On 11 May 2012 11:16, Evan Martin <postgresql@xxxxxxxxxxxxxxxxx> wrote: > I'm running a bulk import application against PostgreSQL 9.1.3, which has > several stages and each stage follows the same general pattern: > > BEGIN TRANSACTION > DELETE (many rows) > > CREATE SAVEPOINT > INSERT > ... > RELEASE SAVEPOINT > > CREATE SAVEPOINT > INSERT > INSERT > ... half an hour of inserts later ... > RELEASE SAVEPOINT > > COMMIT TRANSACTION > > I find that for one particular stage of the import the RELEASE SAVEPOINT > command consistently takes about 6 minutes, while for the rest of them it's > very quick. COMMIT TRANSACTION is always very quick. > > At first I thought the discrepancy may be because that particular stage has > many INSERT statements inside one savepoint, while other stages create many > savepoints with a small amount of work in each. However, if I take out the > savepoints entirely then the COMMIT TRANSACTION statement for that stage > takes 6 minutes, while for the rest of them it's still very quick. > > Could anyone explain what may be happening here? What is PostgreSQL doing > when I call RELEASE SAVEPOINT that it seems to otherwise do in COMMIT > TRANSACTION? Sounds interesting. Please can you produce a test case that demonstrates this, then post the SQL file and an output of a run that shows the negative timing? Thanks -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
