On 2015-08-10 16:58, Alexander Korotkov wrote:
On Mon, Aug 10, 2015 at 5:48 PM, Tom Lane <t...@sss.pgh.pa.us <mailto:t...@sss.pgh.pa.us>> wrote:Alexander Korotkov <a.korot...@postgrespro.ru <mailto:a.korot...@postgrespro.ru>> writes: > On Mon, Aug 10, 2015 at 1:12 PM, Petr Jelinek <p...@2ndquadrant.com <mailto:p...@2ndquadrant.com>> wrote: >> I don't understand this, there is already AmRoutine in RelationData, why >> the need for additional field for just amsupport? > We need amsupport in load_relcache_init_file() which reads > "pg_internal.init". I'm not sure this is correct place to call am_handler. > It should work in the case of built-in AM. But if AM is defined in the > extension then we wouldn't be able to do catalog lookup for am_handler on > this stage of initialization. This is an issue we'll have to face before there's much hope of having index AMs as extensions: how would you locate any extension function without catalog access? Storing raw function pointers in pg_internal.init is not an answer in an ASLR world. I think we can dodge the issue so far as pg_internal.init is concerned by decreeing that system catalogs can only have indexes with built-in AMs. Calling a built-in function doesn't require catalog access, so there should be no problem with re-calling the handler function by OID during load_relcache_init_file(). That should work, thanks! Also we can have SQL-visible functions to get amsupport and amstrategies and use them in the regression tests.
SQL-visible functions would be preferable to storing it in pg_am as keeping the params in pg_am would limit the extensibility of pg_am itself.
-- Petr Jelinek http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
