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a98871b7ac
if we already have a stronger lock due to the index's table being the update target table of the query. Same optimization I applied earlier at the table level. There doesn't seem to be much interest in the more radical idea of not locking indexes at all, so do what we can ...
116 lines
4.0 KiB
C
116 lines
4.0 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) 1996-2005, 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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* $PostgreSQL: pgsql/src/include/access/relscan.h,v 1.43 2005/12/03 05:51:03 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 "access/skey.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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BlockNumber rs_nblocks; /* number of blocks to scan */
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bool rs_pageatatime; /* verify visibility page-at-a-time? */
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/* scan current state */
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bool rs_inited; /* false = scan not init'd yet */
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HeapTupleData rs_ctup; /* current tuple in scan, if any */
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BlockNumber rs_cblock; /* current block # 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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/* these fields only used in page-at-a-time mode */
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int rs_cindex; /* current tuple's index in vistuples */
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int rs_mindex; /* marked tuple's saved index */
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int rs_ntuples; /* number of visible tuples on page */
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OffsetNumber rs_vistuples[MaxHeapTuplesPerPage]; /* their offsets */
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} HeapScanDescData;
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typedef HeapScanDescData *HeapScanDesc;
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/*
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* We use the same IndexScanDescData structure for both amgettuple-based
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* and amgetmulti-based index scans. Some fields are only relevant in
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* amgettuple-based scans.
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*/
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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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bool is_multiscan; /* TRUE = using amgetmulti */
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bool have_lock; /* TRUE = holding AccessShareLock for scan */
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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. After
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* index_getnext_indexitem, xs_ctup.t_self contains the heap tuple TID
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* from the index entry, but its other fields are 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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/*
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* If keys_are_unique and got_tuple are both true, we stop calling the
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* index AM; it is then necessary for index_getnext to keep track of the
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* logical scan position for itself. It does that using unique_tuple_pos:
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* -1 = before row, 0 = on row, +1 = after row.
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*/
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int unique_tuple_pos; /* logical position */
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int unique_tuple_mark; /* logical marked position */
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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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* 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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