2009/4/11 Tom Lane <t...@sss.pgh.pa.us>: > Pavel Stehule <pavel.steh...@gmail.com> writes: >> 2009/4/11 Tom Lane <t...@sss.pgh.pa.us>: >>> Pavel Stehule <pavel.steh...@gmail.com> writes: >>>> I am sending small patch, that allows hooking transformation stage of >>>> parser. >>> >>> Isn't this the exact same patch we rejected several months ago? > >> What I remember, You had some objections about different behave before >> and after loading an library. > > No, I was complaining that a hook right there is useless and expensive. > transformExpr() is executed multiple times per query, potentially a very > large number of times per query; so even testing to see if a hook exists > is not a negligible cost. And I have not seen anything I regