Re: constraint with reference to the same table
Victor Yegorov <viy@nordlb.lv>
From: Victor Yegorov <viy@nordlb.lv>
To: Stephan Szabo <sszabo@megazone23.bigpanda.com>
Cc: Rudi Starcevic <rudi@oasis.net.au>, Postgres Performance <pgsql-performance@postgresql.org>
Date: 2003-05-15T01:03:41Z
Lists: pgsql-performance
* Stephan Szabo <sszabo@megazone23.bigpanda.com> [15.05.2003 03:54]: > > That can be a win, but if you're actually dropping and adding the > constraint again it may not be on large tables since it'll still do a > whole bunch of index lookups to check the existing rows when the alter > table add constraint happens. Disabling triggers and re-enabling them is > faster but breaks the guarantee of the constraint. You're right. I thought of big tables after posting the reply. My solution is suitable for my case, i.e. not so big tables. Returning to the very first question I asked. May be it is usefull to implicitly create index on foreign key columns? Actually, untill you had pointed on seq. scans, I thought Postgres is using internal indicies - don't ask me why. -- Victor Yegorov