Interesting catch, I will try to test the behavior of 'DELETE vs multiple TRUNCATE'. I'll post it here, If I discover any amazing results. On Fri, Jul 6, 2012 at 2:38 PM, Daniel Farina <daniel@xxxxxxxxxx> wrote: > 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
