
}
Assert(high >= FirstOffsetNumber && high <= maxoff);
stack->off = high;
itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, high));
Assert(GinGetDownlink(itup) != GIN_ROOT_BLKNO);
return GinGetDownlink(itup);
}
/* ----------------
* index_getnext - get the next heap tuple from a scan
*
* The result is the next heap tuple satisfying the scan keys and the
* snapshot, or NULL if no more matching tuples exist. On success,
* the buffer containing the heap tuple is pinned (the pin will be dropped
* at the next index_getnext or index_endscan).
*
* Note: caller must check scan->xs_recheck, and perform rechecking of the
* scan keys if required. We do not do that here because we don't have
* enough information to do it efficiently in the general case.
* ----------------
*/
HeapTuple
index_getnext(IndexScanDesc scan, ScanDirection direction)
{
HeapTuple heapTuple = &scan->xs_ctup;
ItemPointer tid = &heapTuple->t_self;
FmgrInfo *procedure;
SCAN_CHECKS;
GET_SCAN_PROCEDURE(amgettuple);
Assert(TransactionIdIsValid(RecentGlobalXmin));
/*
* We always reset xs_hot_dead; if we are here then either we are just
* starting the scan, or we previously returned a visible tuple, and in
* either case it's inappropriate to kill the prior index entry.
*/
scan->xs_hot_dead = false;
for (;;)
{
OffsetNumber offnum;
bool at_chain_start;
Page dp;
if (scan->xs_next_hot != InvalidOffsetNumber)
{
/*
* We are resuming scan of a HOT chain after having returned an
* earlier member. Must still hold pin on current heap page.
*/
Assert(BufferIsValid(scan->xs_cbuf));
Assert(ItemPointerGetBlockNumber(tid) ==
BufferGetBlockNumber(scan->xs_cbuf));
Assert(TransactionIdIsValid(scan->xs_prev_xmax));
offnum = scan->xs_next_hot;
at_chain_start = false;
scan->xs_next_hot = InvalidOffsetNumber;
}
else
{
bool found;
Buffer prev_buf;
/*
* If we scanned a whole HOT chain and found only dead tuples,
* tell index AM to kill its entry for that TID. We do not do this
* when in recovery because it may violate MVCC to do so. see
* comments in RelationGetIndexScan().
*/
if (!scan->xactStartedInRecovery)
scan->kill_prior_tuple = scan->xs_hot_dead;
/*
* The AM's gettuple proc finds the next index entry matching the
* scan keys, and puts the TID in xs_ctup.t_self (ie, *tid). It
* should also set scan->xs_recheck, though we pay no attention to
* that here.
*/
found = DatumGetBool(FunctionCall2(procedure,
PointerGetDatum(scan),
Int32GetDatum(direction)));
/* Reset kill flag immediately for safety */
scan->kill_prior_tuple = false;
/* If we're out of index entries, break out of outer loop */
if (!found)
break;
pgstat_count_index_tuples(scan->indexRelation, 1);
/* Switch to correct buffer if we don't have it already */
prev_buf = scan->xs_cbuf;
scan->xs_cbuf = ReleaseAndReadBuffer(scan->xs_cbuf,
scan->heapRelation,
ItemPointerGetBlockNumber(tid));
/*
* Prune page, but only if we weren't already on this page
*/
if (prev_buf != scan->xs_cbuf)
heap_page_prune_opt(scan->heapRelation, scan->xs_cbuf,
RecentGlobalXmin);
/* Prepare to scan HOT chain starting at index-referenced offnum */
offnum = ItemPointerGetOffsetNumber(tid);
at_chain_start = true;
/* We don't know what the first tuple's xmin should be */
scan->xs_prev_xmax = InvalidTransactionId;
/* Initialize flag to detect if all entries are dead */
scan->xs_hot_dead = true;
}
/* Obtain share-lock on the buffer so we can examine visibility */
LockBuffer(scan->xs_cbuf, BUFFER_LOCK_SHARE);
dp = (Page) BufferGetPage(scan->xs_cbuf);
/* Scan through possible multiple members of HOT-chain */
for (;;)
{
ItemId lp;
ItemPointer ctid;
bool valid;
/* check for bogus TID */
if (offnum < FirstOffsetNumber ||
offnum > PageGetMaxOffsetNumber(dp))
break;
lp = PageGetItemId(dp, offnum);
/* check for unused, dead, or redirected items */
if (!ItemIdIsNormal(lp))
{
/* We should only see a redirect at start of chain */
if (ItemIdIsRedirected(lp) && at_chain_start)
{
/* Follow the redirect */
offnum = ItemIdGetRedirect(lp);
at_chain_start = false;
continue;
}
/* else must be end of chain */
break;
}
/*
* We must initialize all of *heapTuple (ie, scan->xs_ctup) since
* it is returned to the executor on success.
*/
heapTuple->t_data = (HeapTupleHeader) PageGetItem(dp, lp);
heapTuple->t_len = ItemIdGetLength(lp);
ItemPointerSetOffsetNumber(tid, offnum);
heapTuple->t_tableOid = RelationGetRelid(scan->heapRelation);
ctid = &heapTuple->t_data->t_ctid;
/*
* Shouldn't see a HEAP_ONLY tuple at chain start. (This test
* should be unnecessary, since the chain root can't be removed
* while we have pin on the index entry, but let's make it
* anyway.)
*/
if (at_chain_start && HeapTupleIsHeapOnly(heapTuple))
break;
/*
* The xmin should match the previous xmax value, else chain is
* broken. (Note: this test is not optional because it protects
* us against the case where the prior chain member's xmax aborted
* since we looked at it.)
*/
if (TransactionIdIsValid(scan->xs_prev_xmax) &&
!TransactionIdEquals(scan->xs_prev_xmax,
HeapTupleHeaderGetXmin(heapTuple->t_data)))
break;
/* If it's visible per the snapshot, we must return it */
valid = HeapTupleSatisfiesVisibility(heapTuple, scan->xs_snapshot,
scan->xs_cbuf);
CheckForSerializableConflictOut(valid, scan->heapRelation,
heapTuple, scan->xs_cbuf);
if (valid)
{
/*
* If the snapshot is MVCC, we know that it could accept at
* most one member of the HOT chain, so we can skip examining
* any more members. Otherwise, check for continuation of the
* HOT-chain, and set state for next time.
*/
if (IsMVCCSnapshot(scan->xs_snapshot)
&& !IsolationIsSerializable())
scan->xs_next_hot = InvalidOffsetNumber;
else if (HeapTupleIsHotUpdated(heapTuple))
{
Assert(ItemPointerGetBlockNumber(ctid) ==
ItemPointerGetBlockNumber(tid));
scan->xs_next_hot = ItemPointerGetOffsetNumber(ctid);
scan->xs_prev_xmax = HeapTupleHeaderGetXmax(heapTuple->t_data);
}
else
scan->xs_next_hot = InvalidOffsetNumber;
PredicateLockTuple(scan->heapRelation, heapTuple);
LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
pgstat_count_heap_fetch(scan->indexRelation);
return heapTuple;
}
/*
* If we can't see it, maybe no one else can either. Check to see
* if the tuple is dead to all transactions. If we find that all
* the tuples in the HOT chain are dead, we'll signal the index AM
* to not return that TID on future indexscans.
*/
if (scan->xs_hot_dead &&
HeapTupleSatisfiesVacuum(heapTuple->t_data, RecentGlobalXmin,
scan->xs_cbuf) != HEAPTUPLE_DEAD)
scan->xs_hot_dead = false;
/*
* Check to see if HOT chain continues past this tuple; if so
* fetch the next offnum (we don't bother storing it into
* xs_next_hot, but must store xs_prev_xmax), and loop around.
*/
if (HeapTupleIsHotUpdated(heapTuple))
{
Assert(ItemPointerGetBlockNumber(ctid) ==
ItemPointerGetBlockNumber(tid));
offnum = ItemPointerGetOffsetNumber(ctid);
at_chain_start = false;
scan->xs_prev_xmax = HeapTupleHeaderGetXmax(heapTuple->t_data);
}
else
break; /* end of chain */
} /* loop over a single HOT chain */
LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
/* Loop around to ask index AM for another TID */
scan->xs_next_hot = InvalidOffsetNumber;
}
/* Release any held pin on a heap page */
if (BufferIsValid(scan->xs_cbuf))
{
ReleaseBuffer(scan->xs_cbuf);
scan->xs_cbuf = InvalidBuffer;
}
return NULL; /* failure exit */
}
/*
* PageAddItem
*
* Add an item to a page. Return value is offset at which it was
* inserted, or InvalidOffsetNumber if there's not room to insert.
*
* If overwrite is true, we just store the item at the specified
* offsetNumber (which must be either a currently-unused item pointer,
* or one past the last existing item). Otherwise,
* if offsetNumber is valid and <= current max offset in the page,
* insert item into the array at that position by shuffling ItemId's
* down to make room.
* If offsetNumber is not valid, then assign one by finding the first
* one that is both unused and deallocated.
*
* If is_heap is true, we enforce that there can't be more than
* MaxHeapTuplesPerPage line pointers on the page.
*
* !!! EREPORT(ERROR) IS DISALLOWED HERE !!!
*/
OffsetNumber
PageAddItem(Page page,
Item item,
Size size,
OffsetNumber offsetNumber,
bool overwrite,
bool is_heap)
{
PageHeader phdr = (PageHeader) page;
Size alignedSize;
int lower;
int upper;
ItemId itemId;
OffsetNumber limit;
bool needshuffle = false;
/*
* Be wary about corrupted page pointers
*/
if (phdr->pd_lower < SizeOfPageHeaderData ||
phdr->pd_lower > phdr->pd_upper ||
phdr->pd_upper > phdr->pd_special ||
phdr->pd_special > BLCKSZ)
ereport(PANIC,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("corrupted page pointers: lower = %u, upper = %u, special = %u",
phdr->pd_lower, phdr->pd_upper, phdr->pd_special)));
/*
* Select offsetNumber to place the new item at
*/
limit = OffsetNumberNext(PageGetMaxOffsetNumber(page));
/* was offsetNumber passed in? */
if (OffsetNumberIsValid(offsetNumber))
{
/* yes, check it */
if (overwrite)
{
if (offsetNumber < limit)
{
itemId = PageGetItemId(phdr, offsetNumber);
if (ItemIdIsUsed(itemId) || ItemIdHasStorage(itemId))
{
elog(WARNING, "will not overwrite a used ItemId");
return InvalidOffsetNumber;
}
}
}
else
{
if (offsetNumber < limit)
needshuffle = true; /* need to move existing linp's */
}
}
else
{
/* offsetNumber was not passed in, so find a free slot */
/* if no free slot, we'll put it at limit (1st open slot) */
if (PageHasFreeLinePointers(phdr))
{
/*
* Look for "recyclable" (unused) ItemId. We check for no storage
* as well, just to be paranoid --- unused items should never have
* storage.
*/
for (offsetNumber = 1; offsetNumber < limit; offsetNumber++)
{
itemId = PageGetItemId(phdr, offsetNumber);
if (!ItemIdIsUsed(itemId) && !ItemIdHasStorage(itemId))
break;
}
if (offsetNumber >= limit)
{
/* the hint is wrong, so reset it */
PageClearHasFreeLinePointers(phdr);
}
}
else
{
/* don't bother searching if hint says there's no free slot */
offsetNumber = limit;
}
}
if (offsetNumber > limit)
{
elog(WARNING, "specified item offset is too large");
return InvalidOffsetNumber;
}
if (is_heap && offsetNumber > MaxHeapTuplesPerPage)
{
elog(WARNING, "can't put more than MaxHeapTuplesPerPage items in a heap page");
return InvalidOffsetNumber;
}
/*
* Compute new lower and upper pointers for page, see if it'll fit.
*
* Note: do arithmetic as signed ints, to avoid mistakes if, say,
* alignedSize > pd_upper.
*/
if (offsetNumber == limit || needshuffle)
lower = phdr->pd_lower + sizeof(ItemIdData);
else
lower = phdr->pd_lower;
alignedSize = MAXALIGN(size);
upper = (int) phdr->pd_upper - (int) alignedSize;
if (lower > upper)
return InvalidOffsetNumber;
/*
* OK to insert the item. First, shuffle the existing pointers if needed.
*/
itemId = PageGetItemId(phdr, offsetNumber);
if (needshuffle)
memmove(itemId + 1, itemId,
(limit - offsetNumber) * sizeof(ItemIdData));
/* set the item pointer */
ItemIdSetNormal(itemId, upper, size);
/* copy the item's data onto the page */
memcpy((char *) page + upper, item, size);
/* adjust page header */
phdr->pd_lower = (LocationIndex) lower;
phdr->pd_upper = (LocationIndex) upper;
return offsetNumber;
}
/*
* PageRepairFragmentation
*
* Frees fragmented space on a page.
* It doesn't remove unused line pointers! Please don't change this.
*
* This routine is usable for heap pages only, but see PageIndexMultiDelete.
*
* As a side effect, the page's PD_HAS_FREE_LINES hint bit is updated.
*/
void
PageRepairFragmentation(Page page)
{
Offset pd_lower = ((PageHeader) page)->pd_lower;
Offset pd_upper = ((PageHeader) page)->pd_upper;
Offset pd_special = ((PageHeader) page)->pd_special;
itemIdSort itemidbase,
itemidptr;
ItemId lp;
int nline,
nstorage,
nunused;
int i;
Size totallen;
Offset upper;
/*
* It's worth the trouble to be more paranoid here than in most places,
* because we are about to reshuffle data in (what is usually) a shared
* disk buffer. If we aren't careful then corrupted pointers, lengths,
* etc could cause us to clobber adjacent disk buffers, spreading the data
* loss further. So, check everything.
*/
if (pd_lower < SizeOfPageHeaderData ||
pd_lower > pd_upper ||
pd_upper > pd_special ||
pd_special > BLCKSZ ||
pd_special != MAXALIGN(pd_special))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("corrupted page pointers: lower = %u, upper = %u, special = %u",
pd_lower, pd_upper, pd_special)));
nline = PageGetMaxOffsetNumber(page);
nunused = nstorage = 0;
for (i = FirstOffsetNumber; i <= nline; i++)
{
lp = PageGetItemId(page, i);
if (ItemIdIsUsed(lp))
{
if (ItemIdHasStorage(lp))
nstorage++;
}
else
{
/* Unused entries should have lp_len = 0, but make sure */
ItemIdSetUnused(lp);
nunused++;
}
}
if (nstorage == 0)
{
/* Page is completely empty, so just reset it quickly */
((PageHeader) page)->pd_upper = pd_special;
}
else
{ /* nstorage != 0 */
/* Need to compact the page the hard way */
itemidbase = (itemIdSort) palloc(sizeof(itemIdSortData) * nstorage);
itemidptr = itemidbase;
totallen = 0;
for (i = 0; i < nline; i++)
{
lp = PageGetItemId(page, i + 1);
if (ItemIdHasStorage(lp))
{
itemidptr->offsetindex = i;
itemidptr->itemoff = ItemIdGetOffset(lp);
if (itemidptr->itemoff < (int) pd_upper ||
itemidptr->itemoff >= (int) pd_special)
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("corrupted item pointer: %u",
itemidptr->itemoff)));
itemidptr->alignedlen = MAXALIGN(ItemIdGetLength(lp));
totallen += itemidptr->alignedlen;
itemidptr++;
}
}
if (totallen > (Size) (pd_special - pd_lower))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("corrupted item lengths: total %u, available space %u",
(unsigned int) totallen, pd_special - pd_lower)));
/* sort itemIdSortData array into decreasing itemoff order */
qsort((char *) itemidbase, nstorage, sizeof(itemIdSortData),
itemoffcompare);
/* compactify page */
upper = pd_special;
for (i = 0, itemidptr = itemidbase; i < nstorage; i++, itemidptr++)
{
lp = PageGetItemId(page, itemidptr->offsetindex + 1);
upper -= itemidptr->alignedlen;
memmove((char *) page + upper,
(char *) page + itemidptr->itemoff,
itemidptr->alignedlen);
lp->lp_off = upper;
}
((PageHeader) page)->pd_upper = upper;
pfree(itemidbase);
}
/* Set hint bit for PageAddItem */
if (nunused > 0)
PageSetHasFreeLinePointers(page);
else
PageClearHasFreeLinePointers(page);
}
/*
* _hash_finish_split() -- Finish the previously interrupted split operation
*
* To complete the split operation, we form the hash table of TIDs in new
* bucket which is then used by split operation to skip tuples that are
* already moved before the split operation was previously interrupted.
*
* The caller must hold a pin, but no lock, on the metapage and old bucket's
* primary page buffer. The buffers are returned in the same state. (The
* metapage is only touched if it becomes necessary to add or remove overflow
* pages.)
*/
void
_hash_finish_split(Relation rel, Buffer metabuf, Buffer obuf, Bucket obucket,
uint32 maxbucket, uint32 highmask, uint32 lowmask)
{
HASHCTL hash_ctl;
HTAB *tidhtab;
Buffer bucket_nbuf = InvalidBuffer;
Buffer nbuf;
Page npage;
BlockNumber nblkno;
BlockNumber bucket_nblkno;
HashPageOpaque npageopaque;
Bucket nbucket;
bool found;
/* Initialize hash tables used to track TIDs */
memset(&hash_ctl, 0, sizeof(hash_ctl));
hash_ctl.keysize = sizeof(ItemPointerData);
hash_ctl.entrysize = sizeof(ItemPointerData);
hash_ctl.hcxt = CurrentMemoryContext;
tidhtab =
hash_create("bucket ctids",
256, /* arbitrary initial size */
&hash_ctl,
HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
bucket_nblkno = nblkno = _hash_get_newblock_from_oldbucket(rel, obucket);
/*
* Scan the new bucket and build hash table of TIDs
*/
for (;;)
{
OffsetNumber noffnum;
OffsetNumber nmaxoffnum;
nbuf = _hash_getbuf(rel, nblkno, HASH_READ,
LH_BUCKET_PAGE | LH_OVERFLOW_PAGE);
/* remember the primary bucket buffer to acquire cleanup lock on it. */
if (nblkno == bucket_nblkno)
bucket_nbuf = nbuf;
npage = BufferGetPage(nbuf);
npageopaque = (HashPageOpaque) PageGetSpecialPointer(npage);
/* Scan each tuple in new page */
nmaxoffnum = PageGetMaxOffsetNumber(npage);
for (noffnum = FirstOffsetNumber;
noffnum <= nmaxoffnum;
noffnum = OffsetNumberNext(noffnum))
{
IndexTuple itup;
/* Fetch the item's TID and insert it in hash table. */
itup = (IndexTuple) PageGetItem(npage,
PageGetItemId(npage, noffnum));
(void) hash_search(tidhtab, &itup->t_tid, HASH_ENTER, &found);
Assert(!found);
}
nblkno = npageopaque->hasho_nextblkno;
/*
* release our write lock without modifying buffer and ensure to
* retain the pin on primary bucket.
