On Fri, 2008-09-26 at 12:38 -0400, Tom Lane wrote: > Stefan Kaltenbrunner <[EMAIL PROTECTED]> writes: > > heh no log archiving - I actually said that I'm now playing with > > --truncate-before-load which seems to cause a noticeable performance (as > > in IO generated) increase but I still see >130000 context switches/s and > > a profile that looks like: > > > samples % symbol name > > 55526 16.5614 LWLockAcquire > > 29721 8.8647 DoCopy > > 26581 7.9281 CopyReadLine > > 25105 7.4879 LWLockRelease > > 15743 4.6956 PinBuffer > > 14725 4.3919 heap_formtuple > > Still a lot of contention for something, then. You might try turning on > LWLOCK_STATS (this only requires recompiling storage/lmgr/lwlock.c) to > get some evidence about what.
Probably loading a table with a generated PK or loading data in ascending sequence, so its contending heavily for the rightmost edge of the index. We need to load data a block at a time and buffer the inserts into the index also, so we don't need to lock/unlock per row. -- Simon Riggs www.2ndQuadrant.com PostgreSQL Training, Services and Support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
