Tom Lane kirjutas R, 20.09.2002 kell 04:49: > Bruce Momjian <[EMAIL PROTECTED]> writes: > > Christopher Kings-Lynne wrote: > >> Has anyone given much thought as to perhaps we could just drop multiple > >> inheritance from Postgres? > > > I am for it. Multiple inheritance is more of a mess than a help. > > I'm not agin it ... but if that's the lay of the land then we have > no need to apply a last-minute catalog reformatting to fix a > multiple-inheritance bug.
What I'm actually envisioning for PostgreSQL inheritance is model similar to (my understanding of) SQL99 : 1. Single "data" inheritance for SELECT/INSERT/UPDATE/DELETE , meaning that the set of inherited tables any such command operates on comes from a single-inheritance hierarchy the SQL99 syntax for defining tables is CREATE TABLE child ( ... ) UNDER parent; 2. This single inheritance also applies both to "tuple-level" constraints (not null, check) and to "relation-level" constraints - unique, primary and foreign keys. 3. Multiple "interface-only" inheritance the SQL99 syntax for defining tables is CREATE TABLE child ( ..., LIKE othertable, LIKE yetanothertable, ); which would behave like our current multiple inheritance, only without affecting SELECT/INSERT/UPDATE/DELETE and "relation-level" constraints. 4. "tuple-level" constraints should still be inherited 5. function selection for functions defined on row typoes should be able to select both from among functions defined over "data" inheritance parents and "interface-only" inheritance parents. 5 such selection should be dynamic (scan-time) for queries running over inheritance trees. (SELECT without ONLY , formely SELECT*) > This patch is off the "must fix for 7.3" list, no? I still think that this should be fixed in 7.3, but the inhcount attribute should show all tables where the column is defined, not just inherited. The default, no-inheritance case should set the column to 1. ------------- Hannu ---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://archives.postgresql.org
