From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | pgsql-committers(at)postgresql(dot)org |
Subject: | pgsql: Ensure that seqscans check for interrupts at least once per page |
Date: | 2012-05-22 23:43:04 |
Message-ID: | E1SWyjI-0007Pt-GK@gemulon.postgresql.org |
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Lists: | pgsql-committers |
Ensure that seqscans check for interrupts at least once per page.
If a seqscan encounters many consecutive pages containing only dead tuples,
it can remain in the loop in heapgettup for a long time, and there was no
CHECK_FOR_INTERRUPTS anywhere in that loop. This meant there were
real-world situations where a query would be effectively uncancelable for
long stretches. Add a check placed to occur once per page, which should be
enough to provide reasonable response time without adding any measurable
overhead.
Report and patch by Merlin Moncure (though I tweaked it a bit).
Back-patch to all supported branches.
Branch
------
master
Details
-------
http://git.postgresql.org/pg/commitdiff/ed962fd712bbc0836437c8f789d9152aca5711b5
Modified Files
--------------
src/backend/access/heap/heapam.c | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)
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