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postgres/src/backend/access/spgist/spgvacuum.c

959 lines
26 KiB

/*-------------------------------------------------------------------------
*
* spgvacuum.c
* vacuum for SP-GiST
*
*
* Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/access/spgist/spgvacuum.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/genam.h"
#include "access/spgist_private.h"
#include "access/transam.h"
#include "access/xloginsert.h"
#include "catalog/storage_xlog.h"
#include "commands/vacuum.h"
#include "miscadmin.h"
#include "storage/bufmgr.h"
#include "storage/indexfsm.h"
#include "storage/lmgr.h"
#include "utils/snapmgr.h"
/* Entry in pending-list of TIDs we need to revisit */
typedef struct spgVacPendingItem
{
ItemPointerData tid; /* redirection target to visit */
bool done; /* have we dealt with this? */
struct spgVacPendingItem *next; /* list link */
} spgVacPendingItem;
/* Local state for vacuum operations */
typedef struct spgBulkDeleteState
{
/* Parameters passed in to spgvacuumscan */
IndexVacuumInfo *info;
IndexBulkDeleteResult *stats;
IndexBulkDeleteCallback callback;
void *callback_state;
/* Additional working state */
SpGistState spgstate; /* for SPGiST operations that need one */
spgVacPendingItem *pendingList; /* TIDs we need to (re)visit */
TransactionId myXmin; /* for detecting newly-added redirects */
BlockNumber lastFilledBlock; /* last non-deletable block */
} spgBulkDeleteState;
/*
* Add TID to pendingList, but only if not already present.
*
* Note that new items are always appended at the end of the list; this
* ensures that scans of the list don't miss items added during the scan.
*/
static void
spgAddPendingTID(spgBulkDeleteState *bds, ItemPointer tid)
{
spgVacPendingItem *pitem;
spgVacPendingItem **listLink;
/* search the list for pre-existing entry */
listLink = &bds->pendingList;
while (*listLink != NULL)
{
pitem = *listLink;
if (ItemPointerEquals(tid, &pitem->tid))
return; /* already in list, do nothing */
listLink = &pitem->next;
}
/* not there, so append new entry */
pitem = (spgVacPendingItem *) palloc(sizeof(spgVacPendingItem));
pitem->tid = *tid;
pitem->done = false;
pitem->next = NULL;
*listLink = pitem;
}
/*
* Clear pendingList
*/
static void
spgClearPendingList(spgBulkDeleteState *bds)
{
spgVacPendingItem *pitem;
spgVacPendingItem *nitem;
for (pitem = bds->pendingList; pitem != NULL; pitem = nitem)
{
nitem = pitem->next;
/* All items in list should have been dealt with */
Assert(pitem->done);
pfree(pitem);
}
bds->pendingList = NULL;
}
/*
* Vacuum a regular (non-root) leaf page
*
* We must delete tuples that are targeted for deletion by the VACUUM,
* but not move any tuples that are referenced by outside links; we assume
* those are the ones that are heads of chains.
*
* If we find a REDIRECT that was made by a concurrently-running transaction,
* we must add its target TID to pendingList. (We don't try to visit the
* target immediately, first because we don't want VACUUM locking more than
* one buffer at a time, and second because the duplicate-filtering logic
* in spgAddPendingTID is useful to ensure we can't get caught in an infinite
* loop in the face of continuous concurrent insertions.)
*
* If forPending is true, we are examining the page as a consequence of
* chasing a redirect link, not as part of the normal sequential scan.
* We still vacuum the page normally, but we don't increment the stats
* about live tuples; else we'd double-count those tuples, since the page
* has been or will be visited in the sequential scan as well.
*/
static void
vacuumLeafPage(spgBulkDeleteState *bds, Relation index, Buffer buffer,
bool forPending)
{
Page page = BufferGetPage(buffer);
spgxlogVacuumLeaf xlrec;
OffsetNumber toDead[MaxIndexTuplesPerPage];
OffsetNumber toPlaceholder[MaxIndexTuplesPerPage];
OffsetNumber moveSrc[MaxIndexTuplesPerPage];
OffsetNumber moveDest[MaxIndexTuplesPerPage];
OffsetNumber chainSrc[MaxIndexTuplesPerPage];
OffsetNumber chainDest[MaxIndexTuplesPerPage];
OffsetNumber predecessor[MaxIndexTuplesPerPage + 1];
bool deletable[MaxIndexTuplesPerPage + 1];
int nDeletable;
OffsetNumber i,
max = PageGetMaxOffsetNumber(page);
memset(predecessor, 0, sizeof(predecessor));
memset(deletable, 0, sizeof(deletable));
nDeletable = 0;
/* Scan page, identify tuples to delete, accumulate stats */
for (i = FirstOffsetNumber; i <= max; i++)
{
SpGistLeafTuple lt;
lt = (SpGistLeafTuple) PageGetItem(page,
PageGetItemId(page, i));
if (lt->tupstate == SPGIST_LIVE)
{
Assert(ItemPointerIsValid(&lt->heapPtr));
if (bds->callback(&lt->heapPtr, bds->callback_state))
{
bds->stats->tuples_removed += 1;
deletable[i] = true;
nDeletable++;
}
else
{
if (!forPending)
bds->stats->num_index_tuples += 1;
}
/* Form predecessor map, too */
if (lt->nextOffset != InvalidOffsetNumber)
{
/* paranoia about corrupted chain links */
if (lt->nextOffset < FirstOffsetNumber ||
lt->nextOffset > max ||
predecessor[lt->nextOffset] != InvalidOffsetNumber)
elog(ERROR, "inconsistent tuple chain links in page %u of index \"%s\"",
BufferGetBlockNumber(buffer),
RelationGetRelationName(index));
predecessor[lt->nextOffset] = i;
}
}
else if (lt->tupstate == SPGIST_REDIRECT)
{
SpGistDeadTuple dt = (SpGistDeadTuple) lt;
Assert(dt->nextOffset == InvalidOffsetNumber);
Assert(ItemPointerIsValid(&dt->pointer));
/*
* Add target TID to pending list if the redirection could have
* happened since VACUUM started.
*
* Note: we could make a tighter test by seeing if the xid is
* "running" according to the active snapshot; but tqual.c doesn't
* currently export a suitable API, and it's not entirely clear
* that a tighter test is worth the cycles anyway.
*/
if (TransactionIdFollowsOrEquals(dt->xid, bds->myXmin))
spgAddPendingTID(bds, &dt->pointer);
}
else
{
Assert(lt->nextOffset == InvalidOffsetNumber);
}
}
if (nDeletable == 0)
return; /* nothing more to do */
/*----------
* Figure out exactly what we have to do. We do this separately from
* actually modifying the page, mainly so that we have a representation
* that can be dumped into WAL and then the replay code can do exactly
* the same thing. The output of this step consists of six arrays
* describing four kinds of operations, to be performed in this order:
*
* toDead[]: tuple numbers to be replaced with DEAD tuples
* toPlaceholder[]: tuple numbers to be replaced with PLACEHOLDER tuples
* moveSrc[]: tuple numbers that need to be relocated to another offset
* (replacing the tuple there) and then replaced with PLACEHOLDER tuples
* moveDest[]: new locations for moveSrc tuples
* chainSrc[]: tuple numbers whose chain links (nextOffset) need updates
* chainDest[]: new values of nextOffset for chainSrc members
*
* It's easiest to figure out what we have to do by processing tuple
* chains, so we iterate over all the tuples (not just the deletable
* ones!) to identify chain heads, then chase down each chain and make
* work item entries for deletable tuples within the chain.
*----------
*/
xlrec.nDead = xlrec.nPlaceholder = xlrec.nMove = xlrec.nChain = 0;
for (i = FirstOffsetNumber; i <= max; i++)
{
SpGistLeafTuple head;
bool interveningDeletable;
OffsetNumber prevLive;
OffsetNumber j;
head = (SpGistLeafTuple) PageGetItem(page,
PageGetItemId(page, i));
if (head->tupstate != SPGIST_LIVE)
continue; /* can't be a chain member */
if (predecessor[i] != 0)
continue; /* not a chain head */
/* initialize ... */
interveningDeletable = false;
prevLive = deletable[i] ? InvalidOffsetNumber : i;
/* scan down the chain ... */
j = head->nextOffset;
while (j != InvalidOffsetNumber)
{
SpGistLeafTuple lt;
lt = (SpGistLeafTuple) PageGetItem(page,
PageGetItemId(page, j));
if (lt->tupstate != SPGIST_LIVE)
{
/* all tuples in chain should be live */
elog(ERROR, "unexpected SPGiST tuple state: %d",
lt->tupstate);
}
if (deletable[j])
{
/* This tuple should be replaced by a placeholder */
toPlaceholder[xlrec.nPlaceholder] = j;
xlrec.nPlaceholder++;
/* previous live tuple's chain link will need an update */
interveningDeletable = true;
}
else if (prevLive == InvalidOffsetNumber)
{
/*
* This is the first live tuple in the chain. It has to move
* to the head position.
