/*
* Initiate page evacuation protocol.
*
* The page must be locked in exclusive mode by the caller.
*
* If the page is not yet initialized or empty, return false without doing
* anything; it can be used for revmap without any further changes. If it
* contains tuples, mark it for evacuation and return true.
*/
bool
brin_start_evacuating_page(Relation idxRel, Buffer buf)
{
OffsetNumber off;
OffsetNumber maxoff;
Page page;
page = BufferGetPage(buf);
if (PageIsNew(page))
return false;
maxoff = PageGetMaxOffsetNumber(page);
for (off = FirstOffsetNumber; off <= maxoff; off++)
{
ItemId lp;
lp = PageGetItemId(page, off);
if (ItemIdIsUsed(lp))
{
/* prevent other backends from adding more stuff to this page */
BrinPageFlags(page) |= BRIN_EVACUATE_PAGE;
MarkBufferDirtyHint(buf, true);
return true;
}
}
return false;
}
/*
* MUST BE CALLED ONLY ON RECOVERY.
*
* Check if exists valid (inserted by not aborted xaction) heap tuple
* for given item pointer
*/
bool
XLogIsValidTuple(RelFileNode hnode, ItemPointer iptr)
{
Relation reln;
Buffer buffer;
Page page;
ItemId lp;
HeapTupleHeader htup;
reln = XLogOpenRelation(false, RM_HEAP_ID, hnode);
if (!RelationIsValid(reln))
return (false);
buffer = ReadBuffer(reln, ItemPointerGetBlockNumber(iptr));
if (!BufferIsValid(buffer))
return (false);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
page = (Page) BufferGetPage(buffer);
if (PageIsNew((PageHeader) page) ||
ItemPointerGetOffsetNumber(iptr) > PageGetMaxOffsetNumber(page))
{
UnlockAndReleaseBuffer(buffer);
return (false);
}
if (PageGetSUI(page) != ThisStartUpID)
{
Assert(PageGetSUI(page) < ThisStartUpID);
UnlockAndReleaseBuffer(buffer);
return (true);
}
lp = PageGetItemId(page, ItemPointerGetOffsetNumber(iptr));
if (!ItemIdIsUsed(lp) || ItemIdDeleted(lp))
{
UnlockAndReleaseBuffer(buffer);
return (false);
}
htup = (HeapTupleHeader) PageGetItem(page, lp);
/* MUST CHECK WASN'T TUPLE INSERTED IN PREV STARTUP */
if (!(htup->t_infomask & HEAP_XMIN_COMMITTED))
{
if (htup->t_infomask & HEAP_XMIN_INVALID ||
(htup->t_infomask & HEAP_MOVED_IN &&
TransactionIdDidAbort(HeapTupleHeaderGetXvac(htup))) ||
TransactionIdDidAbort(HeapTupleHeaderGetXmin(htup)))
{
UnlockAndReleaseBuffer(buffer);
return (false);
}
}
UnlockAndReleaseBuffer(buffer);
return (true);
}
/*
* PageGetHeapFreeSpace
* Returns the size of the free (allocatable) space on a page,
* reduced by the space needed for a new line pointer.
*
* The difference between this and PageGetFreeSpace is that this will return
* zero if there are already MaxHeapTuplesPerPage line pointers in the page
* and none are free. We use this to enforce that no more than
* MaxHeapTuplesPerPage line pointers are created on a heap page. (Although
* no more tuples than that could fit anyway, in the presence of redirected
* or dead line pointers it'd be possible to have too many line pointers.
* To avoid breaking code that assumes MaxHeapTuplesPerPage is a hard limit
* on the number of line pointers, we make this extra check.)
*/
Size
PageGetHeapFreeSpace(Page page)
{
Size space;
space = PageGetFreeSpace(page);
if (space > 0)
{
OffsetNumber offnum,
nline;
/*
* Are there already MaxHeapTuplesPerPage line pointers in the page?
*/
nline = PageGetMaxOffsetNumber(page);
if (nline >= MaxHeapTuplesPerPage)
{
if (PageHasFreeLinePointers((PageHeader) page))
{
/*
* Since this is just a hint, we must confirm that there is
* indeed a free line pointer
*/
for (offnum = FirstOffsetNumber; offnum <= nline; offnum = OffsetNumberNext(offnum))
{
ItemId lp = PageGetItemId(page, offnum);
if (!ItemIdIsUsed(lp))
break;
}
if (offnum > nline)
{
/*
* The hint is wrong, but we can't clear it here since we
* don't have the ability to mark the page dirty.
*/
space = 0;
}
}
else
{
/*
* Although the hint might be wrong, PageAddItem will believe
* it anyway, so we must believe it too.
*/
space = 0;
}
}
}
return space;
}
/*
* Check if specified heap tuple was inserted by given
* xaction/command and return
*
* - -1 if not
* - 0 if there is no tuple at all
* - 1 if yes
*/
int
XLogIsOwnerOfTuple(RelFileNode hnode, ItemPointer iptr,
TransactionId xid, CommandId cid)
{
Relation reln;
Buffer buffer;
Page page;
ItemId lp;
HeapTupleHeader htup;
reln = XLogOpenRelation(false, RM_HEAP_ID, hnode);
if (!RelationIsValid(reln))
return (0);
buffer = ReadBuffer(reln, ItemPointerGetBlockNumber(iptr));
if (!BufferIsValid(buffer))
return (0);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
page = (Page) BufferGetPage(buffer);
if (PageIsNew((PageHeader) page) ||
ItemPointerGetOffsetNumber(iptr) > PageGetMaxOffsetNumber(page))
{
UnlockAndReleaseBuffer(buffer);
return (0);
}
lp = PageGetItemId(page, ItemPointerGetOffsetNumber(iptr));
if (!ItemIdIsUsed(lp) || ItemIdDeleted(lp))
{
UnlockAndReleaseBuffer(buffer);
return (0);
}
htup = (HeapTupleHeader) PageGetItem(page, lp);
Assert(PageGetSUI(page) == ThisStartUpID);
if (!TransactionIdEquals(HeapTupleHeaderGetXmin(htup), xid) ||
HeapTupleHeaderGetCmin(htup) != cid)
{
UnlockAndReleaseBuffer(buffer);
return (-1);
}
UnlockAndReleaseBuffer(buffer);
return (1);
}
/*
* mask_lp_flags
*
* In some index AMs, line pointer flags can be modified in master without
* emitting any WAL record.
*/
void
mask_lp_flags(Page page)
{
OffsetNumber offnum,
maxoff;
maxoff = PageGetMaxOffsetNumber(page);
for (offnum = FirstOffsetNumber;
offnum <= maxoff;
offnum = OffsetNumberNext(offnum))
{
ItemId itemId = PageGetItemId(page, offnum);
if (ItemIdIsUsed(itemId))
itemId->lp_flags = LP_UNUSED;
}
}
/*
* Move all tuples out of a page.
*
* The caller must hold lock on the page. The lock and pin are released.
*/
void
brin_evacuate_page(Relation idxRel, BlockNumber pagesPerRange,
BrinRevmap *revmap, Buffer buf)
{
OffsetNumber off;
OffsetNumber maxoff;
Page page;
page = BufferGetPage(buf);
Assert(((BrinSpecialSpace *)
PageGetSpecialPointer(page))->flags & BRIN_EVACUATE_PAGE);
maxoff = PageGetMaxOffsetNumber(page);
for (off = FirstOffsetNumber; off <= maxoff; off++)
{
BrinTuple *tup;
Size sz;
ItemId lp;
CHECK_FOR_INTERRUPTS();
lp = PageGetItemId(page, off);
if (ItemIdIsUsed(lp))
{
sz = ItemIdGetLength(lp);
tup = (BrinTuple *) PageGetItem(page, lp);
tup = brin_copy_tuple(tup, sz);
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
if (!brin_doupdate(idxRel, pagesPerRange, revmap, tup->bt_blkno,
buf, off, tup, sz, tup, sz, false))
off--; /* retry */
LockBuffer(buf, BUFFER_LOCK_SHARE);
/* It's possible that someone extended the revmap over this page */
if (!BRIN_IS_REGULAR_PAGE(page))
break;
}
}
UnlockReleaseBuffer(buf);
}
/*
* PageAddItemExtended
*
* Add an item to a page. Return value is the offset at which it was
* inserted, or InvalidOffsetNumber if the item is not inserted for any
* reason. A WARNING is issued indicating the reason for the refusal.
*
* offsetNumber must be either InvalidOffsetNumber to specify finding a
* free item pointer, or a value between FirstOffsetNumber and one past
* the last existing item, to specify using that particular item pointer.
*
* If offsetNumber is valid and flag PAI_OVERWRITE is set, 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.
*
* If offsetNumber is valid and flag PAI_OVERWRITE is not set, insert
* the item at the specified offsetNumber, moving existing items later
* in the array to make room.
*
* If offsetNumber is not valid, then assign a slot by finding the first
* one that is both unused and deallocated.
*
* If flag PAI_IS_HEAP is set, we enforce that there can't be more than
* MaxHeapTuplesPerPage line pointers on the page.
*
* !!! EREPORT(ERROR) IS DISALLOWED HERE !!!
*/
OffsetNumber
PageAddItemExtended(Page page,
Item item,
Size size,
OffsetNumber offsetNumber,
int flags)
{
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 ((flags & PAI_OVERWRITE) != 0)
{
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;
}
}
/* Reject placing items beyond the first unused line pointer */
if (offsetNumber > limit)
{
elog(WARNING, "specified item offset is too large");
return InvalidOffsetNumber;
}
/* Reject placing items beyond heap boundary, if heap */
if ((flags & PAI_IS_HEAP) != 0 && 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);
/*
* Items normally contain no uninitialized bytes. Core bufpage consumers
* conform, but this is not a necessary coding rule; a new index AM could
* opt to depart from it. However, data type input functions and other
* C-language functions that synthesize datums should initialize all
* bytes; datumIsEqual() relies on this. Testing here, along with the
* similar check in printtup(), helps to catch such mistakes.
*
* Values of the "name" type retrieved via index-only scans may contain
* uninitialized bytes; see comment in btrescan(). Valgrind will report
* this as an error, but it is safe to ignore.
*/
VALGRIND_CHECK_MEM_IS_DEFINED(item, 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;
}
/*
* This function takes an already open relation and scans its pages,
* skipping those that have the corresponding visibility map bit set.
* For pages we skip, we find the free space from the free space map
* and approximate tuple_len on that basis. For the others, we count
* the exact number of dead tuples etc.
*
* This scan is loosely based on vacuumlazy.c:lazy_scan_heap(), but
* we do not try to avoid skipping single pages.
*/
static void
statapprox_heap(Relation rel, output_type *stat)
{
BlockNumber scanned,
nblocks,
blkno;
Buffer vmbuffer = InvalidBuffer;
BufferAccessStrategy bstrategy;
TransactionId OldestXmin;
uint64 misc_count = 0;
OldestXmin = GetOldestXmin(rel, PROCARRAY_FLAGS_VACUUM);
bstrategy = GetAccessStrategy(BAS_BULKREAD);
nblocks = RelationGetNumberOfBlocks(rel);
scanned = 0;
for (blkno = 0; blkno < nblocks; blkno++)
{
Buffer buf;
Page page;
OffsetNumber offnum,
maxoff;
Size freespace;
CHECK_FOR_INTERRUPTS();
/*
* If the page has only visible tuples, then we can find out the free
* space from the FSM and move on.
*/
if (VM_ALL_VISIBLE(rel, blkno, &vmbuffer))
{
freespace = GetRecordedFreeSpace(rel, blkno);
stat->tuple_len += BLCKSZ - freespace;
stat->free_space += freespace;
continue;
}
buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno,
RBM_NORMAL, bstrategy);
LockBuffer(buf, BUFFER_LOCK_SHARE);
page = BufferGetPage(buf);
/*
* It's not safe to call PageGetHeapFreeSpace() on new pages, so we
* treat them as being free space for our purposes.
*/
if (!PageIsNew(page))
stat->free_space += PageGetHeapFreeSpace(page);
else
stat->free_space += BLCKSZ - SizeOfPageHeaderData;
if (PageIsNew(page) || PageIsEmpty(page))
{
UnlockReleaseBuffer(buf);
continue;
}
scanned++;
/*
* Look at each tuple on the page and decide whether it's live or
* dead, then count it and its size. Unlike lazy_scan_heap, we can
* afford to ignore problems and special cases.
*/
maxoff = PageGetMaxOffsetNumber(page);
for (offnum = FirstOffsetNumber;
offnum <= maxoff;
offnum = OffsetNumberNext(offnum))
{
ItemId itemid;
HeapTupleData tuple;
itemid = PageGetItemId(page, offnum);
if (!ItemIdIsUsed(itemid) || ItemIdIsRedirected(itemid) ||
ItemIdIsDead(itemid))
{
continue;
}
Assert(ItemIdIsNormal(itemid));
ItemPointerSet(&(tuple.t_self), blkno, offnum);
tuple.t_data = (HeapTupleHeader) PageGetItem(page, itemid);
tuple.t_len = ItemIdGetLength(itemid);
tuple.t_tableOid = RelationGetRelid(rel);
/*
* We count live and dead tuples, but we also need to add up
* others in order to feed vac_estimate_reltuples.
*/
switch (HeapTupleSatisfiesVacuum(&tuple, OldestXmin, buf))
{
case HEAPTUPLE_RECENTLY_DEAD:
misc_count++;
/* Fall through */
case HEAPTUPLE_DEAD:
stat->dead_tuple_len += tuple.t_len;
stat->dead_tuple_count++;
break;
case HEAPTUPLE_LIVE:
stat->tuple_len += tuple.t_len;
stat->tuple_count++;
break;
case HEAPTUPLE_INSERT_IN_PROGRESS:
case HEAPTUPLE_DELETE_IN_PROGRESS:
misc_count++;
break;
default:
elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result");
break;
}
}
UnlockReleaseBuffer(buf);
}
stat->table_len = (uint64) nblocks *BLCKSZ;
stat->tuple_count = vac_estimate_reltuples(rel, false, nblocks, scanned,
stat->tuple_count + misc_count);
/*
* Calculate percentages if the relation has one or more pages.
*/
if (nblocks != 0)
{
stat->scanned_percent = 100 * scanned / nblocks;
stat->tuple_percent = 100.0 * stat->tuple_len / stat->table_len;
stat->dead_tuple_percent = 100.0 * stat->dead_tuple_len / stat->table_len;
stat->free_percent = 100.0 * stat->free_space / stat->table_len;
}
if (BufferIsValid(vmbuffer))
{
ReleaseBuffer(vmbuffer);
vmbuffer = InvalidBuffer;
}
}
/*
* Fetch the BrinTuple for a given heap block.
*
* The buffer containing the tuple is locked, and returned in *buf. As an
* optimization, the caller can pass a pinned buffer *buf on entry, which will
* avoid a pin-unpin cycle when the next tuple is on the same page as a
* previous one.
*
* If no tuple is found for the given heap range, returns NULL. In that case,
* *buf might still be updated, but it's not locked.
*
* The output tuple offset within the buffer is returned in *off, and its size
* is returned in *size.
*/
BrinTuple *
brinGetTupleForHeapBlock(BrinRevmap *revmap, BlockNumber heapBlk,
Buffer *buf, OffsetNumber *off, Size *size, int mode)
{
Relation idxRel = revmap->rm_irel;
BlockNumber mapBlk;
RevmapContents *contents;
ItemPointerData *iptr;
BlockNumber blk;
Page page;
ItemId lp;
BrinTuple *tup;
ItemPointerData previptr;
/* normalize the heap block number to be the first page in the range */
heapBlk = (heapBlk / revmap->rm_pagesPerRange) * revmap->rm_pagesPerRange;
/* Compute the revmap page number we need */
mapBlk = revmap_get_blkno(revmap, heapBlk);
if (mapBlk == InvalidBlockNumber)
{
*off = InvalidOffsetNumber;
return NULL;
}
ItemPointerSetInvalid(&previptr);
for (;;)
{
CHECK_FOR_INTERRUPTS();
if (revmap->rm_currBuf == InvalidBuffer ||
BufferGetBlockNumber(revmap->rm_currBuf) != mapBlk)
{
if (revmap->rm_currBuf != InvalidBuffer)
ReleaseBuffer(revmap->rm_currBuf);
Assert(mapBlk != InvalidBlockNumber);
revmap->rm_currBuf = ReadBuffer(revmap->rm_irel, mapBlk);
}
LockBuffer(revmap->rm_currBuf, BUFFER_LOCK_SHARE);
contents = (RevmapContents *)
PageGetContents(BufferGetPage(revmap->rm_currBuf));
iptr = contents->rm_tids;
iptr += HEAPBLK_TO_REVMAP_INDEX(revmap->rm_pagesPerRange, heapBlk);
if (!ItemPointerIsValid(iptr))
{
LockBuffer(revmap->rm_currBuf, BUFFER_LOCK_UNLOCK);
return NULL;
}
/*
* Check the TID we got in a previous iteration, if any, and save the
* current TID we got from the revmap; if we loop, we can sanity-check
* that the next one we get is different. Otherwise we might be stuck
* looping forever if the revmap is somehow badly broken.
*/
if (ItemPointerIsValid(&previptr) && ItemPointerEquals(&previptr, iptr))
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg_internal("corrupted BRIN index: inconsistent range map")));
previptr = *iptr;
blk = ItemPointerGetBlockNumber(iptr);
*off = ItemPointerGetOffsetNumber(iptr);
LockBuffer(revmap->rm_currBuf, BUFFER_LOCK_UNLOCK);
/* Ok, got a pointer to where the BrinTuple should be. Fetch it. */
if (!BufferIsValid(*buf) || BufferGetBlockNumber(*buf) != blk)
{
if (BufferIsValid(*buf))
ReleaseBuffer(*buf);
*buf = ReadBuffer(idxRel, blk);
}
LockBuffer(*buf, mode);
page = BufferGetPage(*buf);
/* If we land on a revmap page, start over */
if (BRIN_IS_REGULAR_PAGE(page))
{
lp = PageGetItemId(page, *off);
if (ItemIdIsUsed(lp))
{
tup = (BrinTuple *) PageGetItem(page, lp);
if (tup->bt_blkno == heapBlk)
{
if (size)
*size = ItemIdGetLength(lp);
/* found it! */
return tup;
}
}
}
/*
* No luck. Assume that the revmap was updated concurrently.
*/
LockBuffer(*buf, BUFFER_LOCK_UNLOCK);
}
/* not reached, but keep compiler quiet */
return NULL;
}
/*
* Get the latestRemovedXid from the heap pages pointed at by the index
* tuples being deleted. This puts the work for calculating latestRemovedXid
* into the recovery path rather than the primary path.
*
* It's possible that this generates a fair amount of I/O, since an index
* block may have hundreds of tuples being deleted. Repeat accesses to the
* same heap blocks are common, though are not yet optimised.
*
* XXX optimise later with something like XLogPrefetchBuffer()
*/
static TransactionId
btree_xlog_delete_get_latestRemovedXid(XLogReaderState *record)
{
xl_btree_delete *xlrec = (xl_btree_delete *) XLogRecGetData(record);
OffsetNumber *unused;
Buffer ibuffer,
hbuffer;
Page ipage,
hpage;
RelFileNode rnode;
BlockNumber blkno;
ItemId iitemid,
hitemid;
IndexTuple itup;
HeapTupleHeader htuphdr;
BlockNumber hblkno;
OffsetNumber hoffnum;
TransactionId latestRemovedXid = InvalidTransactionId;
int i;
/*
* If there's nothing running on the standby we don't need to derive a
* full latestRemovedXid value, so use a fast path out of here. This
* returns InvalidTransactionId, and so will conflict with all HS
* transactions; but since we just worked out that that's zero people,
* it's OK.
*
* XXX There is a race condition here, which is that a new backend might
* start just after we look. If so, it cannot need to conflict, but this
* coding will result in throwing a conflict anyway.
*/
if (CountDBBackends(InvalidOid) == 0)
return latestRemovedXid;
/*
* In what follows, we have to examine the previous state of the index
* page, as well as the heap page(s) it points to. This is only valid if
* WAL replay has reached a consistent database state; which means that
* the preceding check is not just an optimization, but is *necessary*. We
* won't have let in any user sessions before we reach consistency.
*/
if (!reachedConsistency)
elog(PANIC, "btree_xlog_delete_get_latestRemovedXid: cannot operate with inconsistent data");
/*
* Get index page. If the DB is consistent, this should not fail, nor
* should any of the heap page fetches below. If one does, we return
* InvalidTransactionId to cancel all HS transactions. That's probably
* overkill, but it's safe, and certainly better than panicking here.
*/
XLogRecGetBlockTag(record, 0, &rnode, NULL, &blkno);
ibuffer = XLogReadBufferExtended(rnode, MAIN_FORKNUM, blkno, RBM_NORMAL);
if (!BufferIsValid(ibuffer))
return InvalidTransactionId;
LockBuffer(ibuffer, BT_READ);
ipage = (Page) BufferGetPage(ibuffer);
/*
* Loop through the deleted index items to obtain the TransactionId from
* the heap items they point to.
*/
unused = (OffsetNumber *) ((char *) xlrec + SizeOfBtreeDelete);
for (i = 0; i < xlrec->nitems; i++)
{
/*
* Identify the index tuple about to be deleted
*/
iitemid = PageGetItemId(ipage, unused[i]);
itup = (IndexTuple) PageGetItem(ipage, iitemid);
/*
* Locate the heap page that the index tuple points at
*/
hblkno = ItemPointerGetBlockNumber(&(itup->t_tid));
hbuffer = XLogReadBufferExtended(xlrec->hnode, MAIN_FORKNUM, hblkno, RBM_NORMAL);
if (!BufferIsValid(hbuffer))
{
UnlockReleaseBuffer(ibuffer);
return InvalidTransactionId;
}
LockBuffer(hbuffer, BUFFER_LOCK_SHARE);
hpage = (Page) BufferGetPage(hbuffer);
/*
* Look up the heap tuple header that the index tuple points at by
* using the heap node supplied with the xlrec. We can't use
* heap_fetch, since it uses ReadBuffer rather than XLogReadBuffer.
* Note that we are not looking at tuple data here, just headers.
*/
hoffnum = ItemPointerGetOffsetNumber(&(itup->t_tid));
hitemid = PageGetItemId(hpage, hoffnum);
/*
* Follow any redirections until we find something useful.