*/
if (nbuf == bucket_nbuf)
LockBuffer(nbuf, BUFFER_LOCK_UNLOCK);
else
_hash_relbuf(rel, nbuf);
/* Exit loop if no more overflow pages in new bucket */
if (!BlockNumberIsValid(nblkno))
break;
}
/*
* Conditionally get the cleanup lock on old and new buckets to perform
* the split operation. If we don't get the cleanup locks, silently give
* up and next insertion on old bucket will try again to complete the
* split.
*/
if (!ConditionalLockBufferForCleanup(obuf))
{
hash_destroy(tidhtab);
return;
}
if (!ConditionalLockBufferForCleanup(bucket_nbuf))
{
LockBuffer(obuf, BUFFER_LOCK_UNLOCK);
hash_destroy(tidhtab);
return;
}
npage = BufferGetPage(bucket_nbuf);
npageopaque = (HashPageOpaque) PageGetSpecialPointer(npage);
nbucket = npageopaque->hasho_bucket;
_hash_splitbucket(rel, metabuf, obucket,
nbucket, obuf, bucket_nbuf, tidhtab,
maxbucket, highmask, lowmask);
_hash_dropbuf(rel, bucket_nbuf);
hash_destroy(tidhtab);
}
/* ----------------------------------------------------------------
* BitmapHeapNext
*
* Retrieve next tuple from the BitmapHeapScan node's currentRelation
* ----------------------------------------------------------------
*/
static TupleTableSlot *
BitmapHeapNext(BitmapHeapScanState *node)
{
ExprContext *econtext;
HeapScanDesc scan;
TIDBitmap *tbm;
TBMIterator *tbmiterator;
TBMIterateResult *tbmres;
#ifdef USE_PREFETCH
TBMIterator *prefetch_iterator;
#endif
OffsetNumber targoffset;
TupleTableSlot *slot;
/*
* extract necessary information from index scan node
*/
econtext = node->ss.ps.ps_ExprContext;
slot = node->ss.ss_ScanTupleSlot;
scan = node->ss.ss_currentScanDesc;
tbm = node->tbm;
tbmiterator = node->tbmiterator;
tbmres = node->tbmres;
#ifdef USE_PREFETCH
prefetch_iterator = node->prefetch_iterator;
#endif
/*
* If we haven't yet performed the underlying index scan, do it, and begin
* the iteration over the bitmap.
*
* For prefetching, we use *two* iterators, one for the pages we are
* actually scanning and another that runs ahead of the first for
* prefetching. node->prefetch_pages tracks exactly how many pages ahead
* the prefetch iterator is. Also, node->prefetch_target tracks the
* desired prefetch distance, which starts small and increases up to the
* GUC-controlled maximum, target_prefetch_pages. This is to avoid doing
* a lot of prefetching in a scan that stops after a few tuples because of
* a LIMIT.
*/
if (tbm == NULL)
{
tbm = (TIDBitmap *) MultiExecProcNode(outerPlanState(node));
if (!tbm || !IsA(tbm, TIDBitmap))
elog(ERROR, "unrecognized result from subplan");
node->tbm = tbm;
node->tbmiterator = tbmiterator = tbm_begin_iterate(tbm);
node->tbmres = tbmres = NULL;
#ifdef USE_PREFETCH
if (target_prefetch_pages > 0)
{
node->prefetch_iterator = prefetch_iterator = tbm_begin_iterate(tbm);
node->prefetch_pages = 0;
node->prefetch_target = -1;
}
#endif /* USE_PREFETCH */
}
for (;;)
{
Page dp;
ItemId lp;
/*
* Get next page of results if needed
*/
if (tbmres == NULL)
{
node->tbmres = tbmres = tbm_iterate(tbmiterator);
if (tbmres == NULL)
{
/* no more entries in the bitmap */
break;
}
#ifdef USE_PREFETCH
if (node->prefetch_pages > 0)
{
/* The main iterator has closed the distance by one page */
node->prefetch_pages--;
}
else if (prefetch_iterator)
{
/* Do not let the prefetch iterator get behind the main one */
TBMIterateResult *tbmpre = tbm_iterate(prefetch_iterator);
if (tbmpre == NULL || tbmpre->blockno != tbmres->blockno)
elog(ERROR, "prefetch and main iterators are out of sync");
}
#endif /* USE_PREFETCH */
/*
* Ignore any claimed entries past what we think is the end of the
* relation. (This is probably not necessary given that we got at
* least AccessShareLock on the table before performing any of the
* indexscans, but let's be safe.)
*/
if (tbmres->blockno >= scan->rs_nblocks)
{
node->tbmres = tbmres = NULL;
continue;
}
/*
* Fetch the current heap page and identify candidate tuples.
*/
bitgetpage(scan, tbmres);
/*
* Set rs_cindex to first slot to examine
*/
scan->rs_cindex = 0;
#ifdef USE_PREFETCH
/*
* Increase prefetch target if it's not yet at the max. Note that
* we will increase it to zero after fetching the very first
* page/tuple, then to one after the second tuple is fetched, then
* it doubles as later pages are fetched.
*/
if (node->prefetch_target >= target_prefetch_pages)
/* don't increase any further */ ;
else if (node->prefetch_target >= target_prefetch_pages / 2)
node->prefetch_target = target_prefetch_pages;
else if (node->prefetch_target > 0)
node->prefetch_target *= 2;
else
node->prefetch_target++;
#endif /* USE_PREFETCH */
}
else
{
/*
* Continuing in previously obtained page; advance rs_cindex
*/
scan->rs_cindex++;
#ifdef USE_PREFETCH
/*
* Try to prefetch at least a few pages even before we get to the
* second page if we don't stop reading after the first tuple.
*/
if (node->prefetch_target < target_prefetch_pages)
node->prefetch_target++;
#endif /* USE_PREFETCH */
}
/*
* Out of range? If so, nothing more to look at on this page
*/
if (scan->rs_cindex < 0 || scan->rs_cindex >= scan->rs_ntuples)
{
node->tbmres = tbmres = NULL;
continue;
}
#ifdef USE_PREFETCH
/*
* We issue prefetch requests *after* fetching the current page to try
* to avoid having prefetching interfere with the main I/O. Also, this
* should happen only when we have determined there is still something
* to do on the current page, else we may uselessly prefetch the same
* page we are just about to request for real.
*/
if (prefetch_iterator)
{
while (node->prefetch_pages < node->prefetch_target)
{
TBMIterateResult *tbmpre = tbm_iterate(prefetch_iterator);
if (tbmpre == NULL)
{
/* No more pages to prefetch */
tbm_end_iterate(prefetch_iterator);
node->prefetch_iterator = prefetch_iterator = NULL;
break;
}
node->prefetch_pages++;
PrefetchBuffer(scan->rs_rd, MAIN_FORKNUM, tbmpre->blockno);
}
}
#endif /* USE_PREFETCH */
/*
* Okay to fetch the tuple
*/
targoffset = scan->rs_vistuples[scan->rs_cindex];
dp = (Page) BufferGetPage(scan->rs_cbuf);
lp = PageGetItemId(dp, targoffset);
Assert(ItemIdIsNormal(lp));
scan->rs_ctup.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
scan->rs_ctup.t_len = ItemIdGetLength(lp);
ItemPointerSet(&scan->rs_ctup.t_self, tbmres->blockno, targoffset);
pgstat_count_heap_fetch(scan->rs_rd);
/*
* Set up the result slot to point to this tuple. Note that the slot
* acquires a pin on the buffer.
*/
ExecStoreTuple(&scan->rs_ctup,
slot,
scan->rs_cbuf,
false);
/*
* If we are using lossy info, we have to recheck the qual conditions
* at every tuple.
*/
if (tbmres->recheck)
{
econtext->ecxt_scantuple = slot;
ResetExprContext(econtext);
if (!ExecQual(node->bitmapqualorig, econtext, false))
{
/* Fails recheck, so drop it and loop back for another */
InstrCountFiltered2(node, 1);
ExecClearTuple(slot);
continue;
}
}
/* OK to return this tuple */
return slot;
}
/*
* if we get here it means we are at the end of the scan..
*/
return ExecClearTuple(slot);
}
/*
* _hash_splitbucket -- split 'obucket' into 'obucket' and 'nbucket'
*
* This routine is used to partition the tuples between old and new bucket and
* is used to finish the incomplete split operations. To finish the previously
* interrupted split operation, the caller needs to fill htab. If htab is set,
* then we skip the movement of tuples that exists in htab, otherwise NULL
* value of htab indicates movement of all the tuples that belong to the new
* bucket.
*
* We are splitting a bucket that consists of a base bucket page and zero
* or more overflow (bucket chain) pages. We must relocate tuples that
* belong in the new bucket.
*
* The caller must hold cleanup locks on both buckets to ensure that
* no one else is trying to access them (see README).
*
* The caller must hold a pin, but no lock, on the metapage buffer.
* The buffer is returned in the same state. (The metapage is only
* touched if it becomes necessary to add or remove overflow pages.)
*
* Split needs to retain pin on primary bucket pages of both old and new
* buckets till end of operation. This is to prevent vacuum from starting
* while a split is in progress.
*
* In addition, the caller must have created the new bucket's base page,
* which is passed in buffer nbuf, pinned and write-locked. The lock will be
* released here and pin must be released by the caller. (The API is set up
* this way because we must do _hash_getnewbuf() before releasing the metapage
* write lock. So instead of passing the new bucket's start block number, we
* pass an actual buffer.)
*/
static void
_hash_splitbucket(Relation rel,
Buffer metabuf,
Bucket obucket,
Bucket nbucket,
Buffer obuf,
Buffer nbuf,
HTAB *htab,
uint32 maxbucket,
uint32 highmask,
uint32 lowmask)
{
Buffer bucket_obuf;
Buffer bucket_nbuf;
Page opage;
Page npage;
HashPageOpaque oopaque;
HashPageOpaque nopaque;
OffsetNumber itup_offsets[MaxIndexTuplesPerPage];
IndexTuple itups[MaxIndexTuplesPerPage];
Size all_tups_size = 0;
int i;
uint16 nitups = 0;
bucket_obuf = obuf;
opage = BufferGetPage(obuf);
oopaque = (HashPageOpaque) PageGetSpecialPointer(opage);
bucket_nbuf = nbuf;
npage = BufferGetPage(nbuf);
nopaque = (HashPageOpaque) PageGetSpecialPointer(npage);
/*
* Partition the tuples in the old bucket between the old bucket and the
* new bucket, advancing along the old bucket's overflow bucket chain and
* adding overflow pages to the new bucket as needed. Outer loop iterates
* once per page in old bucket.
*/
for (;;)
{
BlockNumber oblkno;
OffsetNumber ooffnum;
OffsetNumber omaxoffnum;
/* Scan each tuple in old page */
omaxoffnum = PageGetMaxOffsetNumber(opage);
for (ooffnum = FirstOffsetNumber;
ooffnum <= omaxoffnum;
ooffnum = OffsetNumberNext(ooffnum))
{
IndexTuple itup;
Size itemsz;
Bucket bucket;
bool found = false;
/* skip dead tuples */
if (ItemIdIsDead(PageGetItemId(opage, ooffnum)))
continue;
/*
* Before inserting a tuple, probe the hash table containing TIDs
* of tuples belonging to new bucket, if we find a match, then
* skip that tuple, else fetch the item's hash key (conveniently
* stored in the item) and determine which bucket it now belongs
* in.
*/
itup = (IndexTuple) PageGetItem(opage,
PageGetItemId(opage, ooffnum));
if (htab)
(void) hash_search(htab, &itup->t_tid, HASH_FIND, &found);
if (found)
continue;
bucket = _hash_hashkey2bucket(_hash_get_indextuple_hashkey(itup),
maxbucket, highmask, lowmask);
if (bucket == nbucket)
{
IndexTuple new_itup;
/*
* make a copy of index tuple as we have to scribble on it.
*/
new_itup = CopyIndexTuple(itup);
/*
* mark the index tuple as moved by split, such tuples are
* skipped by scan if there is split in progress for a bucket.
*/
new_itup->t_info |= INDEX_MOVED_BY_SPLIT_MASK;
/*
* insert the tuple into the new bucket. if it doesn't fit on
* the current page in the new bucket, we must allocate a new
* overflow page and place the tuple on that page instead.
*/
itemsz = IndexTupleDSize(*new_itup);
itemsz = MAXALIGN(itemsz);
if (PageGetFreeSpaceForMultipleTuples(npage, nitups + 1) < (all_tups_size + itemsz))
{
/*
* Change the shared buffer state in critical section,
* otherwise any error could make it unrecoverable.
*/
START_CRIT_SECTION();
_hash_pgaddmultitup(rel, nbuf, itups, itup_offsets, nitups);
MarkBufferDirty(nbuf);
/* log the split operation before releasing the lock */
log_split_page(rel, nbuf);
END_CRIT_SECTION();
/* drop lock, but keep pin */
LockBuffer(nbuf, BUFFER_LOCK_UNLOCK);
/* be tidy */
for (i = 0; i < nitups; i++)
pfree(itups[i]);
nitups = 0;
all_tups_size = 0;
/* chain to a new overflow page */
nbuf = _hash_addovflpage(rel, metabuf, nbuf, (nbuf == bucket_nbuf) ? true : false);
npage = BufferGetPage(nbuf);
nopaque = (HashPageOpaque) PageGetSpecialPointer(npage);
}
itups[nitups++] = new_itup;
all_tups_size += itemsz;
}
else
{
/*
* the tuple stays on this page, so nothing to do.
*/
Assert(bucket == obucket);
}
}
oblkno = oopaque->hasho_nextblkno;
/* retain the pin on the old primary bucket */
if (obuf == bucket_obuf)
LockBuffer(obuf, BUFFER_LOCK_UNLOCK);
else
_hash_relbuf(rel, obuf);
/* Exit loop if no more overflow pages in old bucket */
if (!BlockNumberIsValid(oblkno))
{
/*
* Change the shared buffer state in critical section, otherwise
* any error could make it unrecoverable.
*/
START_CRIT_SECTION();
_hash_pgaddmultitup(rel, nbuf, itups, itup_offsets, nitups);
MarkBufferDirty(nbuf);
/* log the split operation before releasing the lock */
log_split_page(rel, nbuf);
END_CRIT_SECTION();
if (nbuf == bucket_nbuf)
LockBuffer(nbuf, BUFFER_LOCK_UNLOCK);
else
_hash_relbuf(rel, nbuf);
/* be tidy */
for (i = 0; i < nitups; i++)
pfree(itups[i]);
break;
}
/* Else, advance to next old page */
obuf = _hash_getbuf(rel, oblkno, HASH_READ, LH_OVERFLOW_PAGE);
opage = BufferGetPage(obuf);
oopaque = (HashPageOpaque) PageGetSpecialPointer(opage);
}
/*
* We're at the end of the old bucket chain, so we're done partitioning
* the tuples. Mark the old and new buckets to indicate split is
* finished.
*
* To avoid deadlocks due to locking order of buckets, first lock the old
* bucket and then the new bucket.
*/
LockBuffer(bucket_obuf, BUFFER_LOCK_EXCLUSIVE);
opage = BufferGetPage(bucket_obuf);
oopaque = (HashPageOpaque) PageGetSpecialPointer(opage);
LockBuffer(bucket_nbuf, BUFFER_LOCK_EXCLUSIVE);
npage = BufferGetPage(bucket_nbuf);
nopaque = (HashPageOpaque) PageGetSpecialPointer(npage);
START_CRIT_SECTION();
oopaque->hasho_flag &= ~LH_BUCKET_BEING_SPLIT;
nopaque->hasho_flag &= ~LH_BUCKET_BEING_POPULATED;
/*
* After the split is finished, mark the old bucket to indicate that it
* contains deletable tuples. We will clear split-cleanup flag after
* deleting such tuples either at the end of split or at the next split
* from old bucket or at the time of vacuum.
*/
oopaque->hasho_flag |= LH_BUCKET_NEEDS_SPLIT_CLEANUP;
/*
* now write the buffers, here we don't release the locks as caller is
* responsible to release locks.
*/
MarkBufferDirty(bucket_obuf);
MarkBufferDirty(bucket_nbuf);
if (RelationNeedsWAL(rel))
{
XLogRecPtr recptr;
xl_hash_split_complete xlrec;
xlrec.old_bucket_flag = oopaque->hasho_flag;
xlrec.new_bucket_flag = nopaque->hasho_flag;
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfHashSplitComplete);
XLogRegisterBuffer(0, bucket_obuf, REGBUF_STANDARD);
XLogRegisterBuffer(1, bucket_nbuf, REGBUF_STANDARD);
recptr = XLogInsert(RM_HASH_ID, XLOG_HASH_SPLIT_COMPLETE);
PageSetLSN(BufferGetPage(bucket_obuf), recptr);
PageSetLSN(BufferGetPage(bucket_nbuf), recptr);
}
END_CRIT_SECTION();
/*
* If possible, clean up the old bucket. We might not be able to do this
* if someone else has a pin on it, but if not then we can go ahead. This
* isn't absolutely necessary, but it reduces bloat; if we don't do it
* now, VACUUM will do it eventually, but maybe not until new overflow
* pages have been allocated. Note that there's no need to clean up the
* new bucket.
*/
if (IsBufferCleanupOK(bucket_obuf))
{
LockBuffer(bucket_nbuf, BUFFER_LOCK_UNLOCK);
hashbucketcleanup(rel, obucket, bucket_obuf,
BufferGetBlockNumber(bucket_obuf), NULL,
maxbucket, highmask, lowmask, NULL, NULL, true,
NULL, NULL);
}
else
{
LockBuffer(bucket_nbuf, BUFFER_LOCK_UNLOCK);
LockBuffer(bucket_obuf, BUFFER_LOCK_UNLOCK);
}
}
/*
* For all items in this page, find their respective root line pointers.