*/
moveSrc[xlrec.nMove] = j;
moveDest[xlrec.nMove] = i;
xlrec.nMove++;
/* Chain updates will be applied after the move */
prevLive = i;
interveningDeletable = false;
}
else
{
/*
* Second or later live tuple. Arrange to re-chain it to the
* previous live one, if there was a gap.
*/
if (interveningDeletable)
{
chainSrc[xlrec.nChain] = prevLive;
chainDest[xlrec.nChain] = j;
xlrec.nChain++;
}
prevLive = j;
interveningDeletable = false;
}
j = lt->nextOffset;
}
if (prevLive == InvalidOffsetNumber)
{
/* The chain is entirely removable, so we need a DEAD tuple */
toDead[xlrec.nDead] = i;
xlrec.nDead++;
}
else if (interveningDeletable)
{
/* One or more deletions at end of chain, so close it off */
chainSrc[xlrec.nChain] = prevLive;
chainDest[xlrec.nChain] = InvalidOffsetNumber;
xlrec.nChain++;
}
}
/* sanity check ... */
if (nDeletable != xlrec.nDead + xlrec.nPlaceholder + xlrec.nMove)
elog(ERROR, "inconsistent counts of deletable tuples");
/* Do the updates */
START_CRIT_SECTION();
spgPageIndexMultiDelete(&bds->spgstate, page,
toDead, xlrec.nDead,
SPGIST_DEAD, SPGIST_DEAD,
InvalidBlockNumber, InvalidOffsetNumber);
spgPageIndexMultiDelete(&bds->spgstate, page,
toPlaceholder, xlrec.nPlaceholder,
SPGIST_PLACEHOLDER, SPGIST_PLACEHOLDER,
InvalidBlockNumber, InvalidOffsetNumber);
/*
* We implement the move step by swapping the item pointers of the source
* and target tuples, then replacing the newly-source tuples with
* placeholders. This is perhaps unduly friendly with the page data
* representation, but it's fast and doesn't risk page overflow when a
* tuple to be relocated is large.
*/
for (i = 0; i < xlrec.nMove; i++)
{
ItemId idSrc = PageGetItemId(page, moveSrc[i]);
ItemId idDest = PageGetItemId(page, moveDest[i]);
ItemIdData tmp;
tmp = *idSrc;
*idSrc = *idDest;
*idDest = tmp;
}
spgPageIndexMultiDelete(&bds->spgstate, page,
moveSrc, xlrec.nMove,
SPGIST_PLACEHOLDER, SPGIST_PLACEHOLDER,
InvalidBlockNumber, InvalidOffsetNumber);
for (i = 0; i < xlrec.nChain; i++)
{
SpGistLeafTuple lt;
lt = (SpGistLeafTuple) PageGetItem(page,
PageGetItemId(page, chainSrc[i]));
Assert(lt->tupstate == SPGIST_LIVE);
lt->nextOffset = chainDest[i];
}
MarkBufferDirty(buffer);
if (RelationNeedsWAL(index))
{
XLogRecPtr recptr;
Revamp the WAL record format. Each WAL record now carries information about the modified relation and block(s) in a standardized format. That makes it easier to write tools that need that information, like pg_rewind, prefetching the blocks to speed up recovery, etc. There's a whole new API for building WAL records, replacing the XLogRecData chains used previously. The new API consists of XLogRegister* functions, which are called for each buffer and chunk of data that is added to the record. The new API also gives more control over when a full-page image is written, by passing flags to the XLogRegisterBuffer function. This also simplifies the XLogReadBufferForRedo() calls. The function can dig the relation and block number from the WAL record, so they no longer need to be passed as arguments. For the convenience of redo routines, XLogReader now disects each WAL record after reading it, copying the main data part and the per-block data into MAXALIGNed buffers. The data chunks are not aligned within the WAL record, but the redo routines can assume that the pointers returned by XLogRecGet* functions are. Redo routines are now passed the XLogReaderState, which contains the record in the already-disected format, instead of the plain XLogRecord. The new record format also makes the fixed size XLogRecord header smaller, by removing the xl_len field. The length of the "main data" portion is now stored at the end of the WAL record, and there's a separate header after XLogRecord for it. The alignment padding at the end of XLogRecord is also removed. This compansates for the fact that the new format would otherwise be more bulky than the old format. Reviewed by Andres Freund, Amit Kapila, Michael Paquier, Alvaro Herrera, Fujii Masao.
11 years ago
XLogBeginInsert();
STORE_STATE(&bds->spgstate, xlrec.stateSrc);
XLogRegisterData((char *) &xlrec, SizeOfSpgxlogVacuumLeaf);
/* sizeof(xlrec) should be a multiple of sizeof(OffsetNumber) */
XLogRegisterData((char *) toDead, sizeof(OffsetNumber) * xlrec.nDead);
XLogRegisterData((char *) toPlaceholder, sizeof(OffsetNumber) * xlrec.nPlaceholder);
XLogRegisterData((char *) moveSrc, sizeof(OffsetNumber) * xlrec.nMove);
XLogRegisterData((char *) moveDest, sizeof(OffsetNumber) * xlrec.nMove);
XLogRegisterData((char *) chainSrc, sizeof(OffsetNumber) * xlrec.nChain);
XLogRegisterData((char *) chainDest, sizeof(OffsetNumber) * xlrec.nChain);
XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
recptr = XLogInsert(RM_SPGIST_ID, XLOG_SPGIST_VACUUM_LEAF);
PageSetLSN(page, recptr);
}
END_CRIT_SECTION();
}
/*
* Vacuum a root page when it is also a leaf
*
* On the root, we just delete any dead leaf tuples; no fancy business
*/
static void
vacuumLeafRoot(spgBulkDeleteState *bds, Relation index, Buffer buffer)
{
Page page = BufferGetPage(buffer);
spgxlogVacuumRoot xlrec;
OffsetNumber toDelete[MaxIndexTuplesPerPage];
OffsetNumber i,
max = PageGetMaxOffsetNumber(page);
xlrec.nDelete = 0;
/* Scan page, identify tuples to delete, accumulate stats */
for (i = FirstOffsetNumber; i <= max; i++)
{
SpGistLeafTuple lt;
lt = (SpGistLeafTuple) PageGetItem(page,
PageGetItemId(page, i));
if (lt->tupstate == SPGIST_LIVE)
{
Assert(ItemPointerIsValid(&lt->heapPtr));
if (bds->callback(&lt->heapPtr, bds->callback_state))
{
bds->stats->tuples_removed += 1;
toDelete[xlrec.nDelete] = i;
xlrec.nDelete++;
}
else
{
bds->stats->num_index_tuples += 1;
}
}
else
{
/* all tuples on root should be live */
elog(ERROR, "unexpected SPGiST tuple state: %d",
lt->tupstate);
}
}
if (xlrec.nDelete == 0)
return; /* nothing more to do */
/* Do the update */
START_CRIT_SECTION();
/* The tuple numbers are in order, so we can use PageIndexMultiDelete */
PageIndexMultiDelete(page, toDelete, xlrec.nDelete);
MarkBufferDirty(buffer);
if (RelationNeedsWAL(index))
{
XLogRecPtr recptr;
Revamp the WAL record format. Each WAL record now carries information about the modified relation and block(s) in a standardized format. That makes it easier to write tools that need that information, like pg_rewind, prefetching the blocks to speed up recovery, etc. There's a whole new API for building WAL records, replacing the XLogRecData chains used previously. The new API consists of XLogRegister* functions, which are called for each buffer and chunk of data that is added to the record. The new API also gives more control over when a full-page image is written, by passing flags to the XLogRegisterBuffer function. This also simplifies the XLogReadBufferForRedo() calls. The function can dig the relation and block number from the WAL record, so they no longer need to be passed as arguments. For the convenience of redo routines, XLogReader now disects each WAL record after reading it, copying the main data part and the per-block data into MAXALIGNed buffers. The data chunks are not aligned within the WAL record, but the redo routines can assume that the pointers returned by XLogRecGet* functions are. Redo routines are now passed the XLogReaderState, which contains the record in the already-disected format, instead of the plain XLogRecord. The new record format also makes the fixed size XLogRecord header smaller, by removing the xl_len field. The length of the "main data" portion is now stored at the end of the WAL record, and there's a separate header after XLogRecord for it. The alignment padding at the end of XLogRecord is also removed. This compansates for the fact that the new format would otherwise be more bulky than the old format. Reviewed by Andres Freund, Amit Kapila, Michael Paquier, Alvaro Herrera, Fujii Masao.
11 years ago
XLogBeginInsert();
/* Prepare WAL record */
STORE_STATE(&bds->spgstate, xlrec.stateSrc);
XLogRegisterData((char *) &xlrec, SizeOfSpgxlogVacuumRoot);
/* sizeof(xlrec) should be a multiple of sizeof(OffsetNumber) */
XLogRegisterData((char *) toDelete,
sizeof(OffsetNumber) * xlrec.nDelete);
XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
recptr = XLogInsert(RM_SPGIST_ID, XLOG_SPGIST_VACUUM_ROOT);
PageSetLSN(page, recptr);
}
END_CRIT_SECTION();
}
/*
* Clean up redirect and placeholder tuples on the given page
*
* Redirect tuples can be marked placeholder once they're old enough.
* Placeholder tuples can be removed if it won't change the offsets of
* non-placeholder ones.
*
* Unlike the routines above, this works on both leaf and inner pages.
*/
static void
vacuumRedirectAndPlaceholder(Relation index, Buffer buffer)
{
Page page = BufferGetPage(buffer);
SpGistPageOpaque opaque = SpGistPageGetOpaque(page);
OffsetNumber i,
max = PageGetMaxOffsetNumber(page),
firstPlaceholder = InvalidOffsetNumber;
bool hasNonPlaceholder = false;
bool hasUpdate = false;
OffsetNumber itemToPlaceholder[MaxIndexTuplesPerPage];
OffsetNumber itemnos[MaxIndexTuplesPerPage];
spgxlogVacuumRedirect xlrec;
xlrec.nToPlaceholder = 0;
xlrec.newestRedirectXid = InvalidTransactionId;
START_CRIT_SECTION();
/*
* Scan backwards to convert old redirection tuples to placeholder tuples,
* and identify location of last non-placeholder tuple while at it.
*/
for (i = max;
i >= FirstOffsetNumber &&
(opaque->nRedirection > 0 || !hasNonPlaceholder);
i--)
{
SpGistDeadTuple dt;
dt = (SpGistDeadTuple) PageGetItem(page, PageGetItemId(page, i));
if (dt->tupstate == SPGIST_REDIRECT &&
TransactionIdPrecedes(dt->xid, RecentGlobalXmin))
{
dt->tupstate = SPGIST_PLACEHOLDER;
Assert(opaque->nRedirection > 0);
opaque->nRedirection--;
opaque->nPlaceholder++;
/* remember newest XID among the removed redirects */
if (!TransactionIdIsValid(xlrec.newestRedirectXid) ||
TransactionIdPrecedes(xlrec.newestRedirectXid, dt->xid))
xlrec.newestRedirectXid = dt->xid;
ItemPointerSetInvalid(&dt->pointer);
itemToPlaceholder[xlrec.nToPlaceholder] = i;
xlrec.nToPlaceholder++;
hasUpdate = true;
}
if (dt->tupstate == SPGIST_PLACEHOLDER)
{
if (!hasNonPlaceholder)
firstPlaceholder = i;
}
else
{
hasNonPlaceholder = true;
}
}
/*
* Any placeholder tuples at the end of page can safely be removed. We
* can't remove ones before the last non-placeholder, though, because we
* can't alter the offset numbers of non-placeholder tuples.
*/
if (firstPlaceholder != InvalidOffsetNumber)
{
/*
* We do not store this array to rdata because it's easy to recreate.
*/
for (i = firstPlaceholder; i <= max; i++)
itemnos[i - firstPlaceholder] = i;
i = max - firstPlaceholder + 1;
Assert(opaque->nPlaceholder >= i);
opaque->nPlaceholder -= i;
/* The array is surely sorted, so can use PageIndexMultiDelete */
PageIndexMultiDelete(page, itemnos, i);
hasUpdate = true;
}
xlrec.firstPlaceholder = firstPlaceholder;
if (hasUpdate)
MarkBufferDirty(buffer);
if (hasUpdate && RelationNeedsWAL(index))
{
XLogRecPtr recptr;
Revamp the WAL record format. Each WAL record now carries information about the modified relation and block(s) in a standardized format. That makes it easier to write tools that need that information, like pg_rewind, prefetching the blocks to speed up recovery, etc. There's a whole new API for building WAL records, replacing the XLogRecData chains used previously. The new API consists of XLogRegister* functions, which are called for each buffer and chunk of data that is added to the record. The new API also gives more control over when a full-page image is written, by passing flags to the XLogRegisterBuffer function. This also simplifies the XLogReadBufferForRedo() calls. The function can dig the relation and block number from the WAL record, so they no longer need to be passed as arguments. For the convenience of redo routines, XLogReader now disects each WAL record after reading it, copying the main data part and the per-block data into MAXALIGNed buffers. The data chunks are not aligned within the WAL record, but the redo routines can assume that the pointers returned by XLogRecGet* functions are. Redo routines are now passed the XLogReaderState, which contains the record in the already-disected format, instead of the plain XLogRecord. The new record format also makes the fixed size XLogRecord header smaller, by removing the xl_len field. The length of the "main data" portion is now stored at the end of the WAL record, and there's a separate header after XLogRecord for it. The alignment padding at the end of XLogRecord is also removed. This compansates for the fact that the new format would otherwise be more bulky than the old format. Reviewed by Andres Freund, Amit Kapila, Michael Paquier, Alvaro Herrera, Fujii Masao.
11 years ago
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfSpgxlogVacuumRedirect);
XLogRegisterData((char *) itemToPlaceholder,
sizeof(OffsetNumber) * xlrec.nToPlaceholder);
XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
Revamp the WAL record format. Each WAL record now carries information about the modified relation and block(s) in a standardized format. That makes it easier to write tools that need that information, like pg_rewind, prefetching the blocks to speed up recovery, etc. There's a whole new API for building WAL records, replacing the XLogRecData chains used previously. The new API consists of XLogRegister* functions, which are called for each buffer and chunk of data that is added to the record. The new API also gives more control over when a full-page image is written, by passing flags to the XLogRegisterBuffer function. This also simplifies the XLogReadBufferForRedo() calls. The function can dig the relation and block number from the WAL record, so they no longer need to be passed as arguments. For the convenience of redo routines, XLogReader now disects each WAL record after reading it, copying the main data part and the per-block data into MAXALIGNed buffers. The data chunks are not aligned within the WAL record, but the redo routines can assume that the pointers returned by XLogRecGet* functions are. Redo routines are now passed the XLogReaderState, which contains the record in the already-disected format, instead of the plain XLogRecord. The new record format also makes the fixed size XLogRecord header smaller, by removing the xl_len field. The length of the "main data" portion is now stored at the end of the WAL record, and there's a separate header after XLogRecord for it. The alignment padding at the end of XLogRecord is also removed. This compansates for the fact that the new format would otherwise be more bulky than the old format. Reviewed by Andres Freund, Amit Kapila, Michael Paquier, Alvaro Herrera, Fujii Masao.
11 years ago
recptr = XLogInsert(RM_SPGIST_ID, XLOG_SPGIST_VACUUM_REDIRECT);
PageSetLSN(page, recptr);
}
END_CRIT_SECTION();
}
/*
* Process one page during a bulkdelete scan
*/
static void
spgvacuumpage(spgBulkDeleteState *bds, BlockNumber blkno)
{
Relation index = bds->info->index;
Buffer buffer;
Page page;
/* call vacuum_delay_point while not holding any buffer lock */
vacuum_delay_point();
buffer = ReadBufferExtended(index, MAIN_FORKNUM, blkno,
RBM_NORMAL, bds->info->strategy);
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
page = (Page) BufferGetPage(buffer);
if (PageIsNew(page))
{
/*
* We found an all-zero page, which could happen if the database
* crashed just after extending the file. Recycle it.
*/
}
else if (PageIsEmpty(page))
{
/* nothing to do */
}
else if (SpGistPageIsLeaf(page))
{
if (SpGistBlockIsRoot(blkno))
{
vacuumLeafRoot(bds, index, buffer);
/* no need for vacuumRedirectAndPlaceholder */
}
else
{
vacuumLeafPage(bds, index, buffer, false);
vacuumRedirectAndPlaceholder(index, buffer);
}
}
else
{
/* inner page */
vacuumRedirectAndPlaceholder(index, buffer);
}
/*
* The root pages must never be deleted, nor marked as available in FSM,
* because we don't want them ever returned by a search for a place to put
* a new tuple. Otherwise, check for empty page, and make sure the FSM
* knows about it.
*/
if (!SpGistBlockIsRoot(blkno))
{
if (PageIsNew(page) || PageIsEmpty(page))
{
RecordFreeIndexPage(index, blkno);
bds->stats->pages_deleted++;
}
else
{
SpGistSetLastUsedPage(index, buffer);
bds->lastFilledBlock = blkno;
}
}
UnlockReleaseBuffer(buffer);
}
/*
* Process the pending-TID list between pages of the main scan
*/
static void
spgprocesspending(spgBulkDeleteState *bds)
{
Relation index = bds->info->index;
spgVacPendingItem *pitem;
spgVacPendingItem *nitem;
BlockNumber blkno;
Buffer buffer;
Page page;
for (pitem = bds->pendingList; pitem != NULL; pitem = pitem->next)
{
if (pitem->done)
continue; /* ignore already-done items */
/* call vacuum_delay_point while not holding any buffer lock */
vacuum_delay_point();
/* examine the referenced page */
blkno = ItemPointerGetBlockNumber(&pitem->tid);
buffer = ReadBufferExtended(index, MAIN_FORKNUM, blkno,
RBM_NORMAL, bds->info->strategy);
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
page = (Page) BufferGetPage(buffer);
if (PageIsNew(page) || SpGistPageIsDeleted(page))
{
/* Probably shouldn't happen, but ignore it */
}
else if (SpGistPageIsLeaf(page))
{
if (SpGistBlockIsRoot(blkno))
{
/* this should definitely not happen */
elog(ERROR, "redirection leads to root page of index \"%s\"",
RelationGetRelationName(index));
}
/* deal with any deletable tuples */
vacuumLeafPage(bds, index, buffer, true);
/* might as well do this while we are here */
vacuumRedirectAndPlaceholder(index, buffer);
SpGistSetLastUsedPage(index, buffer);
/*
* We can mark as done not only this item, but any later ones
* pointing at the same page, since we vacuumed the whole page.
*/
pitem->done = true;
for (nitem = pitem->next; nitem != NULL; nitem = nitem->next)
{
if (ItemPointerGetBlockNumber(&nitem->tid) == blkno)
nitem->done = true;
}
}
else
{
/*
* On an inner page, visit the referenced inner tuple and add all
* its downlinks to the pending list. We might have pending items
* for more than one inner tuple on the same page (in fact this is
* pretty likely given the way space allocation works), so get
* them all while we are here.
*/
for (nitem = pitem; nitem != NULL; nitem = nitem->next)
{
if (nitem->done)
continue;
if (ItemPointerGetBlockNumber(&nitem->tid) == blkno)
{
OffsetNumber offset;
SpGistInnerTuple innerTuple;
offset = ItemPointerGetOffsetNumber(&nitem->tid);
innerTuple = (SpGistInnerTuple) PageGetItem(page,
PageGetItemId(page, offset));
if (innerTuple->tupstate == SPGIST_LIVE)
{
SpGistNodeTuple node;
int i;
SGITITERATE(innerTuple, i, node)
{
if (ItemPointerIsValid(&node->t_tid))
spgAddPendingTID(bds, &node->t_tid);
}
}
else if (innerTuple->tupstate == SPGIST_REDIRECT)
{
/* transfer attention to redirect point */
spgAddPendingTID(bds,
&((SpGistDeadTuple) innerTuple)->pointer);
}
else
elog(ERROR, "unexpected SPGiST tuple state: %d",
innerTuple->tupstate);
nitem->done = true;
}
}
}
UnlockReleaseBuffer(buffer);
}
spgClearPendingList(bds);
}
/*
* Perform a bulkdelete scan
*/
static void
spgvacuumscan(spgBulkDeleteState *bds)
{
Relation index = bds->info->index;
bool needLock;
BlockNumber num_pages,
blkno;
/* Finish setting up spgBulkDeleteState */
initSpGistState(&bds->spgstate, index);
bds->pendingList = NULL;
bds->myXmin = GetActiveSnapshot()->xmin;
bds->lastFilledBlock = SPGIST_LAST_FIXED_BLKNO;
/*
* Reset counts that will be incremented during the scan; needed in case
* of multiple scans during a single VACUUM command
*/
bds->stats->estimated_count = false;
bds->stats->num_index_tuples = 0;
bds->stats->pages_deleted = 0;
/* We can skip locking for new or temp relations */
needLock = !RELATION_IS_LOCAL(index);
/*
* 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. See more extensive comments about this
* in btvacuumscan().
