On Thu, May 14, 2009 at 1:28 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Simon Riggs <si...@2ndquadrant.com> writes: >> In a thread on -perform it has been observed that our Read-Only >> scalability is not as good as it could be. One problem being that we >> need to scan the whole of the ProcArray to derive a snapshot, which >> becomes the dominant task with many users. > > GetSnapshotData doesn't take an exclusive lock. Neither does start or > end of a read-only transaction. AFAIK there is no reason, and certainly > no shred of experimental evidence, to think that ProcArrayLock > contention is the bottleneck for read-only scenarios.
I think Simon's point was that it is O(n) rather than O(1), not that it took an exclusive lock. ...Robert -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