* If item k is part of a HOT-chain with root at item j, then we set
* root_offsets[k - 1] = j.
*
* The passed-in root_offsets array must have MaxHeapTuplesPerPage entries.
* We zero out all unused entries.
*
* The function must be called with at least share lock on the buffer, to
* prevent concurrent prune operations.
*
* Note: The information collected here is valid only as long as the caller
* holds a pin on the buffer. Once pin is released, a tuple might be pruned
* and reused by a completely unrelated tuple.
*/
void
heap_get_root_tuples(Page page, OffsetNumber *root_offsets)
{
OffsetNumber offnum,
maxoff;
MemSet(root_offsets, 0, MaxHeapTuplesPerPage * sizeof(OffsetNumber));
maxoff = PageGetMaxOffsetNumber(page);
for (offnum = FirstOffsetNumber; offnum <= maxoff; offnum = OffsetNumberNext(offnum))
{
ItemId lp = PageGetItemId(page, offnum);
HeapTupleHeader htup;
OffsetNumber nextoffnum;
TransactionId priorXmax;
/* skip unused and dead items */
if (!ItemIdIsUsed(lp) || ItemIdIsDead(lp))
continue;
if (ItemIdIsNormal(lp))
{
htup = (HeapTupleHeader) PageGetItem(page, lp);
/*
* Check if this tuple is part of a HOT-chain rooted at some other
* tuple. If so, skip it for now; we'll process it when we find
* its root.
*/
if (HeapTupleHeaderIsHeapOnly(htup))
continue;
/*
* This is either a plain tuple or the root of a HOT-chain.
* Remember it in the mapping.
*/
root_offsets[offnum - 1] = offnum;
/* If it's not the start of a HOT-chain, we're done with it */
if (!HeapTupleHeaderIsHotUpdated(htup))
continue;
/* Set up to scan the HOT-chain */
nextoffnum = ItemPointerGetOffsetNumber(&htup->t_ctid);
priorXmax = HeapTupleHeaderGetXmax(htup);
}
else
{
/* Must be a redirect item. We do not set its root_offsets entry */
Assert(ItemIdIsRedirected(lp));
/* Set up to scan the HOT-chain */
nextoffnum = ItemIdGetRedirect(lp);
priorXmax = InvalidTransactionId;
}
/*
* Now follow the HOT-chain and collect other tuples in the chain.
*
* Note: Even though this is a nested loop, the complexity of the
* function is O(N) because a tuple in the page should be visited not
* more than twice, once in the outer loop and once in HOT-chain
* chases.
*/
for (;;)
{
lp = PageGetItemId(page, nextoffnum);
/* Check for broken chains */
if (!ItemIdIsNormal(lp))
break;
htup = (HeapTupleHeader) PageGetItem(page, lp);
if (TransactionIdIsValid(priorXmax) &&
!TransactionIdEquals(priorXmax, HeapTupleHeaderGetXmin(htup)))
break;
/* Remember the root line pointer for this item */
root_offsets[nextoffnum - 1] = offnum;
/* Advance to next chain member, if any */
if (!HeapTupleHeaderIsHotUpdated(htup))
break;
nextoffnum = ItemPointerGetOffsetNumber(&htup->t_ctid);
priorXmax = HeapTupleHeaderGetXmax(htup);
}
}
}
/*
* Prune specified item pointer or a HOT chain originating at that item.
*
* If the item is an index-referenced tuple (i.e. not a heap-only tuple),
* the HOT chain is pruned by removing all DEAD tuples at the start of the HOT
* chain. We also prune any RECENTLY_DEAD tuples preceding a DEAD tuple.
* This is OK because a RECENTLY_DEAD tuple preceding a DEAD tuple is really
* DEAD, the OldestXmin test is just too coarse to detect it.
*
* The root line pointer is redirected to the tuple immediately after the
* latest DEAD tuple. If all tuples in the chain are DEAD, the root line
* pointer is marked LP_DEAD. (This includes the case of a DEAD simple
* tuple, which we treat as a chain of length 1.)
*
* OldestXmin is the cutoff XID used to identify dead tuples.
*
* We don't actually change the page here, except perhaps for hint-bit updates
* caused by HeapTupleSatisfiesVacuum. We just add entries to the arrays in
* prstate showing the changes to be made. Items to be redirected are added
* to the redirected[] array (two entries per redirection); items to be set to
* LP_DEAD state are added to nowdead[]; and items to be set to LP_UNUSED
* state are added to nowunused[].
*
* Returns the number of tuples (to be) deleted from the page.
*/
static int
heap_prune_chain(Relation relation, Buffer buffer, OffsetNumber rootoffnum,
TransactionId OldestXmin,
PruneState *prstate)
{
int ndeleted = 0;
Page dp = (Page) BufferGetPage(buffer);
TransactionId priorXmax = InvalidTransactionId;
ItemId rootlp;
HeapTupleHeader htup;
OffsetNumber latestdead = InvalidOffsetNumber,
maxoff = PageGetMaxOffsetNumber(dp),
offnum;
OffsetNumber chainitems[MaxHeapTuplesPerPage];
int nchain = 0,
i;
rootlp = PageGetItemId(dp, rootoffnum);
/*
* If it's a heap-only tuple, then it is not the start of a HOT chain.
*/
if (ItemIdIsNormal(rootlp))
{
htup = (HeapTupleHeader) PageGetItem(dp, rootlp);
if (HeapTupleHeaderIsHeapOnly(htup))
{
/*
* If the tuple is DEAD and doesn't chain to anything else, mark
* it unused immediately. (If it does chain, we can only remove
* it as part of pruning its chain.)
*
* We need this primarily to handle aborted HOT updates, that is,
* XMIN_INVALID heap-only tuples. Those might not be linked to by
* any chain, since the parent tuple might be re-updated before
* any pruning occurs. So we have to be able to reap them
* separately from chain-pruning. (Note that
* HeapTupleHeaderIsHotUpdated will never return true for an
* XMIN_INVALID tuple, so this code will work even when there were
* sequential updates within the aborted transaction.)
*
* Note that we might first arrive at a dead heap-only tuple
* either here or while following a chain below. Whichever path
* gets there first will mark the tuple unused.
*/
if (HeapTupleSatisfiesVacuum(htup, OldestXmin, buffer)
== HEAPTUPLE_DEAD && !HeapTupleHeaderIsHotUpdated(htup))
{
heap_prune_record_unused(prstate, rootoffnum);
HeapTupleHeaderAdvanceLatestRemovedXid(htup,
&prstate->latestRemovedXid);
ndeleted++;
}
/* Nothing more to do */
return ndeleted;
}
}
/* Start from the root tuple */
offnum = rootoffnum;
/* while not end of the chain */
for (;;)
{
ItemId lp;
bool tupdead,
recent_dead;
/* Some sanity checks */
if (offnum < FirstOffsetNumber || offnum > maxoff)
break;
/* If item is already processed, stop --- it must not be same chain */
if (prstate->marked[offnum])
break;
lp = PageGetItemId(dp, offnum);
/* Unused item obviously isn't part of the chain */
if (!ItemIdIsUsed(lp))
break;
/*
* If we are looking at the redirected root line pointer, jump to the
* first normal tuple in the chain. If we find a redirect somewhere
* else, stop --- it must not be same chain.
*/
if (ItemIdIsRedirected(lp))
{
if (nchain > 0)
break; /* not at start of chain */
chainitems[nchain++] = offnum;
offnum = ItemIdGetRedirect(rootlp);
continue;
}
/*
* Likewise, a dead item pointer can't be part of the chain. (We
* already eliminated the case of dead root tuple outside this
* function.)
*/
if (ItemIdIsDead(lp))
break;
Assert(ItemIdIsNormal(lp));
htup = (HeapTupleHeader) PageGetItem(dp, lp);
/*
* Check the tuple XMIN against prior XMAX, if any
*/
if (TransactionIdIsValid(priorXmax) &&
!TransactionIdEquals(HeapTupleHeaderGetXmin(htup), priorXmax))
break;
/*
* OK, this tuple is indeed a member of the chain.
*/
chainitems[nchain++] = offnum;
/*
* Check tuple's visibility status.
*/
tupdead = recent_dead = false;
switch (HeapTupleSatisfiesVacuum(htup, OldestXmin, buffer))
{
case HEAPTUPLE_DEAD:
tupdead = true;
break;
case HEAPTUPLE_RECENTLY_DEAD:
recent_dead = true;
/*
* This tuple may soon become DEAD. Update the hint field so
* that the page is reconsidered for pruning in future.
*/
heap_prune_record_prunable(prstate,
HeapTupleHeaderGetXmax(htup));
break;
case HEAPTUPLE_DELETE_IN_PROGRESS:
/*
* This tuple may soon become DEAD. Update the hint field so
* that the page is reconsidered for pruning in future.
*/
heap_prune_record_prunable(prstate,
HeapTupleHeaderGetXmax(htup));
break;
case HEAPTUPLE_LIVE:
case HEAPTUPLE_INSERT_IN_PROGRESS:
/*
* If we wanted to optimize for aborts, we might consider
* marking the page prunable when we see INSERT_IN_PROGRESS.
* But we don't. See related decisions about when to mark the
* page prunable in heapam.c.
*/
break;
default:
elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result");
break;
}
/*
* Remember the last DEAD tuple seen. We will advance past
* RECENTLY_DEAD tuples just in case there's a DEAD one after them;
* but we can't advance past anything else. (XXX is it really worth
* continuing to scan beyond RECENTLY_DEAD? The case where we will
* find another DEAD tuple is a fairly unusual corner case.)
*/
if (tupdead)
{
latestdead = offnum;
HeapTupleHeaderAdvanceLatestRemovedXid(htup,
&prstate->latestRemovedXid);
}
else if (!recent_dead)
break;
/*
* If the tuple is not HOT-updated, then we are at the end of this
* HOT-update chain.
*/
if (!HeapTupleHeaderIsHotUpdated(htup))
break;
/*
* Advance to next chain member.
*/
Assert(ItemPointerGetBlockNumber(&htup->t_ctid) ==
BufferGetBlockNumber(buffer));
offnum = ItemPointerGetOffsetNumber(&htup->t_ctid);
priorXmax = HeapTupleHeaderGetXmax(htup);
}
/*
* If we found a DEAD tuple in the chain, adjust the HOT chain so that all
* the DEAD tuples at the start of the chain are removed and the root line
* pointer is appropriately redirected.
*/
if (OffsetNumberIsValid(latestdead))
{
/*
* Mark as unused each intermediate item that we are able to remove
* from the chain.
*
* When the previous item is the last dead tuple seen, we are at the
* right candidate for redirection.
*/
for (i = 1; (i < nchain) && (chainitems[i - 1] != latestdead); i++)
{
heap_prune_record_unused(prstate, chainitems[i]);
ndeleted++;
}
/*
* If the root entry had been a normal tuple, we are deleting it, so
* count it in the result. But changing a redirect (even to DEAD
* state) doesn't count.
*/
if (ItemIdIsNormal(rootlp))
ndeleted++;
/*
* If the DEAD tuple is at the end of the chain, the entire chain is
* dead and the root line pointer can be marked dead. Otherwise just
* redirect the root to the correct chain member.
*/
if (i >= nchain)
heap_prune_record_dead(prstate, rootoffnum);
else
heap_prune_record_redirect(prstate, rootoffnum, chainitems[i]);
}
else if (nchain < 2 && ItemIdIsRedirected(rootlp))
{
/*
* We found a redirect item that doesn't point to a valid follow-on
* item. This can happen if the loop in heap_page_prune caused us to
* visit the dead successor of a redirect item before visiting the
* redirect item. We can clean up by setting the redirect item to
* DEAD state.
*/
heap_prune_record_dead(prstate, rootoffnum);
}
return ndeleted;
}
/*
* Rescan end pages to verify that they are (still) empty of tuples.
*
* Returns number of nondeletable pages (last nonempty page + 1).
*/
static BlockNumber
count_nondeletable_pages(Relation onerel, LVRelStats *vacrelstats)
{
MIRROREDLOCK_BUFMGR_DECLARE;
BlockNumber blkno;
/* Strange coding of loop control is needed because blkno is unsigned */
blkno = vacrelstats->rel_pages;
while (blkno > vacrelstats->nonempty_pages)
{
Buffer buf;
Page page;
OffsetNumber offnum,
maxoff;
bool hastup;
/*
* We don't insert a vacuum delay point here, because we have an
* exclusive lock on the table which we want to hold for as short a
* time as possible. We still need to check for interrupts however.
*/
CHECK_FOR_INTERRUPTS();
blkno--;
/* -------- MirroredLock ---------- */
MIRROREDLOCK_BUFMGR_LOCK;
buf = ReadBufferWithStrategy(onerel, blkno, vac_strategy);
/* In this phase we only need shared access to the buffer */
LockBuffer(buf, BUFFER_LOCK_SHARE);
page = BufferGetPage(buf);
if (PageIsNew(page) || PageIsEmpty(page))
{
/* PageIsNew probably shouldn't happen... */
UnlockReleaseBuffer(buf);
MIRROREDLOCK_BUFMGR_UNLOCK;
/* -------- MirroredLock ---------- */
continue;
}
hastup = false;
maxoff = PageGetMaxOffsetNumber(page);
for (offnum = FirstOffsetNumber;
offnum <= maxoff;
offnum = OffsetNumberNext(offnum))
{
ItemId itemid;
itemid = PageGetItemId(page, offnum);
/*
* Note: any non-unused item should be taken as a reason to keep
* this page. We formerly thought that DEAD tuples could be
* thrown away, but that's not so, because we'd not have cleaned
* out their index entries.
*/
if (ItemIdIsUsed(itemid))
{
hastup = true;
break; /* can stop scanning */
}
} /* scan along page */
UnlockReleaseBuffer(buf);
MIRROREDLOCK_BUFMGR_UNLOCK;
/* -------- MirroredLock ---------- */
/* Done scanning if we found a tuple here */
if (hastup)
return blkno + 1;
}
/*
* If we fall out of the loop, all the previously-thought-to-be-empty
* pages still are; we need not bother to look at the last known-nonempty
* page.
*/
return vacrelstats->nonempty_pages;
}
/*
* PageIndexTupleDelete
*
* This routine does the work of removing a tuple from an index page.
*
* Unlike heap pages, we compact out the line pointer for the removed tuple.
*/
void
PageIndexTupleDelete(Page page, OffsetNumber offnum)
{
PageHeader phdr = (PageHeader) page;
char *addr;
ItemId tup;
Size size;
unsigned offset;
int nbytes;
int offidx;
int nline;
/*
* As with PageRepairFragmentation, paranoia seems justified.
*/
if (phdr->pd_lower < SizeOfPageHeaderData ||
phdr->pd_lower > phdr->pd_upper ||
phdr->pd_upper > phdr->pd_special ||
phdr->pd_special > BLCKSZ)
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("corrupted page pointers: lower = %u, upper = %u, special = %u",
phdr->pd_lower, phdr->pd_upper, phdr->pd_special)));
nline = PageGetMaxOffsetNumber(page);
if ((int) offnum <= 0 || (int) offnum > nline)
elog(ERROR, "invalid index offnum: %u", offnum);
/* change offset number to offset index */
offidx = offnum - 1;
tup = PageGetItemId(page, offnum);
Assert(ItemIdHasStorage(tup));
size = ItemIdGetLength(tup);
offset = ItemIdGetOffset(tup);
if (offset < phdr->pd_upper || (offset + size) > phdr->pd_special ||
offset != MAXALIGN(offset) || size != MAXALIGN(size))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("corrupted item pointer: offset = %u, size = %u",
offset, (unsigned int) size)));
/*
* First, we want to get rid of the pd_linp entry for the index tuple. We
* copy all subsequent linp's back one slot in the array. We don't use
* PageGetItemId, because we are manipulating the _array_, not individual
* linp's.
*/
nbytes = phdr->pd_lower -
((char *) &phdr->pd_linp[offidx + 1] - (char *) phdr);
if (nbytes > 0)
memmove((char *) &(phdr->pd_linp[offidx]),
(char *) &(phdr->pd_linp[offidx + 1]),
nbytes);
/*
* Now move everything between the old upper bound (beginning of tuple
* space) and the beginning of the deleted tuple forward, so that space in
* the middle of the page is left free. If we've just deleted the tuple
* at the beginning of tuple space, then there's no need to do the copy
* (and bcopy on some architectures SEGV's if asked to move zero bytes).
*/
/* beginning of tuple space */
addr = (char *) page + phdr->pd_upper;
if (offset > phdr->pd_upper)
memmove(addr + size, addr, (int) (offset - phdr->pd_upper));
/* adjust free space boundary pointers */
phdr->pd_upper += size;
phdr->pd_lower -= sizeof(ItemIdData);
/*
* Finally, we need to adjust the linp entries that remain.
*
* Anything that used to be before the deleted tuple's data was moved
* forward by the size of the deleted tuple.
*/
if (!PageIsEmpty(page))
{
int i;
nline--; /* there's one less than when we started */
for (i = 1; i <= nline; i++)
{
ItemId ii = PageGetItemId(phdr, i);
Assert(ItemIdHasStorage(ii));
if (ItemIdGetOffset(ii) <= offset)
ii->lp_off += size;
}
}
}
/*
* lazy_scan_heap() -- scan an open heap relation
*
* This routine sets commit status bits, builds lists of dead tuples
* and pages with free space, and calculates statistics on the number
* of live tuples in the heap. When done, or when we run low on space
* for dead-tuple TIDs, invoke vacuuming of indexes and heap.
*
* If there are no indexes then we just vacuum each dirty page as we
* process it, since there's no point in gathering many tuples.