*/
while (ItemIdIsRedirected(hitemid))
{
hoffnum = ItemIdGetRedirect(hitemid);
hitemid = PageGetItemId(hpage, hoffnum);
CHECK_FOR_INTERRUPTS();
}
/*
* If the heap item has storage, then read the header and use that to
* set latestRemovedXid.
*
* Some LP_DEAD items may not be accessible, so we ignore them.
*/
if (ItemIdHasStorage(hitemid))
{
htuphdr = (HeapTupleHeader) PageGetItem(hpage, hitemid);
HeapTupleHeaderAdvanceLatestRemovedXid(htuphdr, &latestRemovedXid);
}
else if (ItemIdIsDead(hitemid))
{
/*
* Conjecture: if hitemid is dead then it had xids before the xids
* marked on LP_NORMAL items. So we just ignore this item and move
* onto the next, for the purposes of calculating
* latestRemovedxids.
*/
}
else
Assert(!ItemIdIsUsed(hitemid));
UnlockReleaseBuffer(hbuffer);
}
UnlockReleaseBuffer(ibuffer);
/*
* If all heap tuples were LP_DEAD then we will be returning
* InvalidTransactionId here, which avoids conflicts. This matches
* existing logic which assumes that LP_DEAD tuples must already be older
* than the latestRemovedXid on the cleanup record that set them as
* LP_DEAD, hence must already have generated a conflict.
*/
return latestRemovedXid;
}
/*
* Returns a list of items whose visibility map information does not match
* the status of the tuples on the page.
*
* If all_visible is passed as true, this will include all items which are
* on pages marked as all-visible in the visibility map but which do not
* seem to in fact be all-visible.
*
* If all_frozen is passed as true, this will include all items which are
* on pages marked as all-frozen but which do not seem to in fact be frozen.
*/
static corrupt_items *
collect_corrupt_items(Oid relid, bool all_visible, bool all_frozen)
{
Relation rel;
BlockNumber nblocks;
corrupt_items *items;
BlockNumber blkno;
Buffer vmbuffer = InvalidBuffer;
BufferAccessStrategy bstrategy = GetAccessStrategy(BAS_BULKREAD);
TransactionId OldestXmin = InvalidTransactionId;
if (all_visible)
{
/* Don't pass rel; that will fail in recovery. */
OldestXmin = GetOldestXmin(NULL, true);
}
rel = relation_open(relid, AccessShareLock);
if (rel->rd_rel->relkind != RELKIND_RELATION &&
rel->rd_rel->relkind != RELKIND_MATVIEW &&
rel->rd_rel->relkind != RELKIND_TOASTVALUE)
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("\"%s\" is not a table, materialized view, or TOAST table",
RelationGetRelationName(rel))));
nblocks = RelationGetNumberOfBlocks(rel);
/*
* Guess an initial array size. We don't expect many corrupted tuples, so
* start with a small array. This function uses the "next" field to track
* the next offset where we can store an item (which is the same thing as
* the number of items found so far) and the "count" field to track the
* number of entries allocated. We'll repurpose these fields before
* returning.
*/
items = palloc0(sizeof(corrupt_items));
items->next = 0;
items->count = 64;
items->tids = palloc(items->count * sizeof(ItemPointerData));
/* Loop over every block in the relation. */
for (blkno = 0; blkno < nblocks; ++blkno)
{
bool check_frozen = false;
bool check_visible = false;
Buffer buffer;
Page page;
OffsetNumber offnum,
maxoff;
/* Make sure we are interruptible. */
CHECK_FOR_INTERRUPTS();
/* Use the visibility map to decide whether to check this page. */
if (all_frozen && VM_ALL_FROZEN(rel, blkno, &vmbuffer))
check_frozen = true;
if (all_visible && VM_ALL_VISIBLE(rel, blkno, &vmbuffer))
check_visible = true;
if (!check_visible && !check_frozen)
continue;
/* Read and lock the page. */
buffer = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL,
bstrategy);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
page = BufferGetPage(buffer);
maxoff = PageGetMaxOffsetNumber(page);
/*
* The visibility map bits might have changed while we were acquiring
* the page lock. Recheck to avoid returning spurious results.
*/
if (check_frozen && !VM_ALL_FROZEN(rel, blkno, &vmbuffer))
check_frozen = false;
if (check_visible && !VM_ALL_VISIBLE(rel, blkno, &vmbuffer))
check_visible = false;
if (!check_visible && !check_frozen)
{
UnlockReleaseBuffer(buffer);
continue;
}
/* Iterate over each tuple on the page. */
for (offnum = FirstOffsetNumber;
offnum <= maxoff;
offnum = OffsetNumberNext(offnum))
{
HeapTupleData tuple;
ItemId itemid;
itemid = PageGetItemId(page, offnum);
/* Unused or redirect line pointers are of no interest. */
if (!ItemIdIsUsed(itemid) || ItemIdIsRedirected(itemid))
continue;
/* Dead line pointers are neither all-visible nor frozen. */
if (ItemIdIsDead(itemid))
{
ItemPointerSet(&(tuple.t_self), blkno, offnum);
record_corrupt_item(items, &tuple.t_self);
continue;
}
/* Initialize a HeapTupleData structure for checks below. */
ItemPointerSet(&(tuple.t_self), blkno, offnum);
tuple.t_data = (HeapTupleHeader) PageGetItem(page, itemid);
tuple.t_len = ItemIdGetLength(itemid);
tuple.t_tableOid = relid;
/*
* If we're checking whether the page is all-visible, we expect
* the tuple to be all-visible.
*/
if (check_visible &&
!tuple_all_visible(&tuple, OldestXmin, buffer))
{
TransactionId RecomputedOldestXmin;
/*
* Time has passed since we computed OldestXmin, so it's
* possible that this tuple is all-visible in reality even
* though it doesn't appear so based on our
* previously-computed value. Let's compute a new value so we
* can be certain whether there is a problem.
*
* From a concurrency point of view, it sort of sucks to
* retake ProcArrayLock here while we're holding the buffer
* exclusively locked, but it should be safe against
* deadlocks, because surely GetOldestXmin() should never take
* a buffer lock. And this shouldn't happen often, so it's
* worth being careful so as to avoid false positives.
*/
RecomputedOldestXmin = GetOldestXmin(NULL, true);
if (!TransactionIdPrecedes(OldestXmin, RecomputedOldestXmin))
record_corrupt_item(items, &tuple.t_self);
else
{
OldestXmin = RecomputedOldestXmin;
if (!tuple_all_visible(&tuple, OldestXmin, buffer))
record_corrupt_item(items, &tuple.t_self);
}
}
/*
* If we're checking whether the page is all-frozen, we expect the
* tuple to be in a state where it will never need freezing.
*/
if (check_frozen)
{
if (heap_tuple_needs_eventual_freeze(tuple.t_data))
record_corrupt_item(items, &tuple.t_self);
}
}
UnlockReleaseBuffer(buffer);
}
/* Clean up. */
if (vmbuffer != InvalidBuffer)
ReleaseBuffer(vmbuffer);
relation_close(rel, AccessShareLock);
/*
* Before returning, repurpose the fields to match caller's expectations.
* next is now the next item that should be read (rather than written) and
* count is now the number of items we wrote (rather than the number we
* allocated).
*/
items->count = items->next;
items->next = 0;
return items;
}
/*
* 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);
}
}
}
/*
* 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.
*
* Returns number of unused line pointers on page. If "unused" is not NULL
* then the unused[] array is filled with indexes of unused line pointers.
