/*
* btvacuumscan --- scan the index for VACUUMing purposes
*
* This combines the functions of looking for leaf tuples that are deletable
* according to the vacuum callback, looking for empty pages that can be
* deleted, and looking for old deleted pages that can be recycled. Both
* btbulkdelete and btvacuumcleanup invoke this (the latter only if no
* btbulkdelete call occurred).
*
* The caller is responsible for initially allocating/zeroing a stats struct
* and for obtaining a vacuum cycle ID if necessary.
*/
static void
btvacuumscan(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
IndexBulkDeleteCallback callback, void *callback_state,
BTCycleId cycleid)
{
MIRROREDLOCK_BUFMGR_VERIFY_NO_LOCK_LEAK_DECLARE;
Relation rel = info->index;
BTVacState vstate;
BlockNumber num_pages;
BlockNumber blkno;
bool needLock;
MIRROREDLOCK_BUFMGR_VERIFY_NO_LOCK_LEAK_ENTER;
/*
* Reset counts that will be incremented during the scan; needed in case
* of multiple scans during a single VACUUM command
*/
stats->num_index_tuples = 0;
stats->pages_deleted = 0;
/* Set up info to pass down to btvacuumpage */
vstate.info = info;
vstate.stats = stats;
vstate.callback = callback;
vstate.callback_state = callback_state;
vstate.cycleid = cycleid;
vstate.freePages = NULL; /* temporarily */
vstate.nFreePages = 0;
vstate.maxFreePages = 0;
vstate.totFreePages = 0;
/* Create a temporary memory context to run _bt_pagedel in */
vstate.pagedelcontext = AllocSetContextCreate(CurrentMemoryContext,
"_bt_pagedel",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
/*
* The outer loop iterates over all index pages except the metapage, in
* physical order (we hope the kernel will cooperate in providing
* read-ahead for speed). It is critical that we visit all leaf pages,
* including ones added after we start the scan, else we might fail to
* delete some deletable tuples. Hence, we must repeatedly check the
* relation length. We must acquire the relation-extension lock while
* doing so to avoid a race condition: if someone else is extending the
* relation, there is a window where bufmgr/smgr have created a new
* all-zero page but it hasn't yet been write-locked by _bt_getbuf(). If
* we manage to scan such a page here, we'll improperly assume it can be
* recycled. Taking the lock synchronizes things enough to prevent a
* problem: either num_pages won't include the new page, or _bt_getbuf
* already has write lock on the buffer and it will be fully initialized
* before we can examine it. (See also vacuumlazy.c, which has the same
* issue.) Also, we need not worry if a page is added immediately after
* we look; the page splitting code already has write-lock on the left
* page before it adds a right page, so we must already have processed any
* tuples due to be moved into such a page.
*
* We can skip locking for new or temp relations, however, since no one
* else could be accessing them.
*/
needLock = !RELATION_IS_LOCAL(rel);
blkno = BTREE_METAPAGE + 1;
for (;;)
{
/* Get the current relation length */
if (needLock)
LockRelationForExtension(rel, ExclusiveLock);
num_pages = RelationGetNumberOfBlocks(rel);
if (needLock)
UnlockRelationForExtension(rel, ExclusiveLock);
/* Allocate freePages after we read num_pages the first time */
if (vstate.freePages == NULL)
{
/* No point in remembering more than MaxFSMPages pages */
vstate.maxFreePages = MaxFSMPages;
if ((BlockNumber) vstate.maxFreePages > num_pages)
vstate.maxFreePages = (int) num_pages;
vstate.freePages = (BlockNumber *)
palloc(vstate.maxFreePages * sizeof(BlockNumber));
}
/* Quit if we've scanned the whole relation */
if (blkno >= num_pages)
break;
/* Iterate over pages, then loop back to recheck length */
for (; blkno < num_pages; blkno++)
{
btvacuumpage(&vstate, blkno, blkno);
}
}
/*
* During VACUUM FULL, we truncate off any recyclable pages at the end of
* the index. In a normal vacuum it'd be unsafe to do this except by
* acquiring exclusive lock on the index and then rechecking all the
* pages; doesn't seem worth it.
*/
if (info->vacuum_full && vstate.nFreePages > 0)
{
BlockNumber new_pages = num_pages;
while (vstate.nFreePages > 0 &&
vstate.freePages[vstate.nFreePages - 1] == new_pages - 1)
{
new_pages--;
stats->pages_deleted--;
vstate.nFreePages--;
vstate.totFreePages = vstate.nFreePages; /* can't be more */
}
if (new_pages != num_pages)
{
/*
* Okay to truncate.
