On May 29, 2017 11:58:05 AM PDT, Petr Jelinek <petr.jeli...@2ndquadrant.com> wrote: >On 27/05/17 17:17, Andres Freund wrote: >> >> >> On May 27, 2017 9:48:22 AM EDT, Petr Jelinek ><petr.jeli...@2ndquadrant.com> wrote: >>> Actually, I guess it's the pid 47457 (COPY process) who is actually >>> running the xid 73322726. In that case that's the same thing >Masahiko >>> Sawada reported [1]. Which basically is result of snapshot builder >>> waiting for transaction to finish, that's normal if there is a long >>> transaction running when the snapshot is being created (and the COPY >is >>> a long transaction). >> >> Hm. I suspect the issue is that the exported snapshot needs an xid >for some crosscheck, and that's what we're waiting for. Could you >check what happens if you don't assign one and just content the error >checks out? Not at my computer, just theorizing. >> > >I don't think that's it, in my opinion it's the parallelization of >table >data copy where we create snapshot for one process but then the next >one >has to wait for the first one to finish. Before we fixed the >snapshotting, the second one would just use the ondisk snapshot so it >would work fine (except the snapshot was corrupted of course). I wonder >if we could somehow give it a hint to ignore the read-only txes, but >then we have no way to enforce the txes to stay read-only so it does >not >seem safe.
Read-only txs have no xid ... -- Sent from my Android device with K-9 Mail. Please excuse my brevity. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
