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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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47
src/backend/access/nbtree/nbtree.c
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@ -12,7 +12,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtree.c,v 1.89 2002/05/20 23:51:41 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtree.c,v 1.90 2002/05/24 18:57:55 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -271,6 +271,7 @@ btinsert(PG_FUNCTION_ARGS)
char *nulls = (char *) PG_GETARG_POINTER(2);
ItemPointer ht_ctid = (ItemPointer) PG_GETARG_POINTER(3);
Relation heapRel = (Relation) PG_GETARG_POINTER(4);
bool checkUnique = PG_GETARG_BOOL(5);
InsertIndexResult res;
BTItem btitem;
IndexTuple itup;
@ -280,7 +281,7 @@ btinsert(PG_FUNCTION_ARGS)
itup->t_tid = *ht_ctid;
btitem = _bt_formitem(itup);
res = _bt_doinsert(rel, btitem, rel->rd_uniqueindex, heapRel);
res = _bt_doinsert(rel, btitem, checkUnique, heapRel);
pfree(btitem);
pfree(itup);
@ -296,14 +297,16 @@ btgettuple(PG_FUNCTION_ARGS)
{
IndexScanDesc scan = (IndexScanDesc) PG_GETARG_POINTER(0);
ScanDirection dir = (ScanDirection) PG_GETARG_INT32(1);
bool res;
BTScanOpaque so = (BTScanOpaque) scan->opaque;
Page page;
OffsetNumber offnum;
bool res;
/*
* If we've already initialized this scan, we can just advance it in
* the appropriate direction. If we haven't done so yet, we call a
* routine to get the first item in the scan.
*/
if (ItemPointerIsValid(&(scan->currentItemData)))
{
/*
@ -312,11 +315,47 @@ btgettuple(PG_FUNCTION_ARGS)
* buffer, too.
*/
_bt_restscan(scan);
/*
* Check to see if we should kill the previously-fetched tuple.
*/
if (scan->kill_prior_tuple)
{
/*
* Yes, so mark it by setting the LP_DELETE bit in the item flags.
*/
offnum = ItemPointerGetOffsetNumber(&(scan->currentItemData));
page = BufferGetPage(so->btso_curbuf);
PageGetItemId(page, offnum)->lp_flags |= LP_DELETE;
/*
* Since this can be redone later if needed, it's treated the
* same as a commit-hint-bit status update for heap tuples:
* we mark the buffer dirty but don't make a WAL log entry.
*/
SetBufferCommitInfoNeedsSave(so->btso_curbuf);
}
/*
* Now continue the scan.
*/
res = _bt_next(scan, dir);
}
else
res = _bt_first(scan, dir);
/*
* Skip killed tuples if asked to.
*/
if (scan->ignore_killed_tuples)
{
while (res)
{
offnum = ItemPointerGetOffsetNumber(&(scan->currentItemData));
page = BufferGetPage(so->btso_curbuf);
if (!ItemIdDeleted(PageGetItemId(page, offnum)))
break;
res = _bt_next(scan, dir);
}
}
/*
* Save heap TID to use it in _bt_restscan. Then release the read
* lock on the buffer so that we aren't blocking other backends.