On Thu, Sep 1, 2016 at 12:00 AM, Andres Freund <and...@anarazel.de> wrote: > On 2016-08-31 14:23:41 -0400, Tom Lane wrote: >> Andres Freund <and...@anarazel.de> writes: >> > On 2016-08-31 13:59:48 -0400, Tom Lane wrote: >> >> You are ignoring the performance costs associated with eating 100x more >> >> shared buffer space than necessary. >> >> > I doubt that's measurable in any real-world scenario. You seldomly have >> > hundreds of thousands of sequences that you all select from at a high >> > rate. >> >> If there are only a few sequences in the database, cross-sequence >> contention is not going to be a big issue anyway. > > Isn't that *precisely* when it's going to matter? If you have 5 active > tables & sequences where the latter previously used independent locks, > and they'd now be contending on a single lock. >
I may be missing something here, but why would it contend on a lock, as per locking scheme proposed by Alvaro, access to sequence object will need a share lock on buffer page. -- With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers