On Fri, Jul 6, 2012 at 4:29 AM, Craig Ringer <ringerc@xxxxxxxxxxxxx> wrote: > 1) Truncate each table. It is too slow, I think, especially for empty > tables. > > Really?!? TRUNCATE should be extremely fast, especially on empty tables. > > You're aware that you can TRUNCATE many tables in one run, right? > > TRUNCATE TABLE a, b, c, d, e, f, g; I have seen in "trivial" cases -- in terms of data size -- where TRUNCATE is much slower than a full-table DELETE. The most common use case for that is rapid setup/teardown of tests, where it can add up quite quickly and in a very big way. This is probably an artifact the speed of one's file system to truncate and/or unlink everything. I haven't tried a multi-truncate though. Still, I don't know a mechanism besides slow file system truncation time that would explain why DELETE would be significantly faster. -- fdr -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
