Ben <bench@silentmedia.com> writes:
> Wouldn't it need to check the unique constraint (an index on the table)
> before the insert can succeed? It seems like it would be better to check
> the index than to do a full table scan to try to satisfy that constraint.
Postgres contains no code that would even consider doing a seqscan for a
uniqueness check; it could not work because of race-condition considerations,
never mind performance.
You have not given us any clue about where the seqscans are really
coming from ... have you got any user-defined triggers, SQL functions in
CHECK constraints, stuff like that?
regards, tom lane