Michael Monnerie <michael.monnerie@xxxxxxxxxxxxxxxxxxx> writes: > On Dienstag 05 Mai 2009 Tom Lane wrote: >> Apparently this is just an index, not a constraint (the difference >> being that it was made with CREATE INDEX, not ALTER TABLE ADD >> CONSTRAINT). Try > Is there a performance difference? No. A primary key or unique constraint is implemented by creating a unique index (and, for PK, also by creating NOT NULL constraints on the columns). After that, the only visible difference is that there's an entry in pg_constraint, or not. There are some minor behavioral differences --- if memory serves, you need a PK constraint entry to persuade a REFERENCES constraint that it should consider a given column as the default reference target --- but no performance difference. regards, tom lane -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
