Simon Riggs wrote:
Patch works, but there's a bit I haven't finished yet - checking unique indexes.
Did plan invalidation make it safe to rely on the presence of a unique index for planning decisions?
Couldn't we also do join removal for inner joins, when there's a foreign key reference that enforces that there's one and only one matching tuple in the removed table:
SELECT child.data FROM child, parent WHERE child.fkey = parent.pkey ?
+ /* + * We can now remove join by pulling up child plan from the keeprel. + * This needs to be done considering costs, since its possible for + * a nested inner indexscan plan to be cheaper. So it isn't + * always desirable to remove the join.
Can you elaborate that a bit? I can't imagine a case where we wouldn't want to remove a join, when we know we can.
-- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-patches mailing list (pgsql-patches@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-patches
