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its second pass over the table. It has to start at block zero, else the "merge join" logic for detecting which TIDs are already in the index doesn't work. Hence, extend heapam.c's API so that callers can enable or disable syncscan. (I put in an option to disable buffer access strategy, too, just in case somebody needs it.) Per report from Hannes Dorbath.
107 lines
3.8 KiB
C
107 lines
3.8 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) 1996-2008, 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 1.60 2008/01/14 01:39:09 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 "storage/bufpage.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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bool rs_bitmapscan; /* true if this is really a bitmap scan */
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bool rs_pageatatime; /* verify visibility page-at-a-time? */
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bool rs_allow_strat; /* allow or disallow use of access strategy */
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bool rs_allow_sync; /* allow or disallow use of syncscan */
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/* state set up at initscan time */
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BlockNumber rs_nblocks; /* number of blocks to scan */
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BlockNumber rs_startblock; /* block # to start at */
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BufferAccessStrategy rs_strategy; /* access strategy for reads */
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bool rs_syncscan; /* report location to syncscan logic? */
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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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/* these fields only used in page-at-a-time mode and for bitmap scans */
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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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/* 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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/* index access method's private state */
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void *opaque; /* access-method-specific info */
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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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TransactionId xs_prev_xmax; /* previous HOT chain member's XMAX, if any */
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OffsetNumber xs_next_hot; /* next member of HOT chain, if any */
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bool xs_hot_dead; /* T if all members of HOT chain are dead */
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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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