*/
RelationTruncate(rel, new_pages,
/* markPersistentAsPhysicallyTruncated */ true);
/* update statistics */
stats->pages_removed += num_pages - new_pages;
num_pages = new_pages;
}
}
/*
* Update the shared Free Space Map with the info we now have about free
* pages in the index, discarding any old info the map may have. We do not
* need to sort the page numbers; they're in order already.
*/
RecordIndexFreeSpace(&rel->rd_node, vstate.totFreePages,
vstate.nFreePages, vstate.freePages);
pfree(vstate.freePages);
MemoryContextDelete(vstate.pagedelcontext);
/* update statistics */
stats->num_pages = num_pages;
stats->pages_free = vstate.totFreePages;
MIRROREDLOCK_BUFMGR_VERIFY_NO_LOCK_LEAK_EXIT;
}
/*
* lazy_truncate_heap - try to truncate off any empty pages at the end
*/
static void
lazy_truncate_heap(Relation onerel, LVRelStats *vacrelstats)
{
BlockNumber old_rel_pages = vacrelstats->rel_pages;
BlockNumber new_rel_pages;
PGRUsage ru0;
pg_rusage_init(&ru0);
/*
* We need full exclusive lock on the relation in order to do truncation.
* If we can't get it, give up rather than waiting --- we don't want to
* block other backends, and we don't want to deadlock (which is quite
* possible considering we already hold a lower-grade lock).
*/
if (!ConditionalLockRelation(onerel, AccessExclusiveLock))
return;
/*
* Now that we have exclusive lock, look to see if the rel has grown
* whilst we were vacuuming with non-exclusive lock. If so, give up; the
* newly added pages presumably contain non-deletable tuples.
*/
new_rel_pages = RelationGetNumberOfBlocks(onerel);
if (new_rel_pages != old_rel_pages)
{
/*
* Note: we intentionally don't update vacrelstats->rel_pages with the
* new rel size here. If we did, it would amount to assuming that the
* new pages are empty, which is unlikely. Leaving the numbers alone
* amounts to assuming that the new pages have the same tuple density
* as existing ones, which is less unlikely.
*/
UnlockRelation(onerel, AccessExclusiveLock);
return;
}
/*
* Scan backwards from the end to verify that the end pages actually
* contain no tuples. This is *necessary*, not optional, because other
* backends could have added tuples to these pages whilst we were
* vacuuming.
*/
new_rel_pages = count_nondeletable_pages(onerel, vacrelstats);
if (new_rel_pages >= old_rel_pages)
{
/* can't do anything after all */
UnlockRelation(onerel, AccessExclusiveLock);
return;
}
/*
* Okay to truncate.
*/
RelationTruncate(onerel, new_rel_pages);
/*
* We can release the exclusive lock as soon as we have truncated. Other
* backends can't safely access the relation until they have processed the
* smgr invalidation that smgrtruncate sent out ... but that should happen
* as part of standard invalidation processing once they acquire lock on
* the relation.
*/
UnlockRelation(onerel, AccessExclusiveLock);
/*
* Update statistics. Here, it *is* correct to adjust rel_pages without
* also touching reltuples, since the tuple count wasn't changed by the
* truncation.
*/
vacrelstats->rel_pages = new_rel_pages;
vacrelstats->pages_removed = old_rel_pages - new_rel_pages;
ereport(elevel,
(errmsg("\"%s\": truncated %u to %u pages",
RelationGetRelationName(onerel),
old_rel_pages, new_rel_pages),
errdetail("%s.",
pg_rusage_show(&ru0))));
}
Datum
gistvacuumcleanup(PG_FUNCTION_ARGS)
{
IndexVacuumInfo *info = (IndexVacuumInfo *) PG_GETARG_POINTER(0);
GistBulkDeleteResult *stats = (GistBulkDeleteResult *) PG_GETARG_POINTER(1);
Relation rel = info->index;
BlockNumber npages,
blkno;
BlockNumber totFreePages,
nFreePages,
*freePages,
maxFreePages;
BlockNumber lastBlock = GIST_ROOT_BLKNO,
lastFilledBlock = GIST_ROOT_BLKNO;
bool needLock;
/* Set up all-zero stats if gistbulkdelete wasn't called */
if (stats == NULL)
{
stats = (GistBulkDeleteResult *) palloc0(sizeof(GistBulkDeleteResult));
/* use heap's tuple count */
Assert(info->num_heap_tuples >= 0);
stats->std.num_index_tuples = info->num_heap_tuples;
/*
* XXX the above is wrong if index is partial. Would it be OK to just
* return NULL, or is there work we must do below?
*/
}
/* gistVacuumUpdate may cause hard work */
if (info->vacuum_full)
{
GistVacuum gv;
ArrayTuple res;
/* note: vacuum.c already acquired AccessExclusiveLock on index */
gv.index = rel;
initGISTstate(&(gv.giststate), rel);
gv.opCtx = createTempGistContext();
gv.result = stats;
gv.strategy = info->strategy;
/* walk through the entire index for update tuples */
res = gistVacuumUpdate(&gv, GIST_ROOT_BLKNO, false);
/* cleanup */
if (res.itup)
{
int i;
for (i = 0; i < res.ituplen; i++)
pfree(res.itup[i]);
pfree(res.itup);
}
freeGISTstate(&(gv.giststate));
MemoryContextDelete(gv.opCtx);
}
else if (stats->needFullVacuum)
ereport(NOTICE,
(errmsg("index \"%s\" needs VACUUM FULL or REINDEX to finish crash recovery",
RelationGetRelationName(rel))));
/*
* If vacuum full, we already have exclusive lock on the index. Otherwise,
* need lock unless it's local to this backend.
*/
if (info->vacuum_full)
needLock = false;
else
needLock = !RELATION_IS_LOCAL(rel);
/* try to find deleted pages */
if (needLock)
LockRelationForExtension(rel, ExclusiveLock);
npages = RelationGetNumberOfBlocks(rel);
if (needLock)
UnlockRelationForExtension(rel, ExclusiveLock);
maxFreePages = npages;
if (maxFreePages > MaxFSMPages)
maxFreePages = MaxFSMPages;
totFreePages = nFreePages = 0;
freePages = (BlockNumber *) palloc(sizeof(BlockNumber) * maxFreePages);
for (blkno = GIST_ROOT_BLKNO + 1; blkno < npages; blkno++)
{
Buffer buffer;
Page page;
vacuum_delay_point();
buffer = ReadBufferWithStrategy(rel, blkno, info->strategy);
LockBuffer(buffer, GIST_SHARE);
page = (Page) BufferGetPage(buffer);
if (PageIsNew(page) || GistPageIsDeleted(page))
{
if (nFreePages < maxFreePages)
freePages[nFreePages++] = blkno;
totFreePages++;
}
else
lastFilledBlock = blkno;
UnlockReleaseBuffer(buffer);
}
lastBlock = npages - 1;
if (info->vacuum_full && nFreePages > 0)
{ /* try to truncate index */
int i;
for (i = 0; i < nFreePages; i++)
if (freePages[i] >= lastFilledBlock)
{
totFreePages = nFreePages = i;
break;
}
if (lastBlock > lastFilledBlock)
RelationTruncate(rel, lastFilledBlock + 1);
stats->std.pages_removed = lastBlock - lastFilledBlock;
}
RecordIndexFreeSpace(&rel->rd_node, totFreePages, nFreePages, freePages);
pfree(freePages);
/* return statistics */
stats->std.pages_free = totFreePages;
if (needLock)
LockRelationForExtension(rel, ExclusiveLock);
stats->std.num_pages = RelationGetNumberOfBlocks(rel);
if (needLock)
UnlockRelationForExtension(rel, ExclusiveLock);
PG_RETURN_POINTER(stats);
}
/*
* lazy_truncate_heap - try to truncate off any empty pages at the end
*/
static void
lazy_truncate_heap(Relation onerel, LVRelStats *vacrelstats)
{
BlockNumber old_rel_pages = vacrelstats->rel_pages;
BlockNumber new_rel_pages;
PageFreeSpaceInfo *pageSpaces;
int n;
int i,
j;
PGRUsage ru0;
/*
* Persistent table TIDs are stored in other locations like gp_relation_node
* and changeTracking logs, which continue to have references to CTID even
* if PT tuple is marked deleted. This TID is used to read tuple during
* crash recovery or segment resyncs. Hence need to avoid truncating
* persistent tables to avoid error / crash in heap_fetch using the TID
* on lazy vacuum.
*/
if (GpPersistent_IsPersistentRelation(RelationGetRelid(onerel)))
return;
pg_rusage_init(&ru0);
/*
* We need full exclusive lock on the relation in order to do truncation.
* If we can't get it, give up rather than waiting --- we don't want to
* block other backends, and we don't want to deadlock (which is quite
* possible considering we already hold a lower-grade lock).
*/
if (!ConditionalLockRelation(onerel, AccessExclusiveLock))
return;
/*
* Now that we have exclusive lock, look to see if the rel has grown
* whilst we were vacuuming with non-exclusive lock. If so, give up; the
* newly added pages presumably contain non-deletable tuples.
*/
new_rel_pages = RelationGetNumberOfBlocks(onerel);
if (new_rel_pages != old_rel_pages)
{
/* might as well use the latest news when we update pg_class stats */
vacrelstats->rel_pages = new_rel_pages;
UnlockRelation(onerel, AccessExclusiveLock);
return;
}
/*
* Scan backwards from the end to verify that the end pages actually
* contain no tuples. This is *necessary*, not optional, because other
* backends could have added tuples to these pages whilst we were
* vacuuming.
*/
new_rel_pages = count_nondeletable_pages(onerel, vacrelstats);
if (new_rel_pages >= old_rel_pages)
{
/* can't do anything after all */
UnlockRelation(onerel, AccessExclusiveLock);
return;
}
/*
* Okay to truncate.
*/
RelationTruncate(
onerel,
new_rel_pages,
/* markPersistentAsPhysicallyTruncated */ true);
/*
* Note: once we have truncated, we *must* keep the exclusive lock until
* commit. The sinval message that will be sent at commit (as a result of
* vac_update_relstats()) must be received by other backends, to cause
* them to reset their rd_targblock values, before they can safely access
* the table again.
*/
/*
* Drop free-space info for removed blocks; these must not get entered
* into the FSM!
*/
pageSpaces = vacrelstats->free_pages;
n = vacrelstats->num_free_pages;
j = 0;
for (i = 0; i < n; i++)
{
if (pageSpaces[i].blkno < new_rel_pages)
{
pageSpaces[j] = pageSpaces[i];
j++;
}
}
vacrelstats->num_free_pages = j;
/*
* If tot_free_pages was more than num_free_pages, we can't tell for sure
* what its correct value is now, because we don't know which of the
* forgotten pages are getting truncated. Conservatively set it equal to
* num_free_pages.
*/
vacrelstats->tot_free_pages = j;
/* We destroyed the heap ordering, so mark array unordered */
vacrelstats->fs_is_heap = false;
/* update statistics */
vacrelstats->rel_pages = new_rel_pages;
vacrelstats->pages_removed = old_rel_pages - new_rel_pages;
ereport(elevel,
(errmsg("\"%s\": truncated %u to %u pages",
RelationGetRelationName(onerel),
old_rel_pages, new_rel_pages),
errdetail("%s.",
pg_rusage_show(&ru0))));
}
Datum
ginvacuumcleanup(PG_FUNCTION_ARGS)
{
MIRROREDLOCK_BUFMGR_DECLARE;
IndexVacuumInfo *info = (IndexVacuumInfo *) PG_GETARG_POINTER(0);
IndexBulkDeleteResult *stats = (IndexBulkDeleteResult *) PG_GETARG_POINTER(1);
Relation index = info->index;
bool needLock;
BlockNumber npages,
blkno;
BlockNumber totFreePages,
nFreePages,
*freePages,
maxFreePages;
BlockNumber lastBlock = GIN_ROOT_BLKNO,
lastFilledBlock = GIN_ROOT_BLKNO;
/* Set up all-zero stats if ginbulkdelete wasn't called */
if (stats == NULL)
stats = (IndexBulkDeleteResult *) palloc0(sizeof(IndexBulkDeleteResult));
/*
* XXX we always report the heap tuple count as the number of index
* entries. This is bogus if the index is partial, but it's real hard to
* tell how many distinct heap entries are referenced by a GIN index.
*/
stats->num_index_tuples = info->num_heap_tuples;
/*
* If vacuum full, we already have exclusive lock on the index. Otherwise,
* need lock unless it's local to this backend.
*/
if (info->vacuum_full)
needLock = false;
else
needLock = !RELATION_IS_LOCAL(index);
if (needLock)
LockRelationForExtension(index, ExclusiveLock);
npages = RelationGetNumberOfBlocks(index);
if (needLock)
UnlockRelationForExtension(index, ExclusiveLock);
maxFreePages = npages;
if (maxFreePages > MaxFSMPages)
maxFreePages = MaxFSMPages;
totFreePages = nFreePages = 0;
freePages = (BlockNumber *) palloc(sizeof(BlockNumber) * maxFreePages);
for (blkno = GIN_ROOT_BLKNO + 1; blkno < npages; blkno++)
{
Buffer buffer;
Page page;
vacuum_delay_point();
// -------- MirroredLock ----------
MIRROREDLOCK_BUFMGR_LOCK;
buffer = ReadBuffer(index, blkno);
LockBuffer(buffer, GIN_SHARE);
page = (Page) BufferGetPage(buffer);
if (GinPageIsDeleted(page))
{
if (nFreePages < maxFreePages)
freePages[nFreePages++] = blkno;
totFreePages++;
}
else
lastFilledBlock = blkno;
UnlockReleaseBuffer(buffer);
MIRROREDLOCK_BUFMGR_UNLOCK;
// -------- MirroredLock ----------
}
lastBlock = npages - 1;
if (info->vacuum_full && nFreePages > 0)
{
/* try to truncate index */
int i;
for (i = 0; i < nFreePages; i++)
if (freePages[i] >= lastFilledBlock)
{
totFreePages = nFreePages = i;
break;
}
if (lastBlock > lastFilledBlock)
RelationTruncate(
index,
lastFilledBlock + 1,
/* markPersistentAsPhysicallyTruncated */ true);
stats->pages_removed = lastBlock - lastFilledBlock;
}
RecordIndexFreeSpace(&index->rd_node, totFreePages, nFreePages, freePages);
stats->pages_free = totFreePages;
if (needLock)
LockRelationForExtension(index, ExclusiveLock);
stats->num_pages = RelationGetNumberOfBlocks(index);
if (needLock)
UnlockRelationForExtension(index, ExclusiveLock);
PG_RETURN_POINTER(stats);
}
/*
* lazy_truncate_heap - try to truncate off any empty pages at the end
*/
static void
lazy_truncate_heap(Relation onerel, LVRelStats *vacrelstats)
{
BlockNumber old_rel_pages = vacrelstats->rel_pages;
BlockNumber new_rel_pages;
PGRUsage ru0;
int lock_retry;
pg_rusage_init(&ru0);
/*
* Loop until no more truncating can be done.
*/
do
{
/*
* We need full exclusive lock on the relation in order to do
* truncation. If we can't get it, give up rather than waiting --- we
* don't want to block other backends, and we don't want to deadlock
* (which is quite possible considering we already hold a lower-grade
* lock).
*/
vacrelstats->lock_waiter_detected = false;
lock_retry = 0;
while (true)
{
if (ConditionalLockRelation(onerel, AccessExclusiveLock))
break;
/*
* Check for interrupts while trying to (re-)acquire the exclusive
* lock.
*/
CHECK_FOR_INTERRUPTS();
if (++lock_retry > (AUTOVACUUM_TRUNCATE_LOCK_TIMEOUT /
AUTOVACUUM_TRUNCATE_LOCK_WAIT_INTERVAL))
{
/*
* We failed to establish the lock in the specified number of
* retries. This means we give up truncating. Suppress the
* ANALYZE step. Doing an ANALYZE at this point will reset the
* dead_tuple_count in the stats collector, so we will not get
* called by the autovacuum launcher again to do the truncate.
*/
vacrelstats->lock_waiter_detected = true;
ereport(LOG,
(errmsg("automatic vacuum of table \"%s.%s.%s\": "
"could not (re)acquire exclusive "
"lock for truncate scan",
get_database_name(MyDatabaseId),
get_namespace_name(RelationGetNamespace(onerel)),
RelationGetRelationName(onerel))));
return;
}
pg_usleep(AUTOVACUUM_TRUNCATE_LOCK_WAIT_INTERVAL);
}
/*
* Now that we have exclusive lock, look to see if the rel has grown
* whilst we were vacuuming with non-exclusive lock. If so, give up;
* the newly added pages presumably contain non-deletable tuples.
*/
new_rel_pages = RelationGetNumberOfBlocks(onerel);
if (new_rel_pages != old_rel_pages)
{
/*
* Note: we intentionally don't update vacrelstats->rel_pages with
* the new rel size here. If we did, it would amount to assuming
* that the new pages are empty, which is unlikely. Leaving the
* numbers alone amounts to assuming that the new pages have the
* same tuple density as existing ones, which is less unlikely.
*/
UnlockRelation(onerel, AccessExclusiveLock);
return;
}
/*
* Scan backwards from the end to verify that the end pages actually
* contain no tuples. This is *necessary*, not optional, because
* other backends could have added tuples to these pages whilst we
* were vacuuming.
*/
new_rel_pages = count_nondeletable_pages(onerel, vacrelstats);
if (new_rel_pages >= old_rel_pages)
{
/* can't do anything after all */
UnlockRelation(onerel, AccessExclusiveLock);
return;
}
/*
* Okay to truncate.
*/
RelationTruncate(onerel, new_rel_pages);
/*
* We can release the exclusive lock as soon as we have truncated.
* Other backends can't safely access the relation until they have
* processed the smgr invalidation that smgrtruncate sent out ... but
* that should happen as part of standard invalidation processing once
* they acquire lock on the relation.
*/
UnlockRelation(onerel, AccessExclusiveLock);
/*
* Update statistics. Here, it *is* correct to adjust rel_pages
* without also touching reltuples, since the tuple count wasn't
* changed by the truncation.
*/
vacrelstats->pages_removed += old_rel_pages - new_rel_pages;
vacrelstats->rel_pages = new_rel_pages;
ereport(elevel,
(errmsg("\"%s\": truncated %u to %u pages",
RelationGetRelationName(onerel),
old_rel_pages, new_rel_pages),
errdetail("%s.",
pg_rusage_show(&ru0))));
old_rel_pages = new_rel_pages;
} while (new_rel_pages > vacrelstats->nonempty_pages &&
vacrelstats->lock_waiter_detected);
}
/*
* lazy_truncate_heap - try to truncate off any empty pages at the end
*/
static void
lazy_truncate_heap(Relation onerel, LVRelStats *vacrelstats)
{
BlockNumber old_rel_pages = vacrelstats->rel_pages;
BlockNumber new_rel_pages;
PageFreeSpaceInfo *pageSpaces;
int n;
int i,
j;
PGRUsage ru0;
pg_rusage_init(&ru0);
/*
* We need full exclusive lock on the relation in order to do truncation.
* If we can't get it, give up rather than waiting --- we don't want to
* block other backends, and we don't want to deadlock (which is quite
* possible considering we already hold a lower-grade lock).
*/
if (!ConditionalLockRelation(onerel, AccessExclusiveLock))
return;
/*
* Now that we have exclusive lock, look to see if the rel has grown
* whilst we were vacuuming with non-exclusive lock. If so, give up; the
* newly added pages presumably contain non-deletable tuples.
*/
new_rel_pages = RelationGetNumberOfBlocks(onerel);
if (new_rel_pages != old_rel_pages)
{
/* might as well use the latest news when we update pg_class stats */
vacrelstats->rel_pages = new_rel_pages;
UnlockRelation(onerel, AccessExclusiveLock);
return;
}
/*
* Scan backwards from the end to verify that the end pages actually
* contain no tuples. This is *necessary*, not optional, because other
* backends could have added tuples to these pages whilst we were
* vacuuming.
*/
new_rel_pages = count_nondeletable_pages(onerel, vacrelstats);
if (new_rel_pages >= old_rel_pages)
{
/* can't do anything after all */
UnlockRelation(onerel, AccessExclusiveLock);
return;
}
/*
* Okay to truncate.
*/
RelationTruncate(
onerel,
new_rel_pages,
/* markPersistentAsPhysicallyTruncated */ true);
/*
* Drop free-space info for removed blocks; these must not get entered
* into the FSM!
*/
pageSpaces = vacrelstats->free_pages;
n = vacrelstats->num_free_pages;
j = 0;
for (i = 0; i < n; i++)
{
if (pageSpaces[i].blkno < new_rel_pages)
{
pageSpaces[j] = pageSpaces[i];
j++;
}
}
vacrelstats->num_free_pages = j;
/*
* If tot_free_pages was more than num_free_pages, we can't tell for sure
* what its correct value is now, because we don't know which of the
* forgotten pages are getting truncated. Conservatively set it equal to
* num_free_pages.
*/
vacrelstats->tot_free_pages = j;
/* We destroyed the heap ordering, so mark array unordered */
vacrelstats->fs_is_heap = false;
/* update statistics */
vacrelstats->rel_pages = new_rel_pages;
vacrelstats->pages_removed = old_rel_pages - new_rel_pages;
/*
* We can't keep the exclusive lock until commit, since this will cause
* deadlock, see MPP-5733.
*/
UnlockRelation(onerel, AccessExclusiveLock);
ereport(elevel,
(errmsg("\"%s\": truncated %u to %u pages",
RelationGetRelationName(onerel),
old_rel_pages, new_rel_pages),
errdetail("%s.",
pg_rusage_show(&ru0))));
}
