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transaction, so as to avoid returning them out of the index AM. Saves repeated heap_fetch operations on frequently-updated rows. Also detect queries on unique keys (equality to all columns of a unique index), and don't bother continuing scan once we have found first match. Killing is implemented in the btree and hash AMs, but not yet in rtree or gist, because there isn't an equally convenient place to do it in those AMs (the outer amgetnext routine can't do it without re-pinning the index page). Did some small cleanup on APIs of HeapTupleSatisfies, heap_fetch, and index_insert to make this a little easier.
99 lines
3.1 KiB
C
99 lines
3.1 KiB
C
/*-------------------------------------------------------------------------
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*
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* relscan.h
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* POSTGRES relation scan descriptor definitions.
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*
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*
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* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $Id: relscan.h,v 1.27 2002/05/24 18:57:56 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef RELSCAN_H
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#define RELSCAN_H
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#include "utils/tqual.h"
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typedef struct HeapScanDescData
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{
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/* scan parameters */
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Relation rs_rd; /* heap relation descriptor */
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Snapshot rs_snapshot; /* snapshot to see */
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int rs_nkeys; /* number of scan keys */
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ScanKey rs_key; /* array of scan key descriptors */
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/* scan current state */
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HeapTupleData rs_ctup; /* current tuple in scan, if any */
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Buffer rs_cbuf; /* current buffer in scan, if any */
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/* NB: if rs_cbuf is not InvalidBuffer, we hold a pin on that buffer */
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ItemPointerData rs_mctid; /* marked scan position, if any */
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PgStat_Info rs_pgstat_info; /* statistics collector hook */
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} HeapScanDescData;
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typedef HeapScanDescData *HeapScanDesc;
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typedef struct IndexScanDescData
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{
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/* scan parameters */
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Relation heapRelation; /* heap relation descriptor, or NULL */
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Relation indexRelation; /* index relation descriptor */
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Snapshot xs_snapshot; /* snapshot to see */
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int numberOfKeys; /* number of scan keys */
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ScanKey keyData; /* array of scan key descriptors */
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/* signaling to index AM about killing index tuples */
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bool kill_prior_tuple; /* last-returned tuple is dead */
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bool ignore_killed_tuples; /* do not return killed entries */
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/* set by index AM if scan keys satisfy index's uniqueness constraint */
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bool keys_are_unique;
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/* scan current state */
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bool got_tuple; /* true after successful index_getnext */
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void *opaque; /* access-method-specific info */
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ItemPointerData currentItemData; /* current index pointer */
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ItemPointerData currentMarkData; /* marked position, if any */
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/*
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* xs_ctup/xs_cbuf are valid after a successful index_getnext.
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* After index_getnext_indexitem, xs_ctup.t_self contains the
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* heap tuple TID from the index entry, but its other fields are
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* not valid.
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*/
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HeapTupleData xs_ctup; /* current heap tuple, if any */
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Buffer xs_cbuf; /* current heap buffer in scan, if any */
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/* NB: if xs_cbuf is not InvalidBuffer, we hold a pin on that buffer */
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FmgrInfo fn_getnext; /* cached lookup info for AM's getnext fn */
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PgStat_Info xs_pgstat_info; /* statistics collector hook */
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} IndexScanDescData;
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typedef IndexScanDescData *IndexScanDesc;
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/* ----------------
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* IndexScanDescPtr is used in the executor where we have to
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* keep track of several index scans when using several indices
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* - cim 9/10/89
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* ----------------
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*/
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typedef IndexScanDesc *IndexScanDescPtr;
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/*
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* HeapScanIsValid
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* True iff the heap scan is valid.
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*/
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#define HeapScanIsValid(scan) PointerIsValid(scan)
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/*
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* IndexScanIsValid
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* True iff the index scan is valid.
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*/
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#define IndexScanIsValid(scan) PointerIsValid(scan)
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#endif /* RELSCAN_H */
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