[HACKERS] effective SELECT from child tables

[Ilia Kantor]

Let table A be inherited by A1, A2, A3.   How to select from A records where actual relations are A1, A2 ?   I found a way somewhere, it sounds like SELECT  … WHERE tableoid IN (a1.oid, a2.oid), but tableoid checks actually do seq scan.   Like: SELECT * FROM sometable WHERE tableoid =anything will do seq. scan on sometable..   So such way seems very ineffective: it seq scans and filters records..   Maybe new constraint_exclusion staff could help to exclude non-matching tables from inheritance query ?