On Fri, Oct 26, 2018 at 10:45:40AM -0500, Justin Pryzby wrote: > On Thu, Oct 25, 2018 at 10:43:10AM -0600, Dave E Martin wrote: > > If SELECT is confident enough to limit itself to one partition, why isn't > > DELETE (or UPDATE)? > > Because of this limitation: > > https://www.postgresql.org/docs/current/static/ddl-partitioning.html#DDL-PARTITION-PRUNING > |Currently, pruning of partitions during the planning of an UPDATE or DELETE > |command is implemented using the constraint exclusion method (however, it is > |controlled by the enable_partition_pruning rather than constraint_exclusion) — > |see the following section for details and caveats that apply. I meant to add that one can use a redundant constraints in addition to the partition bounds, both specifying the same condition. That also allows detaching and re-attaching the partition without a table scan (which is why we do it). Justin
