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Insert CHECK_FOR_INTERRUPTS() calls into btree and hash index scans at the

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points where we step right or left to the next page.  This should ensure
reasonable response time to a query cancel request during an unsuccessful
index scan, as seen in recent gripe from Marc Cousin.  It's a bit trickier
than it might seem at first glance, because CHECK_FOR_INTERRUPTS() is a no-op
if executed while holding a buffer lock.  So we have to do it just at the
point where we've dropped one page lock and not yet acquired the next.

Remove CHECK_FOR_INTERRUPTS calls at the top level of btgetbitmap and
hashgetbitmap, since they're pointless given the added checks.

I think that GIST is okay already --- at least, there's a CHECK_FOR_INTERRUPTS
at a plausible-looking place in gistnext().  I don't claim to know GIN well
enough to try to poke it for this, if indeed it has a problem at all.

This is a pre-existing issue, but in view of the lack of prior complaints
I'm not going to risk back-patching.
This commit is contained in:
Tom Lane
2009-05-05 19:36:32 +00:00
parent 2aa5ca952f
commit 8f348112f3
4 changed files with 21 additions and 18 deletions
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5
src/backend/access/hash/hash.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/hash/hash.c,v 1.109 2009/03/24 20:17:11 tgl Exp $
* $PostgreSQL: pgsql/src/backend/access/hash/hash.c,v 1.110 2009/05/05 19:36:32 tgl Exp $
*
* NOTES
* This file contains only the public interface routines.
@@ -22,7 +22,6 @@
#include "access/relscan.h"
#include "catalog/index.h"
#include "commands/vacuum.h"
#include "miscadmin.h"
#include "optimizer/cost.h"
#include "optimizer/plancat.h"
#include "storage/bufmgr.h"
@@ -297,8 +296,6 @@ hashgetbitmap(PG_FUNCTION_ARGS)
{
bool add_tuple;
CHECK_FOR_INTERRUPTS();
/*
* Skip killed tuples if asked to.
*/

7
src/backend/access/hash/hashsearch.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/hash/hashsearch.c,v 1.55 2009/01/01 17:23:35 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/hash/hashsearch.c,v 1.56 2009/05/05 19:36:32 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -16,6 +16,7 @@
#include "access/hash.h"
#include "access/relscan.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "storage/bufmgr.h"
#include "utils/rel.h"
@@ -74,6 +75,8 @@ _hash_readnext(Relation rel,
blkno = (*opaquep)->hasho_nextblkno;
_hash_relbuf(rel, *bufp);
*bufp = InvalidBuffer;
/* check for interrupts while we're not holding any buffer lock */
CHECK_FOR_INTERRUPTS();
if (BlockNumberIsValid(blkno))
{
*bufp = _hash_getbuf(rel, blkno, HASH_READ, LH_OVERFLOW_PAGE);
@@ -94,6 +97,8 @@ _hash_readprev(Relation rel,
blkno = (*opaquep)->hasho_prevblkno;
_hash_relbuf(rel, *bufp);
*bufp = InvalidBuffer;
/* check for interrupts while we're not holding any buffer lock */
CHECK_FOR_INTERRUPTS();
if (BlockNumberIsValid(blkno))
{
*bufp = _hash_getbuf(rel, blkno, HASH_READ,