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