On Thu, Mar 5, 2015 at 4:44 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Tomas Vondra <tomas.von...@2ndquadrant.com> writes: > > On 5.3.2015 16:01, Gunnlaugur Thor Briem wrote: > >> - postgres version is 9.1.13 > > > The only thing I can think of is some sort of memory exhaustion, > > resulting in swapping out large amounts of memory. > > I'm wondering about the issue addressed by commit fccebe421 ("Use > SnapshotDirty rather than an active snapshot to probe index endpoints"). > Now, that was allegedly fixed in 9.1.13 ... but if the OP were confused > and this server were running, say, 9.1.12, that could be a viable > explanation. Another possibly viable explanation for seeing the issue > in 9.1.13 would be if I fat-fingered the back-patch somehow :-(. >
The back patch into 9.1.13 seems to have worked. psql -c 'create table foo (x integer ); create index on foo(x);insert into foo select * from generate_series(1,10000); analyze foo;' perl -le 'use DBI; my $dbh=DBI->connect("DBi:Pg:"); $dbh->begin_work(); foreach (1..1e6) {$dbh->do("insert into foo values ($_)") or die; }; $dbh->rollback()' & while (true); do pgbench -T5 -c4 -j4 -n -f <(echo "explain select count(*) from foo a join foo b using (x);"); done on 9.1.12 this slows down dramatically and on 9.1.13 it does not. Cheers, Jeff