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(-)