*/
static void
lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats,
Relation *Irel, int nindexes, List *updated_stats, List *all_extra_oids)
{
MIRROREDLOCK_BUFMGR_DECLARE;
BlockNumber nblocks,
blkno;
HeapTupleData tuple;
char *relname;
BlockNumber empty_pages,
vacuumed_pages;
double num_tuples,
tups_vacuumed,
nkeep,
nunused;
IndexBulkDeleteResult **indstats;
int i;
int reindex_count = 1;
PGRUsage ru0;
/* Fetch gp_persistent_relation_node information that will be added to XLOG record. */
RelationFetchGpRelationNodeForXLog(onerel);
pg_rusage_init(&ru0);
relname = RelationGetRelationName(onerel);
ereport(elevel,
(errmsg("vacuuming \"%s.%s\"",
get_namespace_name(RelationGetNamespace(onerel)),
relname)));
empty_pages = vacuumed_pages = 0;
num_tuples = tups_vacuumed = nkeep = nunused = 0;
indstats = (IndexBulkDeleteResult **)
palloc0(nindexes * sizeof(IndexBulkDeleteResult *));
nblocks = RelationGetNumberOfBlocks(onerel);
vacrelstats->rel_pages = nblocks;
vacrelstats->nonempty_pages = 0;
lazy_space_alloc(vacrelstats, nblocks);
for (blkno = 0; blkno < nblocks; blkno++)
{
Buffer buf;
Page page;
OffsetNumber offnum,
maxoff;
bool tupgone,
hastup;
int prev_dead_count;
OffsetNumber frozen[MaxOffsetNumber];
int nfrozen;
vacuum_delay_point();
/*
* If we are close to overrunning the available space for dead-tuple
* TIDs, pause and do a cycle of vacuuming before we tackle this page.
*/
if ((vacrelstats->max_dead_tuples - vacrelstats->num_dead_tuples) < MaxHeapTuplesPerPage &&
vacrelstats->num_dead_tuples > 0)
{
/* Remove index entries */
for (i = 0; i < nindexes; i++)
{
List *extra_oids = get_oids_for_bitmap(all_extra_oids, Irel[i],
onerel, reindex_count);
lazy_vacuum_index(Irel[i],
&indstats[i],
vacrelstats,
extra_oids);
list_free(extra_oids);
}
reindex_count++;
/* Remove tuples from heap */
lazy_vacuum_heap(onerel, vacrelstats);
/* Forget the now-vacuumed tuples, and press on */
vacrelstats->num_dead_tuples = 0;
vacrelstats->num_index_scans++;
}
/* -------- MirroredLock ---------- */
MIRROREDLOCK_BUFMGR_LOCK;
buf = ReadBufferWithStrategy(onerel, blkno, vac_strategy);
/* We need buffer cleanup lock so that we can prune HOT chains. */
LockBufferForCleanup(buf);
page = BufferGetPage(buf);
if (PageIsNew(page))
{
/*
* An all-zeroes page could be left over if a backend extends the
* relation but crashes before initializing the page. Reclaim such
* pages for use.
*
* We have to be careful here because we could be looking at a
* page that someone has just added to the relation and not yet
* been able to initialize (see RelationGetBufferForTuple). To
* protect against that, release the buffer lock, grab the
* relation extension lock momentarily, and re-lock the buffer. If
* the page is still uninitialized by then, it must be left over
* from a crashed backend, and we can initialize it.
*
* We don't really need the relation lock when this is a new or
* temp relation, but it's probably not worth the code space to
* check that, since this surely isn't a critical path.
*
* Note: the comparable code in vacuum.c need not worry because
* it's got exclusive lock on the whole relation.
*/
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
MIRROREDLOCK_BUFMGR_UNLOCK;
/* -------- MirroredLock ---------- */
LockRelationForExtension(onerel, ExclusiveLock);
UnlockRelationForExtension(onerel, ExclusiveLock);
/* -------- MirroredLock ---------- */
MIRROREDLOCK_BUFMGR_LOCK;
LockBufferForCleanup(buf);
if (PageIsNew(page))
{
ereport(WARNING,
(errmsg("relation \"%s\" page %u is uninitialized --- fixing",
relname, blkno)));
PageInit(page, BufferGetPageSize(buf), 0);
/* must record in xlog so that changetracking will know about this change */
log_heap_newpage(onerel, page, blkno);
empty_pages++;
lazy_record_free_space(vacrelstats, blkno,
PageGetHeapFreeSpace(page));
}
MarkBufferDirty(buf);
UnlockReleaseBuffer(buf);
MIRROREDLOCK_BUFMGR_UNLOCK;
/* -------- MirroredLock ---------- */
continue;
}
if (PageIsEmpty(page))
{
empty_pages++;
lazy_record_free_space(vacrelstats, blkno,
PageGetHeapFreeSpace(page));
UnlockReleaseBuffer(buf);
MIRROREDLOCK_BUFMGR_UNLOCK;
/* -------- MirroredLock ---------- */
continue;
}
/*
* Prune all HOT-update chains in this page.
*
* We count tuples removed by the pruning step as removed by VACUUM.
*/
tups_vacuumed += heap_page_prune(onerel, buf, OldestXmin,
false, false);
/*
* Now scan the page to collect vacuumable items and check for tuples
* requiring freezing.
*/
nfrozen = 0;
hastup = false;
prev_dead_count = vacrelstats->num_dead_tuples;
maxoff = PageGetMaxOffsetNumber(page);
for (offnum = FirstOffsetNumber;
offnum <= maxoff;
offnum = OffsetNumberNext(offnum))
{
ItemId itemid;
itemid = PageGetItemId(page, offnum);
/* Unused items require no processing, but we count 'em */
if (!ItemIdIsUsed(itemid))
{
nunused += 1;
continue;
}
/* Redirect items mustn't be touched */
if (ItemIdIsRedirected(itemid))
{
hastup = true; /* this page won't be truncatable */
continue;
}
ItemPointerSet(&(tuple.t_self), blkno, offnum);
/*
* DEAD item pointers are to be vacuumed normally; but we don't
* count them in tups_vacuumed, else we'd be double-counting (at
* least in the common case where heap_page_prune() just freed up
* a non-HOT tuple).
*/
if (ItemIdIsDead(itemid))
{
lazy_record_dead_tuple(vacrelstats, &(tuple.t_self));
continue;
}
Assert(ItemIdIsNormal(itemid));
tuple.t_data = (HeapTupleHeader) PageGetItem(page, itemid);
tuple.t_len = ItemIdGetLength(itemid);
tupgone = false;
switch (HeapTupleSatisfiesVacuum(onerel, tuple.t_data, OldestXmin, buf))
{
case HEAPTUPLE_DEAD:
/*
* Ordinarily, DEAD tuples would have been removed by
* heap_page_prune(), but it's possible that the tuple
* state changed since heap_page_prune() looked. In
* particular an INSERT_IN_PROGRESS tuple could have
* changed to DEAD if the inserter aborted. So this
* cannot be considered an error condition.
*
* If the tuple is HOT-updated then it must only be
* removed by a prune operation; so we keep it just as if
* it were RECENTLY_DEAD. Also, if it's a heap-only
* tuple, we choose to keep it, because it'll be a lot
* cheaper to get rid of it in the next pruning pass than
* to treat it like an indexed tuple.
*/
if (HeapTupleIsHotUpdated(&tuple) ||
HeapTupleIsHeapOnly(&tuple))
nkeep += 1;
else
tupgone = true; /* we can delete the tuple */
break;
case HEAPTUPLE_LIVE:
/* Tuple is good --- but let's do some validity checks */
if (onerel->rd_rel->relhasoids &&
!OidIsValid(HeapTupleGetOid(&tuple)))
elog(WARNING, "relation \"%s\" TID %u/%u: OID is invalid",
relname, blkno, offnum);
break;
case HEAPTUPLE_RECENTLY_DEAD:
/*
* If tuple is recently deleted then we must not remove it
* from relation.
*/
nkeep += 1;
break;
case HEAPTUPLE_INSERT_IN_PROGRESS:
/* This is an expected case during concurrent vacuum */
break;
case HEAPTUPLE_DELETE_IN_PROGRESS:
/* This is an expected case during concurrent vacuum */
break;
default:
elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result");
break;
}
if (tupgone)
{
lazy_record_dead_tuple(vacrelstats, &(tuple.t_self));
tups_vacuumed += 1;
}
else
{
num_tuples += 1;
hastup = true;
/*
* Each non-removable tuple must be checked to see if it needs
* freezing. Note we already have exclusive buffer lock.
*/
if (heap_freeze_tuple(tuple.t_data, FreezeLimit,
InvalidBuffer))
frozen[nfrozen++] = offnum;
}
} /* scan along page */
/*
* If we froze any tuples, mark the buffer dirty, and write a WAL
* record recording the changes. We must log the changes to be
* crash-safe against future truncation of CLOG.
*/
if (nfrozen > 0)
{
MarkBufferDirty(buf);
/* no XLOG for temp tables, though */
if (!onerel->rd_istemp)
{
XLogRecPtr recptr;
recptr = log_heap_freeze(onerel, buf, FreezeLimit,
frozen, nfrozen);
PageSetLSN(page, recptr);
PageSetTLI(page, ThisTimeLineID);
}
}
/*
* If there are no indexes then we can vacuum the page right now
* instead of doing a second scan.
*/
if (nindexes == 0 &&
vacrelstats->num_dead_tuples > 0)
{
/* Remove tuples from heap */
lazy_vacuum_page(onerel, blkno, buf, 0, vacrelstats);
/* Forget the now-vacuumed tuples, and press on */
vacrelstats->num_dead_tuples = 0;
vacuumed_pages++;
}
/*
* If we remembered any tuples for deletion, then the page will be
* visited again by lazy_vacuum_heap, which will compute and record
* its post-compaction free space. If not, then we're done with this
* page, so remember its free space as-is. (This path will always be
* taken if there are no indexes.)
*/
if (vacrelstats->num_dead_tuples == prev_dead_count)
{
lazy_record_free_space(vacrelstats, blkno,
PageGetHeapFreeSpace(page));
}
/* Remember the location of the last page with nonremovable tuples */
if (hastup)
vacrelstats->nonempty_pages = blkno + 1;
UnlockReleaseBuffer(buf);
MIRROREDLOCK_BUFMGR_UNLOCK;
/* -------- MirroredLock ---------- */
}
/* save stats for use later */
vacrelstats->rel_tuples = num_tuples;
vacrelstats->tuples_deleted = tups_vacuumed;
/* If any tuples need to be deleted, perform final vacuum cycle */
/* XXX put a threshold on min number of tuples here? */
if (vacrelstats->num_dead_tuples > 0)
{
/* Remove index entries */
for (i = 0; i < nindexes; i++)
{
List *extra_oids = get_oids_for_bitmap(all_extra_oids, Irel[i],
onerel, reindex_count);
lazy_vacuum_index(Irel[i],
&indstats[i],
vacrelstats,
extra_oids);
list_free(extra_oids);
}
reindex_count++;
/* Remove tuples from heap */
lazy_vacuum_heap(onerel, vacrelstats);
vacrelstats->num_index_scans++;
}
/* Do post-vacuum cleanup and statistics update for each index */
for (i = 0; i < nindexes; i++)
lazy_cleanup_index(Irel[i], indstats[i], vacrelstats, updated_stats);
/* If no indexes, make log report that lazy_vacuum_heap would've made */
if (vacuumed_pages)
ereport(elevel,
(errmsg("\"%s\": removed %.0f row versions in %u pages",
RelationGetRelationName(onerel),
tups_vacuumed, vacuumed_pages)));
ereport(elevel,
(errmsg("\"%s\": found %.0f removable, %.0f nonremovable row versions in %u pages",
RelationGetRelationName(onerel),
tups_vacuumed, num_tuples, nblocks),
errdetail("%.0f dead row versions cannot be removed yet.\n"
"There were %.0f unused item pointers.\n"
"%u pages contain useful free space.\n"
"%u pages are entirely empty.\n"
"%s.",
nkeep,
nunused,
vacrelstats->tot_free_pages,
empty_pages,
pg_rusage_show(&ru0))));
}
/*
* PageIndexMultiDelete
*
* This routine handles the case of deleting multiple tuples from an
* index page at once. It is considerably faster than a loop around
* PageIndexTupleDelete ... however, the caller *must* supply the array
* of item numbers to be deleted in item number order!
*/
void
PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
{
PageHeader phdr = (PageHeader) page;
Offset pd_lower = phdr->pd_lower;
Offset pd_upper = phdr->pd_upper;
Offset pd_special = phdr->pd_special;
itemIdSort itemidbase,
itemidptr;
ItemId lp;
int nline,
nused;
int i;
Size totallen;
Offset upper;
Size size;
unsigned offset;
int nextitm;
OffsetNumber offnum;
/*
* If there aren't very many items to delete, then retail
* PageIndexTupleDelete is the best way. Delete the items in reverse
* order so we don't have to think about adjusting item numbers for
* previous deletions.
*
* TODO: tune the magic number here
*/
if (nitems <= 2)
{
while (--nitems >= 0)
PageIndexTupleDelete(page, itemnos[nitems]);
return;
}
/*
* As with PageRepairFragmentation, paranoia seems justified.
*/
if (pd_lower < SizeOfPageHeaderData ||
pd_lower > pd_upper ||
pd_upper > pd_special ||
pd_special > BLCKSZ ||
pd_special != MAXALIGN(pd_special))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("corrupted page pointers: lower = %u, upper = %u, special = %u",
pd_lower, pd_upper, pd_special)));
/*
* Scan the item pointer array and build a list of just the ones we are
* going to keep. Notice we do not modify the page yet, since we are
* still validity-checking.
*/
nline = PageGetMaxOffsetNumber(page);
itemidbase = (itemIdSort) palloc(sizeof(itemIdSortData) * nline);
itemidptr = itemidbase;
totallen = 0;
nused = 0;
nextitm = 0;
for (offnum = FirstOffsetNumber; offnum <= nline; offnum = OffsetNumberNext(offnum))
{
lp = PageGetItemId(page, offnum);
Assert(ItemIdHasStorage(lp));
size = ItemIdGetLength(lp);
offset = ItemIdGetOffset(lp);
if (offset < pd_upper ||
(offset + size) > pd_special ||
offset != MAXALIGN(offset))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("corrupted item pointer: offset = %u, size = %u",
offset, (unsigned int) size)));
if (nextitm < nitems && offnum == itemnos[nextitm])
{
/* skip item to be deleted */
nextitm++;
}
else
{
itemidptr->offsetindex = nused; /* where it will go */
itemidptr->itemoff = offset;
itemidptr->olditemid = *lp;
itemidptr->alignedlen = MAXALIGN(size);
totallen += itemidptr->alignedlen;
itemidptr++;
nused++;
}
}
/* this will catch invalid or out-of-order itemnos[] */
if (nextitm != nitems)
elog(ERROR, "incorrect index offsets supplied");
if (totallen > (Size) (pd_special - pd_lower))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("corrupted item lengths: total %u, available space %u",
(unsigned int) totallen, pd_special - pd_lower)));
/* sort itemIdSortData array into decreasing itemoff order */
qsort((char *) itemidbase, nused, sizeof(itemIdSortData),
itemoffcompare);
/* compactify page and install new itemids */
upper = pd_special;
for (i = 0, itemidptr = itemidbase; i < nused; i++, itemidptr++)
{
lp = PageGetItemId(page, itemidptr->offsetindex + 1);
upper -= itemidptr->alignedlen;
memmove((char *) page + upper,
(char *) page + itemidptr->itemoff,
itemidptr->alignedlen);
*lp = itemidptr->olditemid;
lp->lp_off = upper;
}
phdr->pd_lower = SizeOfPageHeaderData + nused * sizeof(ItemIdData);
phdr->pd_upper = upper;
pfree(itemidbase);
}
/*
* Place tuple and split page, original buffer(lbuf) leaves untouched,
* returns shadow pages filled with new data.
* Tuples are distributed between pages by equal size on its, not
* an equal number!
*/
static void
entrySplitPage(GinBtree btree, Buffer origbuf,
GinBtreeStack *stack,
void *insertPayload,
BlockNumber updateblkno,
Page *newlpage, Page *newrpage)
{
GinBtreeEntryInsertData *insertData = insertPayload;
OffsetNumber off = stack->off;
OffsetNumber i,
maxoff,
separator = InvalidOffsetNumber;
Size totalsize = 0;
Size lsize = 0,
size;
char *ptr;
IndexTuple itup;
Page page;
Page lpage = PageGetTempPageCopy(BufferGetPage(origbuf));
Page rpage = PageGetTempPageCopy(BufferGetPage(origbuf));
Size pageSize = PageGetPageSize(lpage);
char tupstore[2 * BLCKSZ];
entryPreparePage(btree, lpage, off, insertData, updateblkno);
/*
* First, append all the existing tuples and the new tuple we're inserting
* one after another in a temporary workspace.
*/
maxoff = PageGetMaxOffsetNumber(lpage);
ptr = tupstore;
for (i = FirstOffsetNumber; i <= maxoff; i++)
{
if (i == off)
{
size = MAXALIGN(IndexTupleSize(insertData->entry));
memcpy(ptr, insertData->entry, size);
ptr += size;
totalsize += size + sizeof(ItemIdData);
}
itup = (IndexTuple) PageGetItem(lpage, PageGetItemId(lpage, i));
size = MAXALIGN(IndexTupleSize(itup));
memcpy(ptr, itup, size);
ptr += size;
totalsize += size + sizeof(ItemIdData);
}
if (off == maxoff + 1)
{
size = MAXALIGN(IndexTupleSize(insertData->entry));
memcpy(ptr, insertData->entry, size);
ptr += size;
totalsize += size + sizeof(ItemIdData);
}
/*
* Initialize the left and right pages, and copy all the tuples back to
* them.
*/
GinInitPage(rpage, GinPageGetOpaque(lpage)->flags, pageSize);
GinInitPage(lpage, GinPageGetOpaque(rpage)->flags, pageSize);
ptr = tupstore;
maxoff++;
lsize = 0;
page = lpage;
for (i = FirstOffsetNumber; i <= maxoff; i++)
{
itup = (IndexTuple) ptr;
if (lsize > totalsize / 2)
{
if (separator == InvalidOffsetNumber)
separator = i - 1;
page = rpage;
}
else
{
lsize += MAXALIGN(IndexTupleSize(itup)) + sizeof(ItemIdData);
}
if (PageAddItem(page, (Item) itup, IndexTupleSize(itup), InvalidOffsetNumber, false, false) == InvalidOffsetNumber)
elog(ERROR, "failed to add item to index page in \"%s\"",
RelationGetRelationName(btree->index));
ptr += MAXALIGN(IndexTupleSize(itup));
}
*newlpage = lpage;
*newrpage = rpage;
}
/*
* lazy_scan_heap() -- scan an open heap relation
*
* This routine prunes each page in the heap, which will among other
* things truncate dead tuples to dead line pointers, defragment the
* page, and set commit status bits (see heap_page_prune). It also builds
* lists of dead tuples and pages with free space, calculates statistics
* on the number of live tuples in the heap, and marks pages as
* all-visible if appropriate. When done, or when we run low on space for
* dead-tuple TIDs, invoke vacuuming of indexes and call lazy_vacuum_heap
* to reclaim dead line pointers.
*
* If there are no indexes then we can reclaim line pointers on the fly;
* dead line pointers need only be retained until all index pointers that
* reference them have been killed.
*/
static void
lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats,
Relation *Irel, int nindexes, bool scan_all)
{
BlockNumber nblocks,
blkno;
HeapTupleData tuple;
char *relname;
BlockNumber empty_pages,
vacuumed_pages;
double num_tuples,
tups_vacuumed,
nkeep,
nunused;
IndexBulkDeleteResult **indstats;
int i;
PGRUsage ru0;
Buffer vmbuffer = InvalidBuffer;
BlockNumber next_not_all_visible_block;
bool skipping_all_visible_blocks;
pg_rusage_init(&ru0);
relname = RelationGetRelationName(onerel);
ereport(elevel,
(errmsg("vacuuming \"%s.%s\"",
get_namespace_name(RelationGetNamespace(onerel)),
relname)));
empty_pages = vacuumed_pages = 0;
num_tuples = tups_vacuumed = nkeep = nunused = 0;
indstats = (IndexBulkDeleteResult **)
palloc0(nindexes * sizeof(IndexBulkDeleteResult *));
nblocks = RelationGetNumberOfBlocks(onerel);
vacrelstats->rel_pages = nblocks;
vacrelstats->scanned_pages = 0;
vacrelstats->nonempty_pages = 0;
vacrelstats->latestRemovedXid = InvalidTransactionId;
lazy_space_alloc(vacrelstats, nblocks);
/*
* We want to skip pages that don't require vacuuming according to the
* visibility map, but only when we can skip at least SKIP_PAGES_THRESHOLD
* consecutive pages. Since we're reading sequentially, the OS should be
* doing readahead for us, so there's no gain in skipping a page now and
* then; that's likely to disable readahead and so be counterproductive.
* Also, skipping even a single page means that we can't update
* relfrozenxid, so we only want to do it if we can skip a goodly number
* of pages.
*
* Before entering the main loop, establish the invariant that
* next_not_all_visible_block is the next block number >= blkno that's not
* all-visible according to the visibility map, or nblocks if there's no
* such block. Also, we set up the skipping_all_visible_blocks flag,
* which is needed because we need hysteresis in the decision: once we've
* started skipping blocks, we may as well skip everything up to the next
* not-all-visible block.
*
* Note: if scan_all is true, we won't actually skip any pages; but we
* maintain next_not_all_visible_block anyway, so as to set up the
* all_visible_according_to_vm flag correctly for each page.
*/
for (next_not_all_visible_block = 0;
next_not_all_visible_block < nblocks;
next_not_all_visible_block++)
{
if (!visibilitymap_test(onerel, next_not_all_visible_block, &vmbuffer))
break;
vacuum_delay_point();
}
if (next_not_all_visible_block >= SKIP_PAGES_THRESHOLD)
skipping_all_visible_blocks = true;
else
skipping_all_visible_blocks = false;
for (blkno = 0; blkno < nblocks; blkno++)
{
Buffer buf;
Page page;
OffsetNumber offnum,
maxoff;
bool tupgone,
hastup;
int prev_dead_count;
OffsetNumber frozen[MaxOffsetNumber];
int nfrozen;
Size freespace;
bool all_visible_according_to_vm;
bool all_visible;
bool has_dead_tuples;
TransactionId visibility_cutoff_xid = InvalidTransactionId;
if (blkno == next_not_all_visible_block)
{
/* Time to advance next_not_all_visible_block */
for (next_not_all_visible_block++;
next_not_all_visible_block < nblocks;
next_not_all_visible_block++)
{
if (!visibilitymap_test(onerel, next_not_all_visible_block,
&vmbuffer))
break;
vacuum_delay_point();
}
/*
* We know we can't skip the current block. But set up
* skipping_all_visible_blocks to do the right thing at the
* following blocks.
*/
if (next_not_all_visible_block - blkno > SKIP_PAGES_THRESHOLD)
skipping_all_visible_blocks = true;
else
skipping_all_visible_blocks = false;
all_visible_according_to_vm = false;
}
else
{
/* Current block is all-visible */
if (skipping_all_visible_blocks && !scan_all)
continue;
all_visible_according_to_vm = true;
}
vacuum_delay_point();
/*
* If we are close to overrunning the available space for dead-tuple
* TIDs, pause and do a cycle of vacuuming before we tackle this page.
*/
if ((vacrelstats->max_dead_tuples - vacrelstats->num_dead_tuples) < MaxHeapTuplesPerPage &&
vacrelstats->num_dead_tuples > 0)
{
/*
* Before beginning index vacuuming, we release any pin we may hold
* on the visibility map page. This isn't necessary for correctness,
* but we do it anyway to avoid holding the pin across a lengthy,
* unrelated operation.
*/
if (BufferIsValid(vmbuffer))
{
ReleaseBuffer(vmbuffer);
vmbuffer = InvalidBuffer;
}
/* Log cleanup info before we touch indexes */
vacuum_log_cleanup_info(onerel, vacrelstats);
/* Remove index entries */
for (i = 0; i < nindexes; i++)
lazy_vacuum_index(Irel[i],
&indstats[i],
vacrelstats);
/* Remove tuples from heap */
lazy_vacuum_heap(onerel, vacrelstats);
/*
* Forget the now-vacuumed tuples, and press on, but be careful
* not to reset latestRemovedXid since we want that value to be
* valid.
*/
vacrelstats->num_dead_tuples = 0;
vacrelstats->num_index_scans++;
}
/*
* Pin the visibility map page in case we need to mark the page
* all-visible. In most cases this will be very cheap, because we'll
* already have the correct page pinned anyway. However, it's possible
* that (a) next_not_all_visible_block is covered by a different VM page
* than the current block or (b) we released our pin and did a cycle of
* index vacuuming.
*/
visibilitymap_pin(onerel, blkno, &vmbuffer);
buf = ReadBufferExtended(onerel, MAIN_FORKNUM, blkno,
RBM_NORMAL, vac_strategy);
/* We need buffer cleanup lock so that we can prune HOT chains. */
if (!ConditionalLockBufferForCleanup(buf))
{
/*
* If we're not scanning the whole relation to guard against XID
* wraparound, it's OK to skip vacuuming a page. The next vacuum
* will clean it up.
*/
if (!scan_all)
{
ReleaseBuffer(buf);
continue;
}
/*
* If this is a wraparound checking vacuum, then we read the page
* with share lock to see if any xids need to be frozen. If the
* page doesn't need attention we just skip and continue. If it
* does, we wait for cleanup lock.
*
* We could defer the lock request further by remembering the page
* and coming back to it later, or we could even register
* ourselves for multiple buffers and then service whichever one
* is received first. For now, this seems good enough.
*/
LockBuffer(buf, BUFFER_LOCK_SHARE);
if (!lazy_check_needs_freeze(buf))
{
UnlockReleaseBuffer(buf);
continue;
}
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
LockBufferForCleanup(buf);
/* drop through to normal processing */
}
vacrelstats->scanned_pages++;
page = BufferGetPage(buf);
if (PageIsNew(page))
{
/*
* An all-zeroes page could be left over if a backend extends the
* relation but crashes before initializing the page. Reclaim such
* pages for use.
*
* We have to be careful here because we could be looking at a
* page that someone has just added to the relation and not yet
* been able to initialize (see RelationGetBufferForTuple). To
* protect against that, release the buffer lock, grab the
* relation extension lock momentarily, and re-lock the buffer. If
* the page is still uninitialized by then, it must be left over
* from a crashed backend, and we can initialize it.
*
* We don't really need the relation lock when this is a new or
* temp relation, but it's probably not worth the code space to
* check that, since this surely isn't a critical path.
*
* Note: the comparable code in vacuum.c need not worry because
* it's got exclusive lock on the whole relation.
*/
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
LockRelationForExtension(onerel, ExclusiveLock);
UnlockRelationForExtension(onerel, ExclusiveLock);
LockBufferForCleanup(buf);
if (PageIsNew(page))
{
ereport(WARNING,
(errmsg("relation \"%s\" page %u is uninitialized --- fixing",
relname, blkno)));
PageInit(page, BufferGetPageSize(buf), 0);
empty_pages++;
}
freespace = PageGetHeapFreeSpace(page);
MarkBufferDirty(buf);
UnlockReleaseBuffer(buf);
RecordPageWithFreeSpace(onerel, blkno, freespace);
continue;
}
if (PageIsEmpty(page))
{
empty_pages++;
freespace = PageGetHeapFreeSpace(page);
/* empty pages are always all-visible */
if (!PageIsAllVisible(page))
{
PageSetAllVisible(page);
MarkBufferDirty(buf);
visibilitymap_set(onerel, blkno, InvalidXLogRecPtr, vmbuffer,
InvalidTransactionId);
}
UnlockReleaseBuffer(buf);
RecordPageWithFreeSpace(onerel, blkno, freespace);
continue;
}
/*
* Prune all HOT-update chains in this page.
*
* We count tuples removed by the pruning step as removed by VACUUM.
*/
tups_vacuumed += heap_page_prune(onerel, buf, OldestXmin, false,
&vacrelstats->latestRemovedXid);
/*
* Now scan the page to collect vacuumable items and check for tuples
* requiring freezing.
*/
all_visible = true;
has_dead_tuples = false;
nfrozen = 0;
hastup = false;
prev_dead_count = vacrelstats->num_dead_tuples;
maxoff = PageGetMaxOffsetNumber(page);
for (offnum = FirstOffsetNumber;
offnum <= maxoff;
offnum = OffsetNumberNext(offnum))
{
ItemId itemid;
itemid = PageGetItemId(page, offnum);
/* Unused items require no processing, but we count 'em */
if (!ItemIdIsUsed(itemid))
{
nunused += 1;
continue;
}
/* Redirect items mustn't be touched */
if (ItemIdIsRedirected(itemid))
{
hastup = true; /* this page won't be truncatable */
continue;
}
ItemPointerSet(&(tuple.t_self), blkno, offnum);
/*
* DEAD item pointers are to be vacuumed normally; but we don't
* count them in tups_vacuumed, else we'd be double-counting (at
* least in the common case where heap_page_prune() just freed up
* a non-HOT tuple).
*/
if (ItemIdIsDead(itemid))
{
lazy_record_dead_tuple(vacrelstats, &(tuple.t_self));
all_visible = false;
continue;
}
Assert(ItemIdIsNormal(itemid));
tuple.t_data = (HeapTupleHeader) PageGetItem(page, itemid);
tuple.t_len = ItemIdGetLength(itemid);
tupgone = false;
switch (HeapTupleSatisfiesVacuum(tuple.t_data, OldestXmin, buf))
{
case HEAPTUPLE_DEAD:
/*
* Ordinarily, DEAD tuples would have been removed by
* heap_page_prune(), but it's possible that the tuple
* state changed since heap_page_prune() looked. In
* particular an INSERT_IN_PROGRESS tuple could have
* changed to DEAD if the inserter aborted. So this
* cannot be considered an error condition.
*
* If the tuple is HOT-updated then it must only be
* removed by a prune operation; so we keep it just as if
* it were RECENTLY_DEAD. Also, if it's a heap-only
* tuple, we choose to keep it, because it'll be a lot
* cheaper to get rid of it in the next pruning pass than
* to treat it like an indexed tuple.
*/
if (HeapTupleIsHotUpdated(&tuple) ||
HeapTupleIsHeapOnly(&tuple))
nkeep += 1;
else
tupgone = true; /* we can delete the tuple */
all_visible = false;
break;
case HEAPTUPLE_LIVE:
/* Tuple is good --- but let's do some validity checks */
if (onerel->rd_rel->relhasoids &&
!OidIsValid(HeapTupleGetOid(&tuple)))
elog(WARNING, "relation \"%s\" TID %u/%u: OID is invalid",
relname, blkno, offnum);
/*
* Is the tuple definitely visible to all transactions?
*
* NB: Like with per-tuple hint bits, we can't set the
* PD_ALL_VISIBLE flag if the inserter committed
* asynchronously. See SetHintBits for more info. Check
* that the HEAP_XMIN_COMMITTED hint bit is set because of
* that.
*/
if (all_visible)
{
TransactionId xmin;
if (!(tuple.t_data->t_infomask & HEAP_XMIN_COMMITTED))
{
all_visible = false;
break;
}
/*
* The inserter definitely committed. But is it old
* enough that everyone sees it as committed?
*/
xmin = HeapTupleHeaderGetXmin(tuple.t_data);
if (!TransactionIdPrecedes(xmin, OldestXmin))
{
all_visible = false;
break;
}
/* Track newest xmin on page. */
if (TransactionIdFollows(xmin, visibility_cutoff_xid))
visibility_cutoff_xid = xmin;
}
break;
case HEAPTUPLE_RECENTLY_DEAD:
/*
* If tuple is recently deleted then we must not remove it
* from relation.
*/
nkeep += 1;
all_visible = false;
break;
case HEAPTUPLE_INSERT_IN_PROGRESS:
/* This is an expected case during concurrent vacuum */
all_visible = false;
break;
case HEAPTUPLE_DELETE_IN_PROGRESS:
/* This is an expected case during concurrent vacuum */
all_visible = false;
break;
default:
elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result");
break;
}
if (tupgone)
{
lazy_record_dead_tuple(vacrelstats, &(tuple.t_self));
HeapTupleHeaderAdvanceLatestRemovedXid(tuple.t_data,
&vacrelstats->latestRemovedXid);
tups_vacuumed += 1;
has_dead_tuples = true;
}
else
{
num_tuples += 1;
hastup = true;
/*
* Each non-removable tuple must be checked to see if it needs
* freezing. Note we already have exclusive buffer lock.
*/
if (heap_freeze_tuple(tuple.t_data, FreezeLimit))
frozen[nfrozen++] = offnum;
}
} /* scan along page */
/*
* If we froze any tuples, mark the buffer dirty, and write a WAL
* record recording the changes. We must log the changes to be
* crash-safe against future truncation of CLOG.
*/
if (nfrozen > 0)
{
MarkBufferDirty(buf);
if (RelationNeedsWAL(onerel))
{
XLogRecPtr recptr;
recptr = log_heap_freeze(onerel, buf, FreezeLimit,
frozen, nfrozen);
PageSetLSN(page, recptr);
PageSetTLI(page, ThisTimeLineID);
}
}
/*
* If there are no indexes then we can vacuum the page right now
* instead of doing a second scan.
*/
if (nindexes == 0 &&
vacrelstats->num_dead_tuples > 0)
{
/* Remove tuples from heap */
lazy_vacuum_page(onerel, blkno, buf, 0, vacrelstats);
/*
* Forget the now-vacuumed tuples, and press on, but be careful
* not to reset latestRemovedXid since we want that value to be
* valid.
*/
vacrelstats->num_dead_tuples = 0;
vacuumed_pages++;
}
freespace = PageGetHeapFreeSpace(page);
/* mark page all-visible, if appropriate */
if (all_visible && !all_visible_according_to_vm)
{
if (!PageIsAllVisible(page))
{
PageSetAllVisible(page);
MarkBufferDirty(buf);
}
visibilitymap_set(onerel, blkno, InvalidXLogRecPtr, vmbuffer,
visibility_cutoff_xid);
}
/*
* As of PostgreSQL 9.2, the visibility map bit should never be set if
* the page-level bit is clear.
*/
else if (all_visible_according_to_vm && !PageIsAllVisible(page))
{
elog(WARNING, "page is not marked all-visible but visibility map bit is set in relation \"%s\" page %u",
relname, blkno);
visibilitymap_clear(onerel, blkno, vmbuffer);
}
/*
* It's possible for the value returned by GetOldestXmin() to move
* backwards, so it's not wrong for us to see tuples that appear to
* not be visible to everyone yet, while PD_ALL_VISIBLE is already
* set. The real safe xmin value never moves backwards, but
* GetOldestXmin() is conservative and sometimes returns a value
* that's unnecessarily small, so if we see that contradiction it just
* means that the tuples that we think are not visible to everyone yet
* actually are, and the PD_ALL_VISIBLE flag is correct.
*
* There should never be dead tuples on a page with PD_ALL_VISIBLE
* set, however.
*/
else if (PageIsAllVisible(page) && has_dead_tuples)
{
elog(WARNING, "page containing dead tuples is marked as all-visible in relation \"%s\" page %u",
relname, blkno);
PageClearAllVisible(page);
MarkBufferDirty(buf);
visibilitymap_clear(onerel, blkno, vmbuffer);
}
UnlockReleaseBuffer(buf);
/* Remember the location of the last page with nonremovable tuples */
if (hastup)
vacrelstats->nonempty_pages = blkno + 1;
/*
* If we remembered any tuples for deletion, then the page will be
* visited again by lazy_vacuum_heap, which will compute and record
* its post-compaction free space. If not, then we're done with this
* page, so remember its free space as-is. (This path will always be
* taken if there are no indexes.)
*/
if (vacrelstats->num_dead_tuples == prev_dead_count)
RecordPageWithFreeSpace(onerel, blkno, freespace);
}
/* save stats for use later */
vacrelstats->scanned_tuples = num_tuples;
vacrelstats->tuples_deleted = tups_vacuumed;
/* now we can compute the new value for pg_class.reltuples */
vacrelstats->new_rel_tuples = vac_estimate_reltuples(onerel, false,
nblocks,
vacrelstats->scanned_pages,
num_tuples);
/* If any tuples need to be deleted, perform final vacuum cycle */
/* XXX put a threshold on min number of tuples here? */
if (vacrelstats->num_dead_tuples > 0)
{
/* Log cleanup info before we touch indexes */
vacuum_log_cleanup_info(onerel, vacrelstats);
/* Remove index entries */
for (i = 0; i < nindexes; i++)
lazy_vacuum_index(Irel[i],
&indstats[i],
vacrelstats);
/* Remove tuples from heap */
lazy_vacuum_heap(onerel, vacrelstats);
vacrelstats->num_index_scans++;
}
/* Release the pin on the visibility map page */
if (BufferIsValid(vmbuffer))
{
ReleaseBuffer(vmbuffer);
vmbuffer = InvalidBuffer;
}
/* Do post-vacuum cleanup and statistics update for each index */
for (i = 0; i < nindexes; i++)
lazy_cleanup_index(Irel[i], indstats[i], vacrelstats);
/* If no indexes, make log report that lazy_vacuum_heap would've made */
if (vacuumed_pages)
ereport(elevel,
(errmsg("\"%s\": removed %.0f row versions in %u pages",
RelationGetRelationName(onerel),
tups_vacuumed, vacuumed_pages)));
ereport(elevel,
(errmsg("\"%s\": found %.0f removable, %.0f nonremovable row versions in %u out of %u pages",
RelationGetRelationName(onerel),
tups_vacuumed, num_tuples,
vacrelstats->scanned_pages, nblocks),
errdetail("%.0f dead row versions cannot be removed yet.\n"
"There were %.0f unused item pointers.\n"
"%u pages are entirely empty.\n"
"%s.",
nkeep,
nunused,
empty_pages,
pg_rusage_show(&ru0))));
}
/*
* bitgetpage - subroutine for BitmapHeapNext()
*
* This routine reads and pins the specified page of the relation, then
* builds an array indicating which tuples on the page are both potentially
* interesting according to the bitmap, and visible according to the snapshot.
*/
static void
bitgetpage(HeapScanDesc scan, TBMIterateResult *tbmres)
{
BlockNumber page = tbmres->blockno;
Buffer buffer;
Snapshot snapshot;
int ntup;
/*
* Acquire pin on the target heap page, trading in any pin we held before.
*/
Assert(page < scan->rs_nblocks);
scan->rs_cbuf = ReleaseAndReadBuffer(scan->rs_cbuf,
scan->rs_rd,
page);
buffer = scan->rs_cbuf;
snapshot = scan->rs_snapshot;
ntup = 0;
/*
* Prune and repair fragmentation for the whole page, if possible.
*/
heap_page_prune_opt(scan->rs_rd, buffer);
/*
* We must hold share lock on the buffer content while examining tuple
* visibility. Afterwards, however, the tuples we have found to be
* visible are guaranteed good as long as we hold the buffer pin.
*/
LockBuffer(buffer, BUFFER_LOCK_SHARE);
/*
* We need two separate strategies for lossy and non-lossy cases.
*/
if (tbmres->ntuples >= 0)
{
/*
* Bitmap is non-lossy, so we just look through the offsets listed in
* tbmres; but we have to follow any HOT chain starting at each such
* offset.
*/
int curslot;
for (curslot = 0; curslot < tbmres->ntuples; curslot++)
{
OffsetNumber offnum = tbmres->offsets[curslot];
ItemPointerData tid;
HeapTupleData heapTuple;
ItemPointerSet(&tid, page, offnum);
if (heap_hot_search_buffer(&tid, scan->rs_rd, buffer, snapshot,
&heapTuple, NULL, true))
scan->rs_vistuples[ntup++] = ItemPointerGetOffsetNumber(&tid);
}
}
else
{
/*
* Bitmap is lossy, so we must examine each item pointer on the page.
* But we can ignore HOT chains, since we'll check each tuple anyway.
*/
Page dp = (Page) BufferGetPage(buffer);
OffsetNumber maxoff = PageGetMaxOffsetNumber(dp);
OffsetNumber offnum;
for (offnum = FirstOffsetNumber; offnum <= maxoff; offnum = OffsetNumberNext(offnum))
{
ItemId lp;
HeapTupleData loctup;
bool valid;
lp = PageGetItemId(dp, offnum);
if (!ItemIdIsNormal(lp))
continue;
loctup.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
loctup.t_len = ItemIdGetLength(lp);
loctup.t_tableOid = scan->rs_rd->rd_id;
ItemPointerSet(&loctup.t_self, page, offnum);
valid = HeapTupleSatisfiesVisibility(&loctup, snapshot, buffer);
if (valid)
{
scan->rs_vistuples[ntup++] = offnum;
PredicateLockTuple(scan->rs_rd, &loctup, snapshot);
}
CheckForSerializableConflictOut(valid, scan->rs_rd, &loctup,
buffer, snapshot);
}
}
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
Assert(ntup <= MaxHeapTuplesPerPage);
scan->rs_ntuples = ntup;
}
/*
* _bt_pagedel() -- Delete a page from the b-tree, if legal to do so.
*
* This action unlinks the page from the b-tree structure, removing all
* pointers leading to it --- but not touching its own left and right links.
* The page cannot be physically reclaimed right away, since other processes
* may currently be trying to follow links leading to the page; they have to
* be allowed to use its right-link to recover. See nbtree/README.
*
* On entry, the target buffer must be pinned and locked (either read or write
* lock is OK). This lock and pin will be dropped before exiting.
*
* The "stack" argument can be a search stack leading (approximately) to the
* target page, or NULL --- outside callers typically pass NULL since they
* have not done such a search, but internal recursion cases pass the stack
* to avoid duplicated search effort.
*
* Returns the number of pages successfully deleted (zero if page cannot
* be deleted now; could be more than one if parent pages were deleted too).
*
* NOTE: this leaks memory. Rather than trying to clean up everything
* carefully, it's better to run it in a temp context that can be reset
* frequently.
*/
int
_bt_pagedel(Relation rel, Buffer buf, BTStack stack)
{
int result;
BlockNumber target,
leftsib,
rightsib,
parent;
OffsetNumber poffset,
maxoff;
uint32 targetlevel,
ilevel;
ItemId itemid;
IndexTuple targetkey,
itup;
ScanKey itup_scankey;
Buffer lbuf,
rbuf,
pbuf;
bool parent_half_dead;
bool parent_one_child;
bool rightsib_empty;
Buffer metabuf = InvalidBuffer;
Page metapg = NULL;
BTMetaPageData *metad = NULL;
Page page;
BTPageOpaque opaque;
/*
* We can never delete rightmost pages nor root pages. While at it, check
* that page is not already deleted and is empty.
*/
page = BufferGetPage(buf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
if (P_RIGHTMOST(opaque) || P_ISROOT(opaque) || P_ISDELETED(opaque) ||
P_FIRSTDATAKEY(opaque) <= PageGetMaxOffsetNumber(page))
{
/* Should never fail to delete a half-dead page */
Assert(!P_ISHALFDEAD(opaque));
_bt_relbuf(rel, buf);
return 0;
}
/*
* Save info about page, including a copy of its high key (it must have
* one, being non-rightmost).
*/
target = BufferGetBlockNumber(buf);
targetlevel = opaque->btpo.level;
leftsib = opaque->btpo_prev;
itemid = PageGetItemId(page, P_HIKEY);
targetkey = CopyIndexTuple((IndexTuple) PageGetItem(page, itemid));
/*
* To avoid deadlocks, we'd better drop the target page lock before going
* further.
*/
_bt_relbuf(rel, buf);
/*
* We need an approximate pointer to the page's parent page. We use the
* standard search mechanism to search for the page's high key; this will
* give us a link to either the current parent or someplace to its left
* (if there are multiple equal high keys). In recursion cases, the
* caller already generated a search stack and we can just re-use that
* work.
*/
if (stack == NULL)
{
if (!InRecovery)
{
/* we need an insertion scan key to do our search, so build one */
itup_scankey = _bt_mkscankey(rel, targetkey);
/* find the leftmost leaf page containing this key */
stack = _bt_search(rel, rel->rd_rel->relnatts, itup_scankey, false,
&lbuf, BT_READ);
/* don't need a pin on that either */
_bt_relbuf(rel, lbuf);
/*
* If we are trying to delete an interior page, _bt_search did
* more than we needed. Locate the stack item pointing to our
* parent level.
*/
ilevel = 0;
for (;;)
{
if (stack == NULL)
elog(ERROR, "not enough stack items");
if (ilevel == targetlevel)
break;
stack = stack->bts_parent;
ilevel++;
}
}
else
{
/*
* During WAL recovery, we can't use _bt_search (for one reason,
* it might invoke user-defined comparison functions that expect
* facilities not available in recovery mode). Instead, just set
* up a dummy stack pointing to the left end of the parent tree
* level, from which _bt_getstackbuf will walk right to the parent
* page. Painful, but we don't care too much about performance in
* this scenario.
*/
pbuf = _bt_get_endpoint(rel, targetlevel + 1, false);
stack = (BTStack) palloc(sizeof(BTStackData));
stack->bts_blkno = BufferGetBlockNumber(pbuf);
stack->bts_offset = InvalidOffsetNumber;
/* bts_btentry will be initialized below */
stack->bts_parent = NULL;
_bt_relbuf(rel, pbuf);
}
}
/*
* We cannot delete a page that is the rightmost child of its immediate
* parent, unless it is the only child --- in which case the parent has to
* be deleted too, and the same condition applies recursively to it. We
* have to check this condition all the way up before trying to delete. We
* don't need to re-test when deleting a non-leaf page, though.
*/
if (targetlevel == 0 &&
!_bt_parent_deletion_safe(rel, target, stack))
return 0;
/*
* We have to lock the pages we need to modify in the standard order:
* moving right, then up. Else we will deadlock against other writers.
*
* So, we need to find and write-lock the current left sibling of the
* target page. The sibling that was current a moment ago could have
* split, so we may have to move right. This search could fail if either
* the sibling or the target page was deleted by someone else meanwhile;
* if so, give up. (Right now, that should never happen, since page
* deletion is only done in VACUUM and there shouldn't be multiple VACUUMs
* concurrently on the same table.)
*/
if (leftsib != P_NONE)
{
lbuf = _bt_getbuf(rel, leftsib, BT_WRITE);
page = BufferGetPage(lbuf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
while (P_ISDELETED(opaque) || opaque->btpo_next != target)
{
/* step right one page */
leftsib = opaque->btpo_next;
_bt_relbuf(rel, lbuf);
if (leftsib == P_NONE)
{
elog(LOG, "no left sibling (concurrent deletion?) in \"%s\"",
RelationGetRelationName(rel));
return 0;
}
lbuf = _bt_getbuf(rel, leftsib, BT_WRITE);
page = BufferGetPage(lbuf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
}
}
else
lbuf = InvalidBuffer;
/*
* Next write-lock the target page itself. It should be okay to take just
* a write lock not a superexclusive lock, since no scans would stop on an
* empty page.
*/
buf = _bt_getbuf(rel, target, BT_WRITE);
page = BufferGetPage(buf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
/*
* Check page is still empty etc, else abandon deletion. The empty check
* is necessary since someone else might have inserted into it while we
* didn't have it locked; the others are just for paranoia's sake.
*/
if (P_RIGHTMOST(opaque) || P_ISROOT(opaque) || P_ISDELETED(opaque) ||
P_FIRSTDATAKEY(opaque) <= PageGetMaxOffsetNumber(page))
{
_bt_relbuf(rel, buf);
if (BufferIsValid(lbuf))
_bt_relbuf(rel, lbuf);
return 0;
}
if (opaque->btpo_prev != leftsib)
elog(ERROR, "left link changed unexpectedly in block %u of index \"%s\"",
target, RelationGetRelationName(rel));
/*
* And next write-lock the (current) right sibling.
*/
rightsib = opaque->btpo_next;
rbuf = _bt_getbuf(rel, rightsib, BT_WRITE);
page = BufferGetPage(rbuf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
if (opaque->btpo_prev != target)
elog(ERROR, "right sibling's left-link doesn't match: "
"block %u links to %u instead of expected %u in index \"%s\"",
rightsib, opaque->btpo_prev, target,
RelationGetRelationName(rel));
/*
* Next find and write-lock the current parent of the target page. This is
* essentially the same as the corresponding step of splitting.
*/
ItemPointerSet(&(stack->bts_btentry.t_tid), target, P_HIKEY);
pbuf = _bt_getstackbuf(rel, stack, BT_WRITE);
if (pbuf == InvalidBuffer)
elog(ERROR, "failed to re-find parent key in index \"%s\" for deletion target page %u",
RelationGetRelationName(rel), target);
parent = stack->bts_blkno;
poffset = stack->bts_offset;
/*
* If the target is the rightmost child of its parent, then we can't
* delete, unless it's also the only child --- in which case the parent
* changes to half-dead status. The "can't delete" case should have been
* detected by _bt_parent_deletion_safe, so complain if we see it now.
*/
page = BufferGetPage(pbuf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
maxoff = PageGetMaxOffsetNumber(page);
parent_half_dead = false;
parent_one_child = false;
if (poffset >= maxoff)
{
if (poffset == P_FIRSTDATAKEY(opaque))
parent_half_dead = true;
else
elog(ERROR, "failed to delete rightmost child %u of block %u in index \"%s\"",
target, parent, RelationGetRelationName(rel));
}
else
{
/* Will there be exactly one child left in this parent? */
if (OffsetNumberNext(P_FIRSTDATAKEY(opaque)) == maxoff)
parent_one_child = true;
}
/*
* If we are deleting the next-to-last page on the target's level, then
* the rightsib is a candidate to become the new fast root. (In theory, it
* might be possible to push the fast root even further down, but the odds
* of doing so are slim, and the locking considerations daunting.)
*
* We don't support handling this in the case where the parent is becoming
* half-dead, even though it theoretically could occur.
*
* We can safely acquire a lock on the metapage here --- see comments for
* _bt_newroot().
*/
if (leftsib == P_NONE && !parent_half_dead)
{
page = BufferGetPage(rbuf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
Assert(opaque->btpo.level == targetlevel);
if (P_RIGHTMOST(opaque))
{
/* rightsib will be the only one left on the level */
metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_WRITE);
metapg = BufferGetPage(metabuf);
metad = BTPageGetMeta(metapg);
/*
* The expected case here is btm_fastlevel == targetlevel+1; if
* the fastlevel is <= targetlevel, something is wrong, and we
* choose to overwrite it to fix it.
*/
if (metad->btm_fastlevel > targetlevel + 1)
{
/* no update wanted */
_bt_relbuf(rel, metabuf);
metabuf = InvalidBuffer;
}
}
}
/*
* Check that the parent-page index items we're about to delete/overwrite
* contain what we expect. This can fail if the index has become
* corrupt for some reason. We want to throw any error before entering
* the critical section --- otherwise it'd be a PANIC.
*
* The test on the target item is just an Assert because _bt_getstackbuf
* should have guaranteed it has the expected contents. The test on the
* next-child downlink is known to sometimes fail in the field, though.
*/
page = BufferGetPage(pbuf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
#ifdef USE_ASSERT_CHECKING
itemid = PageGetItemId(page, poffset);
itup = (IndexTuple) PageGetItem(page, itemid);
Assert(ItemPointerGetBlockNumber(&(itup->t_tid)) == target);
#endif
if (!parent_half_dead)
{
OffsetNumber nextoffset;
nextoffset = OffsetNumberNext(poffset);
itemid = PageGetItemId(page, nextoffset);
itup = (IndexTuple) PageGetItem(page, itemid);
if (ItemPointerGetBlockNumber(&(itup->t_tid)) != rightsib)
elog(ERROR, "right sibling %u of block %u is not next child %u of block %u in index \"%s\"",
rightsib, target, ItemPointerGetBlockNumber(&(itup->t_tid)),
parent, RelationGetRelationName(rel));
}
/*
* Here we begin doing the deletion.
*/
/* No ereport(ERROR) until changes are logged */
START_CRIT_SECTION();
/*
* Update parent. The normal case is a tad tricky because we want to
* delete the target's downlink and the *following* key. Easiest way is
* to copy the right sibling's downlink over the target downlink, and then
* delete the following item.
*/
if (parent_half_dead)
{
PageIndexTupleDelete(page, poffset);
opaque->btpo_flags |= BTP_HALF_DEAD;
}
else
{
OffsetNumber nextoffset;
itemid = PageGetItemId(page, poffset);
itup = (IndexTuple) PageGetItem(page, itemid);
ItemPointerSet(&(itup->t_tid), rightsib, P_HIKEY);
nextoffset = OffsetNumberNext(poffset);
PageIndexTupleDelete(page, nextoffset);
}
/*
* Update siblings' side-links. Note the target page's side-links will
* continue to point to the siblings. Asserts here are just rechecking
* things we already verified above.
*/
if (BufferIsValid(lbuf))
{
page = BufferGetPage(lbuf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
Assert(opaque->btpo_next == target);
opaque->btpo_next = rightsib;
}
page = BufferGetPage(rbuf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
Assert(opaque->btpo_prev == target);
opaque->btpo_prev = leftsib;
rightsib_empty = (P_FIRSTDATAKEY(opaque) > PageGetMaxOffsetNumber(page));
/*
* Mark the page itself deleted. It can be recycled when all current
* transactions are gone.
*/
page = BufferGetPage(buf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
opaque->btpo_flags &= ~BTP_HALF_DEAD;
opaque->btpo_flags |= BTP_DELETED;
opaque->btpo.xact = ReadNewTransactionId();
/* And update the metapage, if needed */
if (BufferIsValid(metabuf))
{
metad->btm_fastroot = rightsib;
metad->btm_fastlevel = targetlevel;
MarkBufferDirty(metabuf);
}
/* Must mark buffers dirty before XLogInsert */
MarkBufferDirty(pbuf);
MarkBufferDirty(rbuf);
MarkBufferDirty(buf);
if (BufferIsValid(lbuf))
MarkBufferDirty(lbuf);
/* XLOG stuff */
if (!rel->rd_istemp)
{
xl_btree_delete_page xlrec;
xl_btree_metadata xlmeta;
uint8 xlinfo;
XLogRecPtr recptr;
XLogRecData rdata[5];
XLogRecData *nextrdata;
xlrec.target.node = rel->rd_node;
ItemPointerSet(&(xlrec.target.tid), parent, poffset);
xlrec.deadblk = target;
xlrec.leftblk = leftsib;
xlrec.rightblk = rightsib;
xlrec.btpo_xact = opaque->btpo.xact;
rdata[0].data = (char *) &xlrec;
rdata[0].len = SizeOfBtreeDeletePage;
rdata[0].buffer = InvalidBuffer;
rdata[0].next = nextrdata = &(rdata[1]);
if (BufferIsValid(metabuf))
{
xlmeta.root = metad->btm_root;
xlmeta.level = metad->btm_level;
xlmeta.fastroot = metad->btm_fastroot;
xlmeta.fastlevel = metad->btm_fastlevel;
nextrdata->data = (char *) &xlmeta;
nextrdata->len = sizeof(xl_btree_metadata);
nextrdata->buffer = InvalidBuffer;
nextrdata->next = nextrdata + 1;
nextrdata++;
xlinfo = XLOG_BTREE_DELETE_PAGE_META;
}
else if (parent_half_dead)
xlinfo = XLOG_BTREE_DELETE_PAGE_HALF;
else
xlinfo = XLOG_BTREE_DELETE_PAGE;
nextrdata->data = NULL;
nextrdata->len = 0;
nextrdata->next = nextrdata + 1;
nextrdata->buffer = pbuf;
nextrdata->buffer_std = true;
nextrdata++;
nextrdata->data = NULL;
nextrdata->len = 0;
nextrdata->buffer = rbuf;
nextrdata->buffer_std = true;
nextrdata->next = NULL;
if (BufferIsValid(lbuf))
{
nextrdata->next = nextrdata + 1;
nextrdata++;
nextrdata->data = NULL;
nextrdata->len = 0;
nextrdata->buffer = lbuf;
nextrdata->buffer_std = true;
nextrdata->next = NULL;
}
recptr = XLogInsert(RM_BTREE_ID, xlinfo, rdata);
if (BufferIsValid(metabuf))
{
PageSetLSN(metapg, recptr);
PageSetTLI(metapg, ThisTimeLineID);
}
page = BufferGetPage(pbuf);
PageSetLSN(page, recptr);
PageSetTLI(page, ThisTimeLineID);
page = BufferGetPage(rbuf);
PageSetLSN(page, recptr);
PageSetTLI(page, ThisTimeLineID);
page = BufferGetPage(buf);
PageSetLSN(page, recptr);
PageSetTLI(page, ThisTimeLineID);
if (BufferIsValid(lbuf))
{
page = BufferGetPage(lbuf);
PageSetLSN(page, recptr);
PageSetTLI(page, ThisTimeLineID);
}
}
END_CRIT_SECTION();
/* release metapage; send out relcache inval if metapage changed */
if (BufferIsValid(metabuf))
{
CacheInvalidateRelcache(rel);
_bt_relbuf(rel, metabuf);
}
/* can always release leftsib immediately */
if (BufferIsValid(lbuf))
_bt_relbuf(rel, lbuf);
/*
* If parent became half dead, recurse to delete it. Otherwise, if right
* sibling is empty and is now the last child of the parent, recurse to
* try to delete it. (These cases cannot apply at the same time, though
* the second case might itself recurse to the first.)
*
* When recursing to parent, we hold the lock on the target page until
* done. This delays any insertions into the keyspace that was just
* effectively reassigned to the parent's right sibling. If we allowed
* that, and there were enough such insertions before we finish deleting
* the parent, page splits within that keyspace could lead to inserting
* out-of-order keys into the grandparent level. It is thought that that
* wouldn't have any serious consequences, but it still seems like a
* pretty bad idea.
*/
if (parent_half_dead)
{
/* recursive call will release pbuf */
_bt_relbuf(rel, rbuf);
result = _bt_pagedel(rel, pbuf, stack->bts_parent) + 1;
_bt_relbuf(rel, buf);
}
else if (parent_one_child && rightsib_empty)
{
_bt_relbuf(rel, pbuf);
_bt_relbuf(rel, buf);
/* recursive call will release rbuf */
result = _bt_pagedel(rel, rbuf, stack) + 1;
}
else
{
_bt_relbuf(rel, pbuf);
_bt_relbuf(rel, buf);
_bt_relbuf(rel, rbuf);
result = 1;
}
return result;
}
/*
* _hash_first() -- Find the first item in a scan.
*
* Find the first item in the index that
* satisfies the qualification associated with the scan descriptor. On
* success, the page containing the current index tuple is read locked
* and pinned, and the scan's opaque data entry is updated to
* include the buffer.
*/
bool
_hash_first(IndexScanDesc scan, ScanDirection dir)
{
Relation rel = scan->indexRelation;
HashScanOpaque so = (HashScanOpaque) scan->opaque;
ScanKey cur;
uint32 hashkey;
Bucket bucket;
BlockNumber blkno;
Buffer buf;
Buffer metabuf;
Page page;
HashPageOpaque opaque;
HashMetaPage metap;
IndexTuple itup;
ItemPointer current;
OffsetNumber offnum;
pgstat_count_index_scan(rel);
current = &(so->hashso_curpos);
ItemPointerSetInvalid(current);
/*
* We do not support hash scans with no index qualification, because we
* would have to read the whole index rather than just one bucket. That
* creates a whole raft of problems, since we haven't got a practical way
* to lock all the buckets against splits or compactions.
*/
if (scan->numberOfKeys < 1)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("hash indexes do not support whole-index scans")));
/* There may be more than one index qual, but we hash only the first */
cur = &scan->keyData[0];
/* We support only single-column hash indexes */
Assert(cur->sk_attno == 1);
/* And there's only one operator strategy, too */
Assert(cur->sk_strategy == HTEqualStrategyNumber);
/*
* If the constant in the index qual is NULL, assume it cannot match any
* items in the index.
*/
if (cur->sk_flags & SK_ISNULL)
return false;
/*
* Okay to compute the hash key. We want to do this before acquiring any
* locks, in case a user-defined hash function happens to be slow.
*
* If scankey operator is not a cross-type comparison, we can use the
* cached hash function; otherwise gotta look it up in the catalogs.
*
* We support the convention that sk_subtype == InvalidOid means the
* opclass input type; this is a hack to simplify life for ScanKeyInit().
*/
if (cur->sk_subtype == rel->rd_opcintype[0] ||
cur->sk_subtype == InvalidOid)
hashkey = _hash_datum2hashkey(rel, cur->sk_argument);
else
hashkey = _hash_datum2hashkey_type(rel, cur->sk_argument,
cur->sk_subtype);
so->hashso_sk_hash = hashkey;
/*
* Acquire shared split lock so we can compute the target bucket safely
* (see README).
*/
_hash_getlock(rel, 0, HASH_SHARE);
/* Read the metapage */
metabuf = _hash_getbuf(rel, HASH_METAPAGE, HASH_READ, LH_META_PAGE);
metap = HashPageGetMeta(BufferGetPage(metabuf));
/*
* Compute the target bucket number, and convert to block number.
*/
bucket = _hash_hashkey2bucket(hashkey,
metap->hashm_maxbucket,
metap->hashm_highmask,
metap->hashm_lowmask);
blkno = BUCKET_TO_BLKNO(metap, bucket);
/* done with the metapage */
_hash_relbuf(rel, metabuf);
/*
* Acquire share lock on target bucket; then we can release split lock.
*/
_hash_getlock(rel, blkno, HASH_SHARE);
_hash_droplock(rel, 0, HASH_SHARE);
/* Update scan opaque state to show we have lock on the bucket */
so->hashso_bucket = bucket;
so->hashso_bucket_valid = true;
so->hashso_bucket_blkno = blkno;
/* Fetch the primary bucket page for the bucket */
buf = _hash_getbuf(rel, blkno, HASH_READ, LH_BUCKET_PAGE);
page = BufferGetPage(buf);
opaque = (HashPageOpaque) PageGetSpecialPointer(page);
Assert(opaque->hasho_bucket == bucket);
/* If a backwards scan is requested, move to the end of the chain */
if (ScanDirectionIsBackward(dir))
{
while (BlockNumberIsValid(opaque->hasho_nextblkno))
_hash_readnext(rel, &buf, &page, &opaque);
}
/* Now find the first tuple satisfying the qualification */
if (!_hash_step(scan, &buf, dir))
return false;
/* if we're here, _hash_step found a valid tuple */
offnum = ItemPointerGetOffsetNumber(current);
_hash_checkpage(rel, buf, LH_BUCKET_PAGE | LH_OVERFLOW_PAGE);
page = BufferGetPage(buf);
itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, offnum));
so->hashso_heappos = itup->t_tid;
return true;
}
/**
* @brief Create LoadStatus file and load heap tuples directly.
* @return void
*/
static void
DirectWriterInsert(DirectWriter *self, HeapTuple tuple)
{
Page page;
OffsetNumber offnum;
ItemId itemId;
Item item;
LoadStatus *ls = &self->ls;
/* Compress the tuple data if needed. */
if (tuple->t_len > TOAST_TUPLE_THRESHOLD)
tuple = toast_insert_or_update(self->base.rel, tuple, NULL, 0);
BULKLOAD_PROFILE(&prof_writer_toast);
/* Assign oids if needed. */
if (self->base.rel->rd_rel->relhasoids)
{
Assert(!OidIsValid(HeapTupleGetOid(tuple)));
HeapTupleSetOid(tuple, GetNewOid(self->base.rel));
}
/* Assume the tuple has been toasted already. */
if (MAXALIGN(tuple->t_len) > MaxHeapTupleSize)
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("row is too big: size %lu, maximum size %lu",
(unsigned long) tuple->t_len,
(unsigned long) MaxHeapTupleSize)));
/* Fill current page, or go to next page if the page is full. */
page = GetCurrentPage(self);
if (PageGetFreeSpace(page) < MAXALIGN(tuple->t_len) +
RelationGetTargetPageFreeSpace(self->base.rel, HEAP_DEFAULT_FILLFACTOR))
{
if (self->curblk < BLOCK_BUF_NUM - 1)
self->curblk++;
else
{
flush_pages(self);
self->curblk = 0; /* recycle from first block */
}
page = GetCurrentPage(self);
/* Initialize current block */
PageInit(page, BLCKSZ, 0);
PageSetTLI(page, ThisTimeLineID);
}
tuple->t_data->t_infomask &= ~(HEAP_XACT_MASK);
tuple->t_data->t_infomask2 &= ~(HEAP2_XACT_MASK);
tuple->t_data->t_infomask |= HEAP_XMAX_INVALID;
HeapTupleHeaderSetXmin(tuple->t_data, self->xid);
HeapTupleHeaderSetCmin(tuple->t_data, self->cid);
HeapTupleHeaderSetXmax(tuple->t_data, 0);
/* put the tuple on local page. */
offnum = PageAddItem(page, (Item) tuple->t_data,
tuple->t_len, InvalidOffsetNumber, false, true);
ItemPointerSet(&(tuple->t_self), LS_TOTAL_CNT(ls) + self->curblk, offnum);
itemId = PageGetItemId(page, offnum);
item = PageGetItem(page, itemId);
((HeapTupleHeader) item)->t_ctid = tuple->t_self;
BULKLOAD_PROFILE(&prof_writer_table);
SpoolerInsert(&self->spooler, tuple);
BULKLOAD_PROFILE(&prof_writer_index);
}
/*
* Workhouse routine for doing insertion into a GiST index. Note that
* this routine assumes it is invoked in a short-lived memory context,
* so it does not bother releasing palloc'd allocations.
*/
void
gistdoinsert(Relation r, IndexTuple itup, Size freespace, GISTSTATE *giststate)
{
ItemId iid;
IndexTuple idxtuple;
GISTInsertStack firststack;
GISTInsertStack *stack;
GISTInsertState state;
bool xlocked = false;
memset(&state, 0, sizeof(GISTInsertState));
state.freespace = freespace;
state.r = r;
/* Start from the root */
firststack.blkno = GIST_ROOT_BLKNO;
firststack.lsn = 0;
firststack.parent = NULL;
firststack.downlinkoffnum = InvalidOffsetNumber;
state.stack = stack = &firststack;
/*
* Walk down along the path of smallest penalty, updating the parent
* pointers with the key we're inserting as we go. If we crash in the
* middle, the tree is consistent, although the possible parent updates
* were a waste.
*/
for (;;)
{
if (XLogRecPtrIsInvalid(stack->lsn))
stack->buffer = ReadBuffer(state.r, stack->blkno);
/*
* Be optimistic and grab shared lock first. Swap it for an exclusive
* lock later if we need to update the page.
*/
if (!xlocked)
{
LockBuffer(stack->buffer, GIST_SHARE);
gistcheckpage(state.r, stack->buffer);
}
stack->page = (Page) BufferGetPage(stack->buffer);
stack->lsn = PageGetLSN(stack->page);
Assert(!RelationNeedsWAL(state.r) || !XLogRecPtrIsInvalid(stack->lsn));
/*
* If this page was split but the downlink was never inserted to the
* parent because the inserting backend crashed before doing that, fix
* that now.
*/
if (GistFollowRight(stack->page))
{
if (!xlocked)
{
LockBuffer(stack->buffer, GIST_UNLOCK);
LockBuffer(stack->buffer, GIST_EXCLUSIVE);
xlocked = true;
/* someone might've completed the split when we unlocked */
if (!GistFollowRight(stack->page))
continue;
}
gistfixsplit(&state, giststate);
UnlockReleaseBuffer(stack->buffer);
xlocked = false;
state.stack = stack = stack->parent;
continue;
}
if (stack->blkno != GIST_ROOT_BLKNO &&
stack->parent->lsn < GistPageGetNSN(stack->page))
{
/*
* Concurrent split detected. There's no guarantee that the
* downlink for this page is consistent with the tuple we're
* inserting anymore, so go back to parent and rechoose the best
* child.
*/
UnlockReleaseBuffer(stack->buffer);
xlocked = false;
state.stack = stack = stack->parent;
continue;
}
if (!GistPageIsLeaf(stack->page))
{
/*
* This is an internal page so continue to walk down the tree.
* Find the child node that has the minimum insertion penalty.
*/
BlockNumber childblkno;
IndexTuple newtup;
GISTInsertStack *item;
OffsetNumber downlinkoffnum;
downlinkoffnum = gistchoose(state.r, stack->page, itup, giststate);
iid = PageGetItemId(stack->page, downlinkoffnum);
idxtuple = (IndexTuple) PageGetItem(stack->page, iid);
childblkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
/*
* Check that it's not a leftover invalid tuple from pre-9.1
*/
if (GistTupleIsInvalid(idxtuple))
ereport(ERROR,
(errmsg("index \"%s\" contains an inner tuple marked as invalid",
RelationGetRelationName(r)),
errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
errhint("Please REINDEX it.")));
/*
* Check that the key representing the target child node is
* consistent with the key we're inserting. Update it if it's not.
*/
newtup = gistgetadjusted(state.r, idxtuple, itup, giststate);
if (newtup)
{
/*
* Swap shared lock for an exclusive one. Beware, the page may
* change while we unlock/lock the page...
*/
if (!xlocked)
{
LockBuffer(stack->buffer, GIST_UNLOCK);
LockBuffer(stack->buffer, GIST_EXCLUSIVE);
xlocked = true;
stack->page = (Page) BufferGetPage(stack->buffer);
if (PageGetLSN(stack->page) != stack->lsn)
{
/* the page was changed while we unlocked it, retry */
continue;
}
}
/*
* Update the tuple.
*
* We still hold the lock after gistinserttuple(), but it
* might have to split the page to make the updated tuple fit.
* In that case the updated tuple might migrate to the other
* half of the split, so we have to go back to the parent and
* descend back to the half that's a better fit for the new
* tuple.
*/
if (gistinserttuple(&state, stack, giststate, newtup,
downlinkoffnum))
{
/*
* If this was a root split, the root page continues to be
* the parent and the updated tuple went to one of the
* child pages, so we just need to retry from the root
* page.
*/
if (stack->blkno != GIST_ROOT_BLKNO)
{
UnlockReleaseBuffer(stack->buffer);
xlocked = false;
state.stack = stack = stack->parent;
}
continue;
}
}
LockBuffer(stack->buffer, GIST_UNLOCK);
xlocked = false;
/* descend to the chosen child */
item = (GISTInsertStack *) palloc0(sizeof(GISTInsertStack));
item->blkno = childblkno;
item->parent = stack;
item->downlinkoffnum = downlinkoffnum;
state.stack = stack = item;
}
else
{
/*
* Leaf page. Insert the new key. We've already updated all the
* parents on the way down, but we might have to split the page if
* it doesn't fit. gistinserthere() will take care of that.
*/
/*
* Swap shared lock for an exclusive one. Be careful, the page may
* change while we unlock/lock the page...
*/
if (!xlocked)
{
LockBuffer(stack->buffer, GIST_UNLOCK);
LockBuffer(stack->buffer, GIST_EXCLUSIVE);
xlocked = true;
stack->page = (Page) BufferGetPage(stack->buffer);
stack->lsn = PageGetLSN(stack->page);
if (stack->blkno == GIST_ROOT_BLKNO)
{
/*
* the only page that can become inner instead of leaf is
* the root page, so for root we should recheck it
*/
if (!GistPageIsLeaf(stack->page))
{
/*
* very rare situation: during unlock/lock index with
* number of pages = 1 was increased
*/
LockBuffer(stack->buffer, GIST_UNLOCK);
xlocked = false;
continue;
}
/*
* we don't need to check root split, because checking
* leaf/inner is enough to recognize split for root
*/
}
else if (GistFollowRight(stack->page) ||
stack->parent->lsn < GistPageGetNSN(stack->page))
{
/*
* The page was split while we momentarily unlocked the
* page. Go back to parent.
*/
UnlockReleaseBuffer(stack->buffer);
xlocked = false;
state.stack = stack = stack->parent;
continue;
}
}
/* now state.stack->(page, buffer and blkno) points to leaf page */
gistinserttuple(&state, stack, giststate, itup,
InvalidOffsetNumber);
LockBuffer(stack->buffer, GIST_UNLOCK);
/* Release any pins we might still hold before exiting */
for (; stack; stack = stack->parent)
ReleaseBuffer(stack->buffer);
break;
}
}
}
/*
* returns modified page or NULL if page isn't modified.
* Function works with original page until first change is occurred,
* then page is copied into temporary one.
*/
static Page
ginVacuumEntryPage(GinVacuumState *gvs, Buffer buffer, BlockNumber *roots, uint32 *nroot)
{
Page origpage = BufferGetPage(buffer),
tmppage;
OffsetNumber i,
maxoff = PageGetMaxOffsetNumber(origpage);
tmppage = origpage;
*nroot = 0;
for (i = FirstOffsetNumber; i <= maxoff; i++)
{
IndexTuple itup = (IndexTuple) PageGetItem(tmppage, PageGetItemId(tmppage, i));
if (GinIsPostingTree(itup))
{
/*
* store posting tree's roots for further processing, we can't
* vacuum it just now due to risk of deadlocks with scans/inserts
*/
roots[*nroot] = GinGetDownlink(itup);
(*nroot)++;
}
else if (GinGetNPosting(itup) > 0)
{
int nitems;
ItemPointer uncompressed;
/*
* Vacuum posting list with proper function for compressed and
* uncompressed format.
*/
if (GinItupIsCompressed(itup))
uncompressed = ginPostingListDecode((GinPostingList *) GinGetPosting(itup), &nitems);
else
{
uncompressed = (ItemPointer) GinGetPosting(itup);
nitems = GinGetNPosting(itup);
}
uncompressed = ginVacuumItemPointers(gvs, uncompressed, nitems,
&nitems);
if (uncompressed)
{
/*
* Some ItemPointers were deleted, recreate tuple.
*/
OffsetNumber attnum;
Datum key;
GinNullCategory category;
GinPostingList *plist;
int plistsize;
if (nitems > 0)
{
plist = ginCompressPostingList(uncompressed, nitems, GinMaxItemSize, NULL);
plistsize = SizeOfGinPostingList(plist);
}
else
{
plist = NULL;
plistsize = 0;
}
/*
* if we already created a temporary page, make changes in place
*/
if (tmppage == origpage)
{
/*
* On first difference, create a temporary copy of the
* page and copy the tuple's posting list to it.
*/
tmppage = PageGetTempPageCopy(origpage);
/* set itup pointer to new page */
itup = (IndexTuple) PageGetItem(tmppage, PageGetItemId(tmppage, i));
}
attnum = gintuple_get_attrnum(&gvs->ginstate, itup);
key = gintuple_get_key(&gvs->ginstate, itup, &category);
itup = GinFormTuple(&gvs->ginstate, attnum, key, category,
(char *) plist, plistsize,
nitems, true);
if (plist)
pfree(plist);
PageIndexTupleDelete(tmppage, i);
if (PageAddItem(tmppage, (Item) itup, IndexTupleSize(itup), i, false, false) != i)
elog(ERROR, "failed to add item to index page in \"%s\"",
RelationGetRelationName(gvs->index));
pfree(itup);
}
}
}
return (tmppage == origpage) ? NULL : tmppage;
}
/*
* Updates the stack so that child->parent is the correct parent of the
* child. child->parent must be exclusively locked on entry, and will
* remain so at exit, but it might not be the same page anymore.
*/
static void
gistFindCorrectParent(Relation r, GISTInsertStack *child)
{
GISTInsertStack *parent = child->parent;
gistcheckpage(r, parent->buffer);
parent->page = (Page) BufferGetPage(parent->buffer);
/* here we don't need to distinguish between split and page update */
if (child->downlinkoffnum == InvalidOffsetNumber ||
parent->lsn != PageGetLSN(parent->page))
{
/* parent is changed, look child in right links until found */
OffsetNumber i,
maxoff;
ItemId iid;
IndexTuple idxtuple;
GISTInsertStack *ptr;
while (true)
{
maxoff = PageGetMaxOffsetNumber(parent->page);
for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
{
iid = PageGetItemId(parent->page, i);
idxtuple = (IndexTuple) PageGetItem(parent->page, iid);
if (ItemPointerGetBlockNumber(&(idxtuple->t_tid)) == child->blkno)
{
/* yes!!, found */
child->downlinkoffnum = i;
return;
}
}
parent->blkno = GistPageGetOpaque(parent->page)->rightlink;
UnlockReleaseBuffer(parent->buffer);
if (parent->blkno == InvalidBlockNumber)
{
/*
* End of chain and still didn't find parent. It's a very-very
* rare situation when root splited.
*/
break;
}
parent->buffer = ReadBuffer(r, parent->blkno);
LockBuffer(parent->buffer, GIST_EXCLUSIVE);
gistcheckpage(r, parent->buffer);
parent->page = (Page) BufferGetPage(parent->buffer);
}
/*
* awful!!, we need search tree to find parent ... , but before we
* should release all old parent
*/
ptr = child->parent->parent; /* child->parent already released
* above */
while (ptr)
{
ReleaseBuffer(ptr->buffer);
ptr = ptr->parent;
}
/* ok, find new path */
ptr = parent = gistFindPath(r, child->blkno, &child->downlinkoffnum);
/* read all buffers as expected by caller */
/* note we don't lock them or gistcheckpage them here! */
while (ptr)
{
ptr->buffer = ReadBuffer(r, ptr->blkno);
ptr->page = (Page) BufferGetPage(ptr->buffer);
ptr = ptr->parent;
}
/* install new chain of parents to stack */
child->parent = parent;
/* make recursive call to normal processing */
LockBuffer(child->parent->buffer, GIST_EXCLUSIVE);
gistFindCorrectParent(r, child);
}
return;
}
Datum
ginbulkdelete(PG_FUNCTION_ARGS)
{
IndexVacuumInfo *info = (IndexVacuumInfo *) PG_GETARG_POINTER(0);
IndexBulkDeleteResult *stats = (IndexBulkDeleteResult *) PG_GETARG_POINTER(1);
IndexBulkDeleteCallback callback = (IndexBulkDeleteCallback) PG_GETARG_POINTER(2);
void *callback_state = (void *) PG_GETARG_POINTER(3);
Relation index = info->index;
BlockNumber blkno = GIN_ROOT_BLKNO;
GinVacuumState gvs;
Buffer buffer;
BlockNumber rootOfPostingTree[BLCKSZ / (sizeof(IndexTupleData) + sizeof(ItemId))];
uint32 nRoot;
gvs.tmpCxt = AllocSetContextCreate(CurrentMemoryContext,
"Gin vacuum temporary context",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
gvs.index = index;
gvs.callback = callback;
gvs.callback_state = callback_state;
gvs.strategy = info->strategy;
initGinState(&gvs.ginstate, index);
/* first time through? */
if (stats == NULL)
{
/* Yes, so initialize stats to zeroes */
stats = (IndexBulkDeleteResult *) palloc0(sizeof(IndexBulkDeleteResult));
/* and cleanup any pending inserts */
ginInsertCleanup(&gvs.ginstate, true, stats);
}
/* we'll re-count the tuples each time */
stats->num_index_tuples = 0;
gvs.result = stats;
buffer = ReadBufferExtended(index, MAIN_FORKNUM, blkno,
RBM_NORMAL, info->strategy);
/* find leaf page */
for (;;)
{
Page page = BufferGetPage(buffer);
IndexTuple itup;
LockBuffer(buffer, GIN_SHARE);
Assert(!GinPageIsData(page));
if (GinPageIsLeaf(page))
{
LockBuffer(buffer, GIN_UNLOCK);
LockBuffer(buffer, GIN_EXCLUSIVE);
if (blkno == GIN_ROOT_BLKNO && !GinPageIsLeaf(page))
{
LockBuffer(buffer, GIN_UNLOCK);
continue; /* check it one more */
}
break;
}
Assert(PageGetMaxOffsetNumber(page) >= FirstOffsetNumber);
itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, FirstOffsetNumber));
blkno = GinGetDownlink(itup);
Assert(blkno != InvalidBlockNumber);
UnlockReleaseBuffer(buffer);
buffer = ReadBufferExtended(index, MAIN_FORKNUM, blkno,
RBM_NORMAL, info->strategy);
}
/* right now we found leftmost page in entry's BTree */
for (;;)
{
Page page = BufferGetPage(buffer);
Page resPage;
uint32 i;
Assert(!GinPageIsData(page));
resPage = ginVacuumEntryPage(&gvs, buffer, rootOfPostingTree, &nRoot);
blkno = GinPageGetOpaque(page)->rightlink;
if (resPage)
{
START_CRIT_SECTION();
PageRestoreTempPage(resPage, page);
MarkBufferDirty(buffer);
xlogVacuumPage(gvs.index, buffer);
UnlockReleaseBuffer(buffer);
END_CRIT_SECTION();
}
else
{
UnlockReleaseBuffer(buffer);
}
vacuum_delay_point();
for (i = 0; i < nRoot; i++)
{
ginVacuumPostingTree(&gvs, rootOfPostingTree[i]);
vacuum_delay_point();
}
if (blkno == InvalidBlockNumber) /* rightmost page */
break;
buffer = ReadBufferExtended(index, MAIN_FORKNUM, blkno,
RBM_NORMAL, info->strategy);
LockBuffer(buffer, GIN_EXCLUSIVE);
}
MemoryContextDelete(gvs.tmpCxt);
PG_RETURN_POINTER(gvs.result);
}
/*
* _hash_squeezebucket(rel, bucket)
*
* Try to squeeze the tuples onto pages occurring earlier in the
* bucket chain in an attempt to free overflow pages. When we start
* the "squeezing", the page from which we start taking tuples (the
* "read" page) is the last bucket in the bucket chain and the page
* onto which we start squeezing tuples (the "write" page) is the
* first page in the bucket chain. The read page works backward and
* the write page works forward; the procedure terminates when the
* read page and write page are the same page.
*
* At completion of this procedure, it is guaranteed that all pages in
* the bucket are nonempty, unless the bucket is totally empty (in
* which case all overflow pages will be freed). The original implementation
* required that to be true on entry as well, but it's a lot easier for
* callers to leave empty overflow pages and let this guy clean it up.
*
* Caller must hold exclusive lock on the target bucket. This allows
* us to safely lock multiple pages in the bucket.
*
* Since this function is invoked in VACUUM, we provide an access strategy
* parameter that controls fetches of the bucket pages.
*/
void
_hash_squeezebucket(Relation rel,
Bucket bucket,
BlockNumber bucket_blkno,
BufferAccessStrategy bstrategy)
{
BlockNumber wblkno;
BlockNumber rblkno;
Buffer wbuf;
Buffer rbuf;
Page wpage;
Page rpage;
HashPageOpaque wopaque;
HashPageOpaque ropaque;
bool wbuf_dirty;
/*
* start squeezing into the base bucket page.
*/
wblkno = bucket_blkno;
wbuf = _hash_getbuf_with_strategy(rel,
wblkno,
HASH_WRITE,
LH_BUCKET_PAGE,
bstrategy);
wpage = BufferGetPage(wbuf);
wopaque = (HashPageOpaque) PageGetSpecialPointer(wpage);
/*
* if there aren't any overflow pages, there's nothing to squeeze.
*/
if (!BlockNumberIsValid(wopaque->hasho_nextblkno))
{
_hash_relbuf(rel, wbuf);
return;
}
/*
* Find the last page in the bucket chain by starting at the base bucket
* page and working forward. Note: we assume that a hash bucket chain is
* usually smaller than the buffer ring being used by VACUUM, else using
* the access strategy here would be counterproductive.
*/
rbuf = InvalidBuffer;
ropaque = wopaque;
do
{
rblkno = ropaque->hasho_nextblkno;
if (rbuf != InvalidBuffer)
_hash_relbuf(rel, rbuf);
rbuf = _hash_getbuf_with_strategy(rel,
rblkno,
HASH_WRITE,
LH_OVERFLOW_PAGE,
bstrategy);
rpage = BufferGetPage(rbuf);
ropaque = (HashPageOpaque) PageGetSpecialPointer(rpage);
Assert(ropaque->hasho_bucket == bucket);
} while (BlockNumberIsValid(ropaque->hasho_nextblkno));
/*
* squeeze the tuples.
*/
wbuf_dirty = false;
for (;;)
{
OffsetNumber roffnum;
OffsetNumber maxroffnum;
OffsetNumber deletable[MaxOffsetNumber];
int ndeletable = 0;
/* Scan each tuple in "read" page */
maxroffnum = PageGetMaxOffsetNumber(rpage);
for (roffnum = FirstOffsetNumber;
roffnum <= maxroffnum;
roffnum = OffsetNumberNext(roffnum))
{
IndexTuple itup;
Size itemsz;
itup = (IndexTuple) PageGetItem(rpage,
PageGetItemId(rpage, roffnum));
itemsz = IndexTupleDSize(*itup);
itemsz = MAXALIGN(itemsz);
/*
* Walk up the bucket chain, looking for a page big enough for
* this item. Exit if we reach the read page.
*/
while (PageGetFreeSpace(wpage) < itemsz)
{
Assert(!PageIsEmpty(wpage));
wblkno = wopaque->hasho_nextblkno;
Assert(BlockNumberIsValid(wblkno));
if (wbuf_dirty)
_hash_wrtbuf(rel, wbuf);
else
_hash_relbuf(rel, wbuf);
/* nothing more to do if we reached the read page */
if (rblkno == wblkno)
{
if (ndeletable > 0)
{
/* Delete tuples we already moved off read page */
PageIndexMultiDelete(rpage, deletable, ndeletable);
_hash_wrtbuf(rel, rbuf);
}
else
_hash_relbuf(rel, rbuf);
return;
}
wbuf = _hash_getbuf_with_strategy(rel,
wblkno,
HASH_WRITE,
LH_OVERFLOW_PAGE,
bstrategy);
wpage = BufferGetPage(wbuf);
wopaque = (HashPageOpaque) PageGetSpecialPointer(wpage);
Assert(wopaque->hasho_bucket == bucket);
wbuf_dirty = false;
}
/*
* we have found room so insert on the "write" page, being careful
* to preserve hashkey ordering. (If we insert many tuples into
* the same "write" page it would be worth qsort'ing instead of
* doing repeated _hash_pgaddtup.)
*/
(void) _hash_pgaddtup(rel, wbuf, itemsz, itup);
wbuf_dirty = true;
/* remember tuple for deletion from "read" page */
deletable[ndeletable++] = roffnum;
}
/*
* If we reach here, there are no live tuples on the "read" page ---
* it was empty when we got to it, or we moved them all. So we can
* just free the page without bothering with deleting tuples
* individually. Then advance to the previous "read" page.
*
* Tricky point here: if our read and write pages are adjacent in the
* bucket chain, our write lock on wbuf will conflict with
* _hash_freeovflpage's attempt to update the sibling links of the
* removed page. However, in that case we are done anyway, so we can
* simply drop the write lock before calling _hash_freeovflpage.
*/
rblkno = ropaque->hasho_prevblkno;
Assert(BlockNumberIsValid(rblkno));
/* are we freeing the page adjacent to wbuf? */
if (rblkno == wblkno)
{
/* yes, so release wbuf lock first */
if (wbuf_dirty)
_hash_wrtbuf(rel, wbuf);
else
_hash_relbuf(rel, wbuf);
/* free this overflow page (releases rbuf) */
_hash_freeovflpage(rel, rbuf, bstrategy);
/* done */
return;
}
/* free this overflow page, then get the previous one */
_hash_freeovflpage(rel, rbuf, bstrategy);
rbuf = _hash_getbuf_with_strategy(rel,
rblkno,
HASH_WRITE,
LH_OVERFLOW_PAGE,
bstrategy);
rpage = BufferGetPage(rbuf);
ropaque = (HashPageOpaque) PageGetSpecialPointer(rpage);
Assert(ropaque->hasho_bucket == bucket);
}
/* NOTREACHED */
}
/*
* Insert a tuple to the new relation. This has to track heap_insert
* and its subsidiary functions!
*
* t_self of the tuple is set to the new TID of the tuple. If t_ctid of the
* tuple is invalid on entry, it's replaced with the new TID as well (in
* the inserted data only, not in the caller's copy).
*/
static void
raw_heap_insert(RewriteState state, HeapTuple tup)
{
Page page = state->rs_buffer;
Size pageFreeSpace,
saveFreeSpace;
Size len;
OffsetNumber newoff;
HeapTuple heaptup;
/*
* If the new tuple is too big for storage or contains already toasted
* out-of-line attributes from some other relation, invoke the toaster.
*
* Note: below this point, heaptup is the data we actually intend to store
* into the relation; tup is the caller's original untoasted data.
*/
if (state->rs_new_rel->rd_rel->relkind == RELKIND_TOASTVALUE)
{
/* toast table entries should never be recursively toasted */
Assert(!HeapTupleHasExternal(tup));
heaptup = tup;
}
else if (HeapTupleHasExternal(tup) || tup->t_len > TOAST_TUPLE_THRESHOLD)
heaptup = toast_insert_or_update(state->rs_new_rel, tup, NULL, NULL,
TOAST_TUPLE_TARGET, false,
state->rs_use_wal, false);
else
heaptup = tup;
len = MAXALIGN(heaptup->t_len); /* be conservative */
/*
* If we're gonna fail for oversize tuple, do it right away
*/
if (len > MaxHeapTupleSize)
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("row is too big: size %lu, maximum size %lu",
(unsigned long) len,
(unsigned long) MaxHeapTupleSize)));
/* Compute desired extra freespace due to fillfactor option */
saveFreeSpace = RelationGetTargetPageFreeSpace(state->rs_new_rel,
HEAP_DEFAULT_FILLFACTOR);
/* Now we can check to see if there's enough free space already. */
if (state->rs_buffer_valid)
{
pageFreeSpace = PageGetHeapFreeSpace(page);
if (len + saveFreeSpace > pageFreeSpace)
{
/* Doesn't fit, so write out the existing page */
/* XLOG stuff */
if (state->rs_use_wal)
log_newpage(&state->rs_new_rel->rd_node,
state->rs_blockno,
page);
/*
* Now write the page. We say isTemp = true even if it's not a
* temp table, because there's no need for smgr to schedule an
* fsync for this write; we'll do it ourselves in
* end_heap_rewrite.
*/
RelationOpenSmgr(state->rs_new_rel);
smgrextend(state->rs_new_rel->rd_smgr, state->rs_blockno,
(char *) page, true);
state->rs_blockno++;
state->rs_buffer_valid = false;
}
}
if (!state->rs_buffer_valid)
{
/* Initialize a new empty page */
PageInit(page, BLCKSZ, 0);
state->rs_buffer_valid = true;
}
/* And now we can insert the tuple into the page */
newoff = PageAddItem(page, (Item) heaptup->t_data, heaptup->t_len,
InvalidOffsetNumber, false, true);
if (newoff == InvalidOffsetNumber)
elog(ERROR, "failed to add tuple");
/* Update caller's t_self to the actual position where it was stored */
ItemPointerSet(&(tup->t_self), state->rs_blockno, newoff);
/*
* Insert the correct position into CTID of the stored tuple, too, if the
* caller didn't supply a valid CTID.
*/
if (!ItemPointerIsValid(&tup->t_data->t_ctid))
{
ItemId newitemid;
HeapTupleHeader onpage_tup;
newitemid = PageGetItemId(page, newoff);
onpage_tup = (HeapTupleHeader) PageGetItem(page, newitemid);
onpage_tup->t_ctid = tup->t_self;
}
/* If heaptup is a private copy, release it. */
if (heaptup != tup)
heap_freetuple(heaptup);
}