On 2017-05-02 07:12:41 +0200, Simon Riggs wrote: > /* > * The running-xacts snapshot can contain xids that were still visible > * in the procarray when the snapshot was taken, but were already > * WAL-logged as completed. They're not running anymore, so ignore > * them. > */ > if (TransactionIdDidCommit(xid) || TransactionIdDidAbort(xid)) > continue;
Ah, right. Phew ;) > What I suggest is that with logical decoding in mind we do this > 1. Inject a new record XLOG_SNAPSHOT_START at the start of > LogStandbySnapshot(). We start logical decoding from there. > 2. Record any transactions that end > 3. Now the full XLOG_RUNNING_XACTS record arrives. We apply all xacts > that are seen as running, minus any ended between 1 and 3 > This avoids the problems for the race but without holding locks while > we log XLOG_RUNNING_XACTS, something that was considered painful for > Hot Standby. I don't think that really solves it, because other transactions could just be stuck just after the XLogInsert() forever. And it'd have the issue of having to backpatch a new record. I'm working on an alternative approach, let's hope that that works out. - Andres -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