*/
int
PageRepairFragmentation(Page page, OffsetNumber *unused)
{
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,
nused;
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),
errSendAlert(true)));
nline = PageGetMaxOffsetNumber(page);
nused = 0;
for (i = 0; i < nline; i++)
{
lp = PageGetItemId(page, i + 1);
if (ItemIdDeleted(lp)) /* marked for deletion */
lp->lp_flags &= ~(LP_USED | LP_DELETE);
if (ItemIdIsUsed(lp))
nused++;
else if (unused)
unused[i - nused] = (OffsetNumber) i;
}
if (nused == 0)
{
/* Page is completely empty, so just reset it quickly */
for (i = 0; i < nline; i++)
{
lp = PageGetItemId(page, i + 1);
lp->lp_len = 0; /* indicate unused & deallocated */
}
((PageHeader) page)->pd_upper = pd_special;
}
else
{ /* nused != 0 */
/* Need to compact the page the hard way */
itemidbase = (itemIdSort) palloc(sizeof(itemIdSortData) * nused);
itemidptr = itemidbase;
totallen = 0;
for (i = 0; i < nline; i++)
{
lp = PageGetItemId(page, i + 1);
if (ItemIdIsUsed(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),
errSendAlert(true)));
itemidptr->alignedlen = MAXALIGN(ItemIdGetLength(lp));
totallen += itemidptr->alignedlen;
itemidptr++;
}
else
{
lp->lp_len = 0; /* indicate unused & deallocated */
}
}
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),
errSendAlert(true)));
/* sort itemIdSortData array into decreasing itemoff order */
qsort((char *) itemidbase, nused, sizeof(itemIdSortData),
itemoffcompare);
/* compactify page */
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->lp_off = upper;
}
((PageHeader) page)->pd_upper = upper;
pfree(itemidbase);
}
/* Set hint bit for PageAddItem */
if (nused < nline)
PageSetHasFreeLinePointers(page);
else
PageClearHasFreeLinePointers(page);
return (nline - nused);
}
/*
* 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)
{
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--;
buf = ReadBufferExtended(onerel, MAIN_FORKNUM, blkno,
RBM_NORMAL, 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);
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);
/* 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;
}
/* ----------------------------------------------------------------
* BitmapHeapNext
*
* Retrieve next tuple from the BitmapHeapScan node's currentRelation
* ----------------------------------------------------------------
*/
static TupleTableSlot *
BitmapHeapNext(BitmapHeapScanState *node)
{
EState *estate;
ExprContext *econtext;
HeapScanDesc scan;
Index scanrelid;
TIDBitmap *tbm;
TBMIterateResult *tbmres;
OffsetNumber targoffset;
TupleTableSlot *slot;
/*
* extract necessary information from index scan node
*/
estate = node->ss.ps.state;
econtext = node->ss.ps.ps_ExprContext;
slot = node->ss.ss_ScanTupleSlot;
scan = node->ss.ss_currentScanDesc;
scanrelid = ((BitmapHeapScan *) node->ss.ps.plan)->scan.scanrelid;
tbm = node->tbm;
tbmres = node->tbmres;
/*
* Check if we are evaluating PlanQual for tuple of this relation.
* Additional checking is not good, but no other way for now. We could
* introduce new nodes for this case and handle IndexScan --> NewNode
* switching in Init/ReScan plan...
*/
if (estate->es_evTuple != NULL &&
estate->es_evTuple[scanrelid - 1] != NULL)
{
if (estate->es_evTupleNull[scanrelid - 1])
return ExecClearTuple(slot);
ExecStoreTuple(estate->es_evTuple[scanrelid - 1],
slot, InvalidBuffer, false);
/* Does the tuple meet the original qual conditions? */
econtext->ecxt_scantuple = slot;
ResetExprContext(econtext);
if (!ExecQual(node->bitmapqualorig, econtext, false))
ExecClearTuple(slot); /* would not be returned by scan */
/* Flag for the next call that no more tuples */
estate->es_evTupleNull[scanrelid - 1] = true;
return slot;
}
/*
* If we haven't yet performed the underlying index scan, do it, and
* prepare the bitmap to be iterated over.
*/
if (tbm == NULL)
{
tbm = (TIDBitmap *) MultiExecProcNode(outerPlanState(node));
if (!tbm || !IsA(tbm, TIDBitmap))
elog(ERROR, "unrecognized result from subplan");
node->tbm = tbm;
node->tbmres = tbmres = NULL;
tbm_begin_iterate(tbm);
}
for (;;)
{
Page dp;
ItemId lp;
/*
* Get next page of results if needed
*/
if (tbmres == NULL)
{
node->tbmres = tbmres = tbm_iterate(tbm);
if (tbmres == NULL)
{
/* no more entries in the bitmap */
break;
}
/*
* 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;
}
else
{
/*
* Continuing in previously obtained page; advance rs_cindex
*/
scan->rs_cindex++;
}
/*
* 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;
}
/*
* Okay to fetch the tuple
*/
targoffset = scan->rs_vistuples[scan->rs_cindex];
dp = (Page) BufferGetPage(scan->rs_cbuf);
lp = PageGetItemId(dp, targoffset);
Assert(ItemIdIsUsed(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_pgstat_info);
/*
* 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->ntuples < 0)
{
econtext->ecxt_scantuple = slot;
ResetExprContext(econtext);
if (!ExecQual(node->bitmapqualorig, econtext, false))
{
/* Fails recheck, so drop it and loop back for another */
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);
}
/*
* PageIndexDeleteNoCompact
* Delete the given items for an index page, and defragment the resulting
* free space, but do not compact the item pointers array.
*
* itemnos is the array of tuples to delete; nitems is its size. maxIdxTuples
* is the maximum number of tuples that can exist in a page.
*
* Unused items at the end of the array are removed.
*
* This is used for index AMs that require that existing TIDs of live tuples
* remain unchanged.
*/
void
PageIndexDeleteNoCompact(Page page, OffsetNumber *itemnos, int nitems)
{
PageHeader phdr = (PageHeader) page;
LocationIndex pd_lower = phdr->pd_lower;
LocationIndex pd_upper = phdr->pd_upper;
LocationIndex pd_special = phdr->pd_special;
int nline;
bool empty;
OffsetNumber offnum;
int nextitm;
/*
* 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 existing item pointer array and mark as unused those that are
* in our kill-list; make sure any non-interesting ones are marked unused
* as well.
*/
nline = PageGetMaxOffsetNumber(page);
empty = true;
nextitm = 0;
for (offnum = FirstOffsetNumber; offnum <= nline; offnum = OffsetNumberNext(offnum))
{
ItemId lp;
ItemLength itemlen;
ItemOffset offset;
lp = PageGetItemId(page, offnum);
itemlen = ItemIdGetLength(lp);
offset = ItemIdGetOffset(lp);
if (ItemIdIsUsed(lp))
{
if (offset < pd_upper ||
(offset + itemlen) > pd_special ||
offset != MAXALIGN(offset))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("corrupted item pointer: offset = %u, length = %u",
offset, (unsigned int) itemlen)));
if (nextitm < nitems && offnum == itemnos[nextitm])
{
/* this one is on our list to delete, so mark it unused */
ItemIdSetUnused(lp);
nextitm++;
}
else if (ItemIdHasStorage(lp))
{
/* This one's live -- must do the compaction dance */
empty = false;
}
else
{
/* get rid of this one too */
ItemIdSetUnused(lp);
}
}
}
/* this will catch invalid or out-of-order itemnos[] */
if (nextitm != nitems)
elog(ERROR, "incorrect index offsets supplied");
if (empty)
{
/* Page is completely empty, so just reset it quickly */
phdr->pd_lower = SizeOfPageHeaderData;
phdr->pd_upper = pd_special;
}
else
{
/* There are live items: need to compact the page the hard way */
itemIdSortData itemidbase[MaxOffsetNumber];
itemIdSort itemidptr;
int i;
Size totallen;
/*
* Scan the page taking note of each item that we need to preserve.
