Michael Paquier <michael.paqu...@gmail.com> writes: > To put it short, it should not be possible to drop a NOT NULL > constraint on a child relation when its parent table is using it, this > should only be possible from the parent. Attached is a patch handling > this problem by adding a new function in pg_inherits.c to fetch the > list of parent relations for a given relation OID, and did some > refactoring to stick with what is done when scanning child relations.
This doesn't sound like the right approach; in particular, it won't really help for deciding whether to propagate a DROP NOT NULL on a parent rel to its children. What we've discussed in the past is to store NOT NULL constraints in pg_constraint, much like CHECK constraints are already, and use use-count logic identical to the CHECK case to keep track of whether NOT NULL constraints are inherited or not. My feeling is that we'd keep the pg_attribute.attnotnull field and continue to drive actual enforcement off that, but it would just reflect a summary of the pg_constraint state. IIRC, Alvaro posted a WIP patch for that awhile back. Not sure what the current state is. regards, tom lane -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers