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Mark index entries "killed" when they are no longer visible to any

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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.
This commit is contained in:
Tom Lane
2002-05-24 18:57:57 +00:00
parent 2f2d05763d
commit 3f4d488022
30 changed files with 498 additions and 273 deletions
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80
src/backend/access/hash/hashscan.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/hash/hashscan.c,v 1.26 2002/05/20 23:51:41 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/access/hash/hashscan.c,v 1.27 2002/05/24 18:57:55 tgl Exp $
*
* NOTES
* Because we can be doing an index scan on a relation while we
@@ -32,8 +32,6 @@
#include "access/hash.h"
static void _hash_scandel(IndexScanDesc scan, BlockNumber blkno, OffsetNumber offno);
static bool _hash_scantouched(IndexScanDesc scan, BlockNumber blkno, OffsetNumber offno);
typedef struct HashScanListData
{
@@ -46,6 +44,10 @@ typedef HashScanListData *HashScanList;
static HashScanList HashScans = (HashScanList) NULL;
static void _hash_scandel(IndexScanDesc scan,
BlockNumber blkno, OffsetNumber offno);
/*
* AtEOXact_hash() --- clean up hash subsystem at xact abort or commit.
*
@@ -129,63 +131,51 @@ static void
_hash_scandel(IndexScanDesc scan, BlockNumber blkno, OffsetNumber offno)
{
ItemPointer current;
ItemPointer mark;
Buffer buf;
Buffer metabuf;
HashScanOpaque so;
if (!_hash_scantouched(scan, blkno, offno))
return;
metabuf = _hash_getbuf(scan->indexRelation, HASH_METAPAGE, HASH_READ);
so = (HashScanOpaque) scan->opaque;
buf = so->hashso_curbuf;
current = &(scan->currentItemData);
mark = &(scan->currentMarkData);
if (ItemPointerIsValid(current)
&& ItemPointerGetBlockNumber(current) == blkno
&& ItemPointerGetOffsetNumber(current) >= offno)
{
metabuf = _hash_getbuf(scan->indexRelation, HASH_METAPAGE, HASH_READ);
buf = so->hashso_curbuf;
_hash_step(scan, &buf, BackwardScanDirection, metabuf);
so->hashso_curbuf = buf;
}
current = &(scan->currentMarkData);
if (ItemPointerIsValid(current)
&& ItemPointerGetBlockNumber(current) == blkno
&& ItemPointerGetOffsetNumber(current) >= offno)
if (ItemPointerIsValid(mark)
&& ItemPointerGetBlockNumber(mark) == blkno
&& ItemPointerGetOffsetNumber(mark) >= offno)
{
ItemPointerData tmp;
/*
* The idea here is to exchange the current and mark positions,
* then step backwards (affecting current), then exchange again.
*/
ItemPointerData tmpitem;
Buffer tmpbuf;
tmp = *current;
*current = scan->currentItemData;
scan->currentItemData = tmp;
tmpitem = *mark;
*mark = *current;
*current = tmpitem;
tmpbuf = so->hashso_mrkbuf;
so->hashso_mrkbuf = so->hashso_curbuf;
so->hashso_curbuf = tmpbuf;
metabuf = _hash_getbuf(scan->indexRelation, HASH_METAPAGE, HASH_READ);
buf = so->hashso_curbuf;
_hash_step(scan, &buf, BackwardScanDirection, metabuf);
so->hashso_mrkbuf = buf;
tmp = *current;
*current = scan->currentItemData;
scan->currentItemData = tmp;
tmpitem = *mark;
*mark = *current;
*current = tmpitem;
tmpbuf = so->hashso_mrkbuf;
so->hashso_mrkbuf = so->hashso_curbuf;
so->hashso_curbuf = tmpbuf;
}
}
static bool
_hash_scantouched(IndexScanDesc scan,
BlockNumber blkno,
OffsetNumber offno)
{
ItemPointer current;
current = &(scan->currentItemData);
if (ItemPointerIsValid(current)
&& ItemPointerGetBlockNumber(current) == blkno
&& ItemPointerGetOffsetNumber(current) >= offno)
return true;
current = &(scan->currentMarkData);
if (ItemPointerIsValid(current)
&& ItemPointerGetBlockNumber(current) == blkno
&& ItemPointerGetOffsetNumber(current) >= offno)
return true;
return false;
}