*/
blkno = SPGIST_METAPAGE_BLKNO + 1;
for (;;)
{
/* Get the current relation length */
if (needLock)
LockRelationForExtension(index, ExclusiveLock);
num_pages = RelationGetNumberOfBlocks(index);
if (needLock)
UnlockRelationForExtension(index, ExclusiveLock);
/* 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++)
{
spgvacuumpage(bds, blkno);
/* empty the pending-list after each page */
if (bds->pendingList != NULL)
spgprocesspending(bds);
}
}
/* Propagate local lastUsedPage cache to metablock */
SpGistUpdateMetaPage(index);
/*
* Truncate index if possible
*
* XXX disabled because it's unsafe due to possible concurrent inserts.
* We'd have to rescan the pages to make sure they're still empty, and it
* doesn't seem worth it. Note that btree doesn't do this either.
*
* Another reason not to truncate is that it could invalidate the cached
* pages-with-freespace pointers in the metapage and other backends'
* relation caches, that is leave them pointing to nonexistent pages.
* Adding RelationGetNumberOfBlocks calls to protect the places that use
* those pointers would be unduly expensive.
*/
#ifdef NOT_USED
if (num_pages > bds->lastFilledBlock + 1)
{
BlockNumber lastBlock = num_pages - 1;
num_pages = bds->lastFilledBlock + 1;
RelationTruncate(index, num_pages);
bds->stats->pages_removed += lastBlock - bds->lastFilledBlock;
bds->stats->pages_deleted -= lastBlock - bds->lastFilledBlock;
}
#endif
/* Report final stats */
bds->stats->num_pages = num_pages;
bds->stats->pages_free = bds->stats->pages_deleted;
}
/*
* Bulk deletion of all index entries pointing to a set of heap tuples.
* The set of target tuples is specified via a callback routine that tells
* whether any given heap tuple (identified by ItemPointer) is being deleted.
*
* Result: a palloc'd struct containing statistical info for VACUUM displays.
*/
IndexBulkDeleteResult *
spgbulkdelete(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
IndexBulkDeleteCallback callback, void *callback_state)
{
spgBulkDeleteState bds;
/* allocate stats if first time through, else re-use existing struct */
if (stats == NULL)
stats = (IndexBulkDeleteResult *) palloc0(sizeof(IndexBulkDeleteResult));
bds.info = info;
bds.stats = stats;
bds.callback = callback;
bds.callback_state = callback_state;
spgvacuumscan(&bds);
return stats;
}
/* Dummy callback to delete no tuples during spgvacuumcleanup */
static bool
dummy_callback(ItemPointer itemptr, void *state)
{
return false;
}
/*
* Post-VACUUM cleanup.
*
* Result: a palloc'd struct containing statistical info for VACUUM displays.
*/
IndexBulkDeleteResult *
spgvacuumcleanup(IndexVacuumInfo *info, IndexBulkDeleteResult *stats)
{
Relation index = info->index;
spgBulkDeleteState bds;
/* No-op in ANALYZE ONLY mode */
if (info->analyze_only)
return stats;
/*
* We don't need to scan the index if there was a preceding bulkdelete
* pass. Otherwise, make a pass that won't delete any live tuples, but
* might still accomplish useful stuff with redirect/placeholder cleanup,
* and in any case will provide stats.
*/
if (stats == NULL)
{
stats = (IndexBulkDeleteResult *) palloc0(sizeof(IndexBulkDeleteResult));
bds.info = info;
bds.stats = stats;
bds.callback = dummy_callback;
bds.callback_state = NULL;
spgvacuumscan(&bds);
}
/* Finally, vacuum the FSM */
IndexFreeSpaceMapVacuum(index);
/*
* It's quite possible for us to be fooled by concurrent tuple moves into
* double-counting some index tuples, so disbelieve any total that exceeds
* the underlying heap's count ... if we know that accurately. Otherwise
* this might just make matters worse.
*/
if (!info->estimated_count)
{
if (stats->num_index_tuples > info->num_heap_tuples)
stats->num_index_tuples = info->num_heap_tuples;
}
return stats;
}