Prev: Patch to show individual statement latencies in pgbench output
Next: Obtain a University Degree based on your professional experience for a more satisfactory life. admonishing akenes aglycone
From: Henk Enting on 29 Jul 2010 06:57 Hi, We ran into a problem on 9.0beta3 with check constraints using table inheritance in a multi-level hierarchy with multiple inheritance. A test script is provided below and a proposed patch is attached to this email. Regards, Henk Enting, Yeb Havinga MGRID B.V. http://www.mgrid.net /* First, create a local inheritance structure: level_0_parent level_0_child inherits level_0_parent This structure is the base level. The table definition and also check constraints are defined on this level. Add two levels that inherit this structure: level_1_parent inherits level_0_parent level_1_child inherits level_1_parent, level_0_child level_2_parent inherits level_1_parent level_2_child inherits level_2_parent, level_1_child BTW: there is a reason that we want e.g. level_1_child to inherit from both level_1_parent and level_0_child: we want the data of level_1_child to be visible in both level_0_child and level_1_parent */ DROP SCHEMA IF EXISTS test_inheritance CASCADE; CREATE SCHEMA test_inheritance; SET search_path TO test_inheritance; CREATE TABLE level_0_parent (i int); CREATE TABLE level_0_child (a text) INHERITS (level_0_parent); CREATE TABLE level_1_parent() INHERITS (level_0_parent); CREATE TABLE level_1_child() INHERITS (level_0_child, level_1_parent); CREATE TABLE level_2_parent() INHERITS (level_1_parent); CREATE TABLE level_2_child() INHERITS (level_1_child, level_2_parent); -- Now add a check constraint on the top level table: ALTER TABLE level_0_parent ADD CONSTRAINT a_check_constraint CHECK (i IN (0,1)); /* Check the "coninhcount" attribute of pg_constraint Doxygen says this about the parameter: coninhcount: Number of times inherited from direct parent relation(s) On our machine (running 9.0beta3) the query below returns a coninhcount of 3 for the level_2_child table. This doesn't seem correct because the table only has two direct parents. */ SELECT t.oid, t.relname, c.coninhcount FROM pg_class t JOIN pg_constraint c ON (c.conrelid = t.oid) JOIN pg_namespace n ON (t.relnamespace = n.oid) WHERE n.nspname = 'test_inheritance' ORDER BY t.oid; -- Next, drop the constraint on the top level table ALTER TABLE level_0_parent DROP CONSTRAINT a_check_constraint; /* The constraint should now be dropped from all the tables in the hierarchy, but the constraint hasn't been dropped on the level_2_child table. It is still there and has a coninhcount of 1. */ SELECT t.oid, t.relname, c.conname, c.coninhcount FROM pg_class t JOIN pg_constraint c ON (c.conrelid = t.oid) JOIN pg_namespace n ON (t.relnamespace = n.oid) WHERE n.nspname = 'test_inheritance' ORDER BY t.oid; /* Trying to drop this constraint that shouldn't be there anymore won't work. The "drop constraint" statement below returns: ERROR: cannot drop inherited constraint "a_check_constraint" of relation "level_2_child" NB after fixing this bug, the statement should return "constraint does not exist" */ ALTER TABLE level_2_child DROP CONSTRAINT a_check_constraint; |