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The reverted changes were intended to force a choice of whether any newly-added BufferGetPage() calls needed to be accompanied by a test of the snapshot age, to support the "snapshot too old" feature. Such an accompanying test is needed in about 7% of the cases, where the page is being used as part of a scan rather than positioning for other purposes (such as DML or vacuuming). The additional effort required for back-patching, and the doubt whether the intended benefit would really be there, have indicated it is best just to rely on developers to do the right thing based on comments and existing usage, as we do with many other conventions. This change should have little or no effect on generated executable code. Motivated by the back-patching pain of Tom Lane and Robert Haas
219 lines
5.4 KiB
C
219 lines
5.4 KiB
C
/*-------------------------------------------------------------------------
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*
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* blvacuum.c
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* Bloom VACUUM functions.
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*
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* Copyright (c) 2016, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* contrib/bloom/blvacuum.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/genam.h"
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#include "catalog/storage.h"
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#include "commands/vacuum.h"
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#include "miscadmin.h"
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#include "postmaster/autovacuum.h"
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#include "storage/bufmgr.h"
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#include "storage/indexfsm.h"
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#include "storage/lmgr.h"
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#include "bloom.h"
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/*
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* Bulk deletion of all index entries pointing to a set of heap tuples.
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* The set of target tuples is specified via a callback routine that tells
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* whether any given heap tuple (identified by ItemPointer) is being deleted.
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*
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* Result: a palloc'd struct containing statistical info for VACUUM displays.
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*/
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IndexBulkDeleteResult *
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blbulkdelete(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
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IndexBulkDeleteCallback callback, void *callback_state)
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{
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Relation index = info->index;
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BlockNumber blkno,
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npages;
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FreeBlockNumberArray notFullPage;
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int countPage = 0;
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BloomState state;
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Buffer buffer;
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Page page;
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GenericXLogState *gxlogState;
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if (stats == NULL)
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stats = (IndexBulkDeleteResult *) palloc0(sizeof(IndexBulkDeleteResult));
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initBloomState(&state, index);
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/*
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* Interate over the pages. We don't care about concurrently added pages,
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* they can't contain tuples to delete.
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*/
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npages = RelationGetNumberOfBlocks(index);
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for (blkno = BLOOM_HEAD_BLKNO; blkno < npages; blkno++)
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{
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BloomTuple *itup,
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*itupPtr,
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*itupEnd;
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buffer = ReadBufferExtended(index, MAIN_FORKNUM, blkno,
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RBM_NORMAL, info->strategy);
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LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
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gxlogState = GenericXLogStart(index);
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page = GenericXLogRegisterBuffer(gxlogState, buffer, 0);
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if (BloomPageIsDeleted(page))
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{
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UnlockReleaseBuffer(buffer);
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GenericXLogAbort(gxlogState);
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CHECK_FOR_INTERRUPTS();
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continue;
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}
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/* Iterate over the tuples */
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itup = itupPtr = BloomPageGetTuple(&state, page, FirstOffsetNumber);
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itupEnd = BloomPageGetTuple(&state, page,
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OffsetNumberNext(BloomPageGetMaxOffset(page)));
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while (itup < itupEnd)
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{
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/* Do we have to delete this tuple? */
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if (callback(&itup->heapPtr, callback_state))
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{
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stats->tuples_removed += 1;
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BloomPageGetOpaque(page)->maxoff--;
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}
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else
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{
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if (itupPtr != itup)
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{
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/*
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* If we already delete something before, we have to move
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* this tuple backward.
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*/
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memmove((Pointer) itupPtr, (Pointer) itup,
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state.sizeOfBloomTuple);
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}
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stats->num_index_tuples++;
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itupPtr = BloomPageGetNextTuple(&state, itupPtr);
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}
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itup = BloomPageGetNextTuple(&state, itup);
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}
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Assert(itupPtr == BloomPageGetTuple(&state, page,
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OffsetNumberNext(BloomPageGetMaxOffset(page))));
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/*
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* Add page to notFullPage list if we will not mark page as deleted and
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* there is a free space on it
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*/
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if (BloomPageGetMaxOffset(page) != 0 &&
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BloomPageGetFreeSpace(&state, page) > state.sizeOfBloomTuple &&
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countPage < BloomMetaBlockN)
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notFullPage[countPage++] = blkno;
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/* Did we delete something? */
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if (itupPtr != itup)
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{
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/* Is it empty page now? */
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if (BloomPageGetMaxOffset(page) == 0)
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BloomPageSetDeleted(page);
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/* Adjust pg_lower */
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((PageHeader) page)->pd_lower = (Pointer) itupPtr - page;
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/* Finish WAL-logging */
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GenericXLogFinish(gxlogState);
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}
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else
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{
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/* Didn't change anything: abort WAL-logging */
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GenericXLogAbort(gxlogState);
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}
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UnlockReleaseBuffer(buffer);
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CHECK_FOR_INTERRUPTS();
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}
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if (countPage > 0)
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{
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BloomMetaPageData *metaData;
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buffer = ReadBuffer(index, BLOOM_METAPAGE_BLKNO);
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LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
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gxlogState = GenericXLogStart(index);
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page = GenericXLogRegisterBuffer(gxlogState, buffer, 0);
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metaData = BloomPageGetMeta(page);
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memcpy(metaData->notFullPage, notFullPage, sizeof(BlockNumber) * countPage);
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metaData->nStart = 0;
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metaData->nEnd = countPage;
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GenericXLogFinish(gxlogState);
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UnlockReleaseBuffer(buffer);
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}
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return stats;
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}
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/*
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* Post-VACUUM cleanup.
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*
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* Result: a palloc'd struct containing statistical info for VACUUM displays.
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*/
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IndexBulkDeleteResult *
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blvacuumcleanup(IndexVacuumInfo *info, IndexBulkDeleteResult *stats)
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{
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Relation index = info->index;
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BlockNumber npages,
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blkno;
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BlockNumber totFreePages;
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if (info->analyze_only)
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return stats;
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if (stats == NULL)
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stats = (IndexBulkDeleteResult *) palloc0(sizeof(IndexBulkDeleteResult));
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/*
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* Iterate over the pages: insert deleted pages into FSM and collect
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* statistics.
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*/
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npages = RelationGetNumberOfBlocks(index);
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totFreePages = 0;
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for (blkno = BLOOM_HEAD_BLKNO; blkno < npages; blkno++)
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{
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Buffer buffer;
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Page page;
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vacuum_delay_point();
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buffer = ReadBufferExtended(index, MAIN_FORKNUM, blkno,
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RBM_NORMAL, info->strategy);
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LockBuffer(buffer, BUFFER_LOCK_SHARE);
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page = (Page) BufferGetPage(buffer);
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if (BloomPageIsDeleted(page))
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{
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RecordFreeIndexPage(index, blkno);
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totFreePages++;
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}
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else
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{
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stats->num_index_tuples += BloomPageGetMaxOffset(page);
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stats->estimated_count += BloomPageGetMaxOffset(page);
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}
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UnlockReleaseBuffer(buffer);
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}
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IndexFreeSpaceMapVacuum(info->index);
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stats->pages_free = totFreePages;
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stats->num_pages = RelationGetNumberOfBlocks(index);
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return stats;
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}
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