On Thu, Apr 25, 2013 at 12:17 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > The cause is that each one will wait for all older snapshots to be > gone --- and it does that before dropping its own snapshot, so that the > other ones will see it as something to be waited out too.
This makes sense. Thank you for explaining. > Since we know that C.I.C. executes in its own transaction, and there > can't be more than one on the same table due to locking, it seems to me > that it'd be safe to drop our own snapshot before waiting for other > xacts to end. That is, we could just rearrange the last few steps in > DefineIndex(), taking care to save snapshot->xmin before we destroy the > snapshot so that we still have that value to pass to > GetCurrentVirtualXIDs(). Seems reasonable to me. Looks like a fix landed in master yesterday: http://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=c3d09b3bd23f5f65b5eb8124a3c7592dad85a50c Many thanks to Tom and all the pgsql-hackers for all the work you do! Paul -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers