On Mon, 2009-03-16 at 16:26 +0000, Matthew Wakeling wrote: > One possibility would be for the locks to alternate between exclusive > and > shared - that is: > > 1. Take a snapshot of all shared waits, and grant them all - > thundering > herd style. > 2. Wait until ALL of them have finished, granting no more. > 3. Take a snapshot of all exclusive waits, and grant them all, one by > one. > 4. Wait until all of them have been finished, granting no more. > 5. Back to (1) I agree with that, apart from the "granting no more" bit. Currently we queue up exclusive locks, but there is no need to since for ProcArrayLock commits are all changing different data. The most useful behaviour is just to have two modes: * exclusive-lock held - all other x locks welcome, s locks queue * shared-lock held - all other s locks welcome, x locks queue This *only* works for ProcArrayLock. -- Simon Riggs www.2ndQuadrant.com PostgreSQL Training, Services and Support - Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
