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173 lines
3.5 KiB
C
173 lines
3.5 KiB
C
/*-------------------------------------------------------------------------
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*
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* blscan.c
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* Bloom index scan functions.
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*
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* Copyright (c) 2016-2022, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* contrib/bloom/blscan.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/relscan.h"
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#include "bloom.h"
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#include "miscadmin.h"
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#include "pgstat.h"
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#include "storage/bufmgr.h"
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#include "storage/lmgr.h"
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#include "utils/memutils.h"
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#include "utils/rel.h"
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/*
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* Begin scan of bloom index.
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*/
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IndexScanDesc
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blbeginscan(Relation r, int nkeys, int norderbys)
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{
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IndexScanDesc scan;
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BloomScanOpaque so;
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scan = RelationGetIndexScan(r, nkeys, norderbys);
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so = (BloomScanOpaque) palloc(sizeof(BloomScanOpaqueData));
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initBloomState(&so->state, scan->indexRelation);
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so->sign = NULL;
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scan->opaque = so;
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return scan;
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}
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/*
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* Rescan a bloom index.
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*/
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void
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blrescan(IndexScanDesc scan, ScanKey scankey, int nscankeys,
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ScanKey orderbys, int norderbys)
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{
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BloomScanOpaque so = (BloomScanOpaque) scan->opaque;
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if (so->sign)
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pfree(so->sign);
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so->sign = NULL;
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if (scankey && scan->numberOfKeys > 0)
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{
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memmove(scan->keyData, scankey,
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scan->numberOfKeys * sizeof(ScanKeyData));
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}
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}
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/*
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* End scan of bloom index.
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*/
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void
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blendscan(IndexScanDesc scan)
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{
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BloomScanOpaque so = (BloomScanOpaque) scan->opaque;
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if (so->sign)
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pfree(so->sign);
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so->sign = NULL;
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}
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/*
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* Insert all matching tuples into a bitmap.
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*/
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int64
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blgetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
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{
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int64 ntids = 0;
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BlockNumber blkno = BLOOM_HEAD_BLKNO,
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npages;
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int i;
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BufferAccessStrategy bas;
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BloomScanOpaque so = (BloomScanOpaque) scan->opaque;
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if (so->sign == NULL)
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{
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/* New search: have to calculate search signature */
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ScanKey skey = scan->keyData;
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so->sign = palloc0(sizeof(BloomSignatureWord) * so->state.opts.bloomLength);
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for (i = 0; i < scan->numberOfKeys; i++)
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{
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/*
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* Assume bloom-indexable operators to be strict, so nothing could
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* be found for NULL key.
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*/
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if (skey->sk_flags & SK_ISNULL)
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{
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pfree(so->sign);
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so->sign = NULL;
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return 0;
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}
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/* Add next value to the signature */
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signValue(&so->state, so->sign, skey->sk_argument,
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skey->sk_attno - 1);
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skey++;
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}
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}
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/*
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* We're going to read the whole index. This is why we use appropriate
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* buffer access strategy.
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*/
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bas = GetAccessStrategy(BAS_BULKREAD);
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npages = RelationGetNumberOfBlocks(scan->indexRelation);
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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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buffer = ReadBufferExtended(scan->indexRelation, MAIN_FORKNUM,
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blkno, RBM_NORMAL, bas);
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LockBuffer(buffer, BUFFER_LOCK_SHARE);
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page = BufferGetPage(buffer);
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TestForOldSnapshot(scan->xs_snapshot, scan->indexRelation, page);
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if (!PageIsNew(page) && !BloomPageIsDeleted(page))
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{
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OffsetNumber offset,
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maxOffset = BloomPageGetMaxOffset(page);
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for (offset = 1; offset <= maxOffset; offset++)
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{
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BloomTuple *itup = BloomPageGetTuple(&so->state, page, offset);
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bool res = true;
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/* Check index signature with scan signature */
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for (i = 0; i < so->state.opts.bloomLength; i++)
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{
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if ((itup->sign[i] & so->sign[i]) != so->sign[i])
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{
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res = false;
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break;
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}
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}
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/* Add matching tuples to bitmap */
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if (res)
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{
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tbm_add_tuples(tbm, &itup->heapPtr, 1, true);
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ntids++;
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}
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}
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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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FreeAccessStrategy(bas);
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return ntids;
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}
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