* This includes both live items (those that contain data) and
* interspersed unused ones. It's critical to preserve these unused
* items, because otherwise the offset numbers for later live items
* would change, which is not acceptable. Unused items might get used
* again later; that is fine.
*/
itemidptr = itemidbase;
totallen = 0;
PageClearHasFreeLinePointers(page);
for (i = 0; i < nline; i++)
{
ItemId lp;
itemidptr->offsetindex = i;
lp = PageGetItemId(page, i + 1);
if (ItemIdHasStorage(lp))
{
itemidptr->itemoff = ItemIdGetOffset(lp);
itemidptr->alignedlen = MAXALIGN(ItemIdGetLength(lp));
totallen += itemidptr->alignedlen;
itemidptr++;
}
else
{
PageSetHasFreeLinePointers(page);
ItemIdSetUnused(lp);
}
}
nline = itemidptr - itemidbase;
/* By here, there are exactly nline elements in itemidbase array */
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)));
/*
* Defragment the data areas of each tuple, being careful to preserve
* each item's position in the linp array.
*/
compactify_tuples(itemidbase, nline, page);
}
}
/*
* 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;
}
/*
* Extract all item values from a BRIN index page
*
* Usage: SELECT * FROM brin_page_items(get_raw_page('idx', 1), 'idx'::regclass);
*/
Datum
brin_page_items(PG_FUNCTION_ARGS)
{
brin_page_state *state;
FuncCallContext *fctx;
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
(errmsg("must be superuser to use raw page functions"))));
if (SRF_IS_FIRSTCALL())
{
bytea *raw_page = PG_GETARG_BYTEA_P(0);
Oid indexRelid = PG_GETARG_OID(1);
Page page;
TupleDesc tupdesc;
MemoryContext mctx;
Relation indexRel;
AttrNumber attno;
/* minimally verify the page we got */
page = verify_brin_page(raw_page, BRIN_PAGETYPE_REGULAR, "regular");
/* create a function context for cross-call persistence */
fctx = SRF_FIRSTCALL_INIT();
/* switch to memory context appropriate for multiple function calls */
mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
/* Build a tuple descriptor for our result type */
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
indexRel = index_open(indexRelid, AccessShareLock);
state = palloc(offsetof(brin_page_state, columns) +
sizeof(brin_column_state) * RelationGetDescr(indexRel)->natts);
state->bdesc = brin_build_desc(indexRel);
state->page = page;
state->offset = FirstOffsetNumber;
state->unusedItem = false;
state->done = false;
state->dtup = NULL;
/*
* Initialize output functions for all indexed datatypes; simplifies
* calling them later.
*/
for (attno = 1; attno <= state->bdesc->bd_tupdesc->natts; attno++)
{
Oid output;
bool isVarlena;
BrinOpcInfo *opcinfo;
int i;
brin_column_state *column;
opcinfo = state->bdesc->bd_info[attno - 1];
column = palloc(offsetof(brin_column_state, outputFn) +
sizeof(FmgrInfo) * opcinfo->oi_nstored);
column->nstored = opcinfo->oi_nstored;
for (i = 0; i < opcinfo->oi_nstored; i++)
{
getTypeOutputInfo(opcinfo->oi_typcache[i]->type_id, &output, &isVarlena);
fmgr_info(output, &column->outputFn[i]);
}
state->columns[attno - 1] = column;
}
index_close(indexRel, AccessShareLock);
fctx->user_fctx = state;
fctx->tuple_desc = BlessTupleDesc(tupdesc);
MemoryContextSwitchTo(mctx);
}
fctx = SRF_PERCALL_SETUP();
state = fctx->user_fctx;
if (!state->done)
{
HeapTuple result;
Datum values[7];
bool nulls[7];
/*
* This loop is called once for every attribute of every tuple in the
* page. At the start of a tuple, we get a NULL dtup; that's our
* signal for obtaining and decoding the next one. If that's not the
* case, we output the next attribute.
*/
if (state->dtup == NULL)
{
BrinTuple *tup;
MemoryContext mctx;
ItemId itemId;
/* deformed tuple must live across calls */
mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx);
/* verify item status: if there's no data, we can't decode */
itemId = PageGetItemId(state->page, state->offset);
if (ItemIdIsUsed(itemId))
{
tup = (BrinTuple *) PageGetItem(state->page,
PageGetItemId(state->page,
state->offset));
state->dtup = brin_deform_tuple(state->bdesc, tup);
state->attno = 1;
state->unusedItem = false;
}
else
state->unusedItem = true;
MemoryContextSwitchTo(mctx);
}
else
state->attno++;
MemSet(nulls, 0, sizeof(nulls));
if (state->unusedItem)
{
values[0] = UInt16GetDatum(state->offset);
nulls[1] = true;
nulls[2] = true;
nulls[3] = true;
nulls[4] = true;
nulls[5] = true;
nulls[6] = true;
}
else
{
int att = state->attno - 1;
values[0] = UInt16GetDatum(state->offset);
values[1] = UInt32GetDatum(state->dtup->bt_blkno);
values[2] = UInt16GetDatum(state->attno);
values[3] = BoolGetDatum(state->dtup->bt_columns[att].bv_allnulls);
values[4] = BoolGetDatum(state->dtup->bt_columns[att].bv_hasnulls);
values[5] = BoolGetDatum(state->dtup->bt_placeholder);
if (!state->dtup->bt_columns[att].bv_allnulls)
{
BrinValues *bvalues = &state->dtup->bt_columns[att];
StringInfoData s;
bool first;
int i;
initStringInfo(&s);
appendStringInfoChar(&s, '{');
first = true;
for (i = 0; i < state->columns[att]->nstored; i++)
{
char *val;
if (!first)
appendStringInfoString(&s, " .. ");
first = false;
val = OutputFunctionCall(&state->columns[att]->outputFn[i],
bvalues->bv_values[i]);
appendStringInfoString(&s, val);
pfree(val);
}
appendStringInfoChar(&s, '}');
values[6] = CStringGetTextDatum(s.data);
pfree(s.data);
}
else
{
nulls[6] = true;
}
}
result = heap_form_tuple(fctx->tuple_desc, values, nulls);
/*
* If the item was unused, jump straight to the next one; otherwise,
* the only cleanup needed here is to set our signal to go to the next
* tuple in the following iteration, by freeing the current one.
*/
if (state->unusedItem)
state->offset = OffsetNumberNext(state->offset);
else if (state->attno >= state->bdesc->bd_tupdesc->natts)
{
pfree(state->dtup);
state->dtup = NULL;
state->offset = OffsetNumberNext(state->offset);
}
/*
* If we're beyond the end of the page, set flag to end the function
* in the following iteration.
*/
if (state->offset > PageGetMaxOffsetNumber(state->page))
state->done = true;
SRF_RETURN_NEXT(fctx, HeapTupleGetDatum(result));
}
brin_free_desc(state->bdesc);
SRF_RETURN_DONE(fctx);
}
/*
* 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)
{
BlockNumber blkno;
instr_time starttime;
instr_time currenttime;
instr_time elapsed;
/* Initialize the starttime if we check for conflicting lock requests */
INSTR_TIME_SET_CURRENT(starttime);
/* 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;
/*
* Check if another process requests a lock on our relation. We are
* holding an AccessExclusiveLock here, so they will be waiting. We
* only do this in autovacuum_truncate_lock_check millisecond
* intervals, and we only check if that interval has elapsed once
* every 32 blocks to keep the number of system calls and actual
* shared lock table lookups to a minimum.
*/
if ((blkno % 32) == 0)
{
INSTR_TIME_SET_CURRENT(currenttime);
elapsed = currenttime;
INSTR_TIME_SUBTRACT(elapsed, starttime);
if ((INSTR_TIME_GET_MICROSEC(elapsed) / 1000)
>= AUTOVACUUM_TRUNCATE_LOCK_CHECK_INTERVAL)
{
if (LockHasWaitersRelation(onerel, AccessExclusiveLock))
{
ereport(elevel,
(errmsg("\"%s\": suspending truncate "
"due to conflicting lock request",
RelationGetRelationName(onerel))));
vacrelstats->lock_waiter_detected = true;
return blkno;
}
starttime = currenttime;
}
}
/*
* 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--;
buf = ReadBufferExtended(onerel, MAIN_FORKNUM, blkno,
RBM_NORMAL, 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);
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);
/* 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;
}
/*
* 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;
ItemId lp;
int nline,
nstorage,
nunused;
int i;
Size totallen;
/*
* 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
{
/* Need to compact the page the hard way */
itemIdSortData itemidbase[MaxHeapTuplesPerPage];
itemIdSort 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)));
compactify_tuples(itemidbase, nstorage, page);
}
/* Set hint bit for PageAddItem */
if (nunused > 0)
PageSetHasFreeLinePointers(page);
else
PageClearHasFreeLinePointers(page);
}
/*
* 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)
{
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++)
lazy_vacuum_index(Irel[i], &indstats[i], vacrelstats);
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, false))
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);
}
}
/*
* 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++)
lazy_vacuum_index(Irel[i], &indstats[i], vacrelstats);
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))));
}
/*
* 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;
Page dp;
int ntup;
int curslot;
int minslot;
int maxslot;
int maxoff;
/*
* 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;
/*
* 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);
dp = (Page) BufferGetPage(buffer);
maxoff = PageGetMaxOffsetNumber(dp);
/*
* Determine how many entries we need to look at on this page. If the
* bitmap is lossy then we need to look at each physical item pointer;
* otherwise we just look through the offsets listed in tbmres.
*/
if (tbmres->ntuples >= 0)
{
/* non-lossy case */
minslot = 0;
maxslot = tbmres->ntuples - 1;
}
else
{
/* lossy case */
minslot = FirstOffsetNumber;
maxslot = maxoff;
}
ntup = 0;
for (curslot = minslot; curslot <= maxslot; curslot++)
{
OffsetNumber targoffset;
ItemId lp;
HeapTupleData loctup;
bool valid;
if (tbmres->ntuples >= 0)
{
/* non-lossy case */
targoffset = tbmres->offsets[curslot];
}
else
{
/* lossy case */
targoffset = (OffsetNumber) curslot;
}
/*
* We'd better check for out-of-range offnum in case of VACUUM since
* the TID was obtained.
*/
if (targoffset < FirstOffsetNumber || targoffset > maxoff)
continue;
lp = PageGetItemId(dp, targoffset);
/*
* Must check for deleted tuple.
*/
if (!ItemIdIsUsed(lp))
continue;
/*
* check time qualification of tuple, remember it if valid
*/
loctup.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
loctup.t_len = ItemIdGetLength(lp);
ItemPointerSet(&(loctup.t_self), page, targoffset);
valid = HeapTupleSatisfiesVisibility(&loctup, snapshot, buffer);
if (valid)
scan->rs_vistuples[ntup++] = targoffset;
}
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
Assert(ntup <= MaxHeapTuplesPerPage);
scan->rs_ntuples = ntup;
}
/*
* 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, 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;
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();
vacrelstats->scanned_pages++;
/*
* 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)
{
/* 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++;
}
buf = ReadBufferExtended(onerel, MAIN_FORKNUM, blkno,
RBM_NORMAL, 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);
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);
if (!PageIsAllVisible(page))
{
PageSetAllVisible(page);
SetBufferCommitInfoNeedsSave(buf);
}
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
/* Update the visibility map */
if (!all_visible_according_to_vm)
{
visibilitymap_pin(onerel, blkno, &vmbuffer);
LockBuffer(buf, BUFFER_LOCK_SHARE);
if (PageIsAllVisible(page))
visibilitymap_set(onerel, blkno, PageGetLSN(page), &vmbuffer);
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
}
ReleaseBuffer(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;
}
}
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,
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);
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);
/* Update the all-visible flag on the page */
if (!PageIsAllVisible(page) && all_visible)
{
PageSetAllVisible(page);
SetBufferCommitInfoNeedsSave(buf);
}
/*
* 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);
SetBufferCommitInfoNeedsSave(buf);
/*
* Normally, we would drop the lock on the heap page before
* updating the visibility map, but since this case shouldn't
* happen anyway, don't worry about that.
*/
visibilitymap_clear(onerel, blkno);
}
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
/* Update the visibility map */
if (!all_visible_according_to_vm && all_visible)
{
visibilitymap_pin(onerel, blkno, &vmbuffer);
LockBuffer(buf, BUFFER_LOCK_SHARE);
if (PageIsAllVisible(page))
visibilitymap_set(onerel, blkno, PageGetLSN(page), &vmbuffer);
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
}
ReleaseBuffer(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))));
}
/*
* 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 redirect_move is set, we remove redirecting line pointers by
* updating the root line pointer to point directly to the first non-dead
* tuple in the chain. NOTE: eliminating the redirect changes the first
* tuple's effective CTID, and is therefore unsafe except within VACUUM FULL.
* The only reason we support this capability at all is that by using it,
* VACUUM FULL need not cope with LP_REDIRECT items at all; which seems a
* good thing since VACUUM FULL is overly complicated already.
*
* 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.
*/
int
heap_page_prune(Relation relation, Buffer buffer, TransactionId OldestXmin,
bool redirect_move, bool report_stats)
{
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, inform inval.c that upcoming CacheInvalidateHeapTuple calls are
* nontransactional.
*/
if (redirect_move)
BeginNonTransactionalInvalidation();
/*
* 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.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,
redirect_move);
}
/*
* Send invalidation messages for any tuples we are about to move. It is
* safe to do this now, even though we could theoretically still fail
* before making the actual page update, because a useless cache
* invalidation doesn't hurt anything. Also, no one else can reload the
* tuples while we have exclusive buffer lock, so it's not too early to
* send the invals. This avoids sending the invals while inside the
* critical section, which is a good thing for robustness.
*/
if (redirect_move)
EndNonTransactionalInvalidation();
/* 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,
redirect_move);
/*
* 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 or HEAP_CLEAN_MOVE record showing what we did
*/
if (!relation->rd_istemp)
{
XLogRecPtr recptr;
recptr = log_heap_clean(relation, buffer,
prstate.redirected, prstate.nredirected,
prstate.nowdead, prstate.ndead,
prstate.nowunused, prstate.nunused,
redirect_move);
PageSetLSN(BufferGetPage(buffer), recptr);
}
}
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);
MarkBufferDirtyHint(buffer, relation);
}
}
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);
/*
* 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.
*
* In any case, the current FSM implementation doesn't accept
* one-page-at-a-time updates, so this is all academic for now.
*/
return ndeleted;
}
/*
* Extract all item values from a BRIN index page
*
* Usage: SELECT * FROM brin_page_items(get_raw_page('idx', 1), 'idx'::regclass);
*/
Datum
brin_page_items(PG_FUNCTION_ARGS)
{
bytea *raw_page = PG_GETARG_BYTEA_P(0);
Oid indexRelid = PG_GETARG_OID(1);
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
TupleDesc tupdesc;
MemoryContext oldcontext;
Tuplestorestate *tupstore;
Relation indexRel;
brin_column_state **columns;
BrinDesc *bdesc;
BrinMemTuple *dtup;
Page page;
OffsetNumber offset;
AttrNumber attno;
bool unusedItem;
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
(errmsg("must be superuser to use raw page functions"))));
/* check to see if caller supports us returning a tuplestore */
if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("set-valued function called in context that cannot accept a set")));
if (!(rsinfo->allowedModes & SFRM_Materialize) ||
rsinfo->expectedDesc == NULL)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("materialize mode required, but it is not allowed in this context")));
/* Build a tuple descriptor for our result type */
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
/* Build tuplestore to hold the result rows */
oldcontext = MemoryContextSwitchTo(rsinfo->econtext->ecxt_per_query_memory);
tupstore = tuplestore_begin_heap(true, false, work_mem);
rsinfo->returnMode = SFRM_Materialize;
rsinfo->setResult = tupstore;
rsinfo->setDesc = tupdesc;
MemoryContextSwitchTo(oldcontext);
indexRel = index_open(indexRelid, AccessShareLock);
bdesc = brin_build_desc(indexRel);
/* minimally verify the page we got */
page = verify_brin_page(raw_page, BRIN_PAGETYPE_REGULAR, "regular");
/*
* Initialize output functions for all indexed datatypes; simplifies
* calling them later.
*/
columns = palloc(sizeof(brin_column_state *) * RelationGetDescr(indexRel)->natts);
for (attno = 1; attno <= bdesc->bd_tupdesc->natts; attno++)
{
Oid output;
bool isVarlena;
BrinOpcInfo *opcinfo;
int i;
brin_column_state *column;
opcinfo = bdesc->bd_info[attno - 1];
column = palloc(offsetof(brin_column_state, outputFn) +
sizeof(FmgrInfo) * opcinfo->oi_nstored);
column->nstored = opcinfo->oi_nstored;
for (i = 0; i < opcinfo->oi_nstored; i++)
{
getTypeOutputInfo(opcinfo->oi_typcache[i]->type_id, &output, &isVarlena);
fmgr_info(output, &column->outputFn[i]);
}
columns[attno - 1] = column;
}
offset = FirstOffsetNumber;
unusedItem = false;
dtup = NULL;
for (;;)
{
Datum values[7];
bool nulls[7];
/*
* This loop is called once for every attribute of every tuple in the
* page. At the start of a tuple, we get a NULL dtup; that's our
* signal for obtaining and decoding the next one. If that's not the
* case, we output the next attribute.
*/
if (dtup == NULL)
{
ItemId itemId;
/* verify item status: if there's no data, we can't decode */
itemId = PageGetItemId(page, offset);
if (ItemIdIsUsed(itemId))
{
dtup = brin_deform_tuple(bdesc,
(BrinTuple *) PageGetItem(page, itemId));
attno = 1;
unusedItem = false;
}
else
unusedItem = true;
}
else
attno++;
MemSet(nulls, 0, sizeof(nulls));
if (unusedItem)
{
values[0] = UInt16GetDatum(offset);
nulls[1] = true;
nulls[2] = true;
nulls[3] = true;
nulls[4] = true;
nulls[5] = true;
nulls[6] = true;
}
else
{
int att = attno - 1;
values[0] = UInt16GetDatum(offset);
values[1] = UInt32GetDatum(dtup->bt_blkno);
values[2] = UInt16GetDatum(attno);
values[3] = BoolGetDatum(dtup->bt_columns[att].bv_allnulls);
values[4] = BoolGetDatum(dtup->bt_columns[att].bv_hasnulls);
values[5] = BoolGetDatum(dtup->bt_placeholder);
if (!dtup->bt_columns[att].bv_allnulls)
{
BrinValues *bvalues = &dtup->bt_columns[att];
StringInfoData s;
bool first;
int i;
initStringInfo(&s);
appendStringInfoChar(&s, '{');
first = true;
for (i = 0; i < columns[att]->nstored; i++)
{
char *val;
if (!first)
appendStringInfoString(&s, " .. ");
first = false;
val = OutputFunctionCall(&columns[att]->outputFn[i],
bvalues->bv_values[i]);
appendStringInfoString(&s, val);
pfree(val);
}
appendStringInfoChar(&s, '}');
values[6] = CStringGetTextDatum(s.data);
pfree(s.data);
}
else
{
nulls[6] = true;
}
}
tuplestore_putvalues(tupstore, tupdesc, values, nulls);
/*
* If the item was unused, jump straight to the next one; otherwise,
* the only cleanup needed here is to set our signal to go to the next
* tuple in the following iteration, by freeing the current one.
*/
if (unusedItem)
offset = OffsetNumberNext(offset);
else if (attno >= bdesc->bd_tupdesc->natts)
{
pfree(dtup);
dtup = NULL;
offset = OffsetNumberNext(offset);
}
/*
* If we're beyond the end of the page, we're done.
*/
if (offset > PageGetMaxOffsetNumber(page))
break;
}
/* clean up and return the tuplestore */
brin_free_desc(bdesc);
tuplestore_donestoring(tupstore);
index_close(indexRel, AccessShareLock);
return (Datum) 0;
}
/*
* 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[].
*
* If redirect_move is true, we intend to get rid of redirecting line pointers,
* not just make redirection entries.
*
* 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,
bool redirect_move)
{
int ndeleted = 0;
Page dp = (Page) BufferGetPage(buffer);
TransactionId priorXmax = InvalidTransactionId;
ItemId rootlp;
HeapTupleHeader htup;
OffsetNumber latestdead = InvalidOffsetNumber,
redirect_target = 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(relation, htup, OldestXmin, buffer)
== HEAPTUPLE_DEAD && !HeapTupleHeaderIsHotUpdated(htup))
{
heap_prune_record_unused(prstate, rootoffnum);
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(relation, 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;
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]);
/* If the redirection will be a move, need more processing */
if (redirect_move)
redirect_target = 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);
}
else if (redirect_move && ItemIdIsRedirected(rootlp))
{
/*
* If we desire to eliminate LP_REDIRECT items by moving tuples, make
* a redirection entry for each redirected root item; this will cause
* heap_page_prune_execute to actually do the move. (We get here only
* when there are no DEAD tuples in the chain; otherwise the
* redirection entry was made above.)
*/
heap_prune_record_redirect(prstate, rootoffnum, chainitems[1]);
redirect_target = chainitems[1];
}
/*
* If we are going to implement a redirect by moving tuples, we have to
* issue a cache invalidation against the redirection target tuple,
* because its CTID will be effectively changed by the move. Note that
* CacheInvalidateHeapTuple only queues the request, it doesn't send it;
* if we fail before reaching EndNonTransactionalInvalidation, nothing
* happens and no harm is done.
*/
if (OffsetNumberIsValid(redirect_target))
{
ItemId firstlp = PageGetItemId(dp, redirect_target);
HeapTupleData firsttup;
Assert(ItemIdIsNormal(firstlp));
/* Set up firsttup to reference the tuple at its existing CTID */
firsttup.t_data = (HeapTupleHeader) PageGetItem(dp, firstlp);
firsttup.t_len = ItemIdGetLength(firstlp);
ItemPointerSet(&firsttup.t_self,
BufferGetBlockNumber(buffer),
redirect_target);
CacheInvalidateHeapTuple(relation, &firsttup);
}
return ndeleted;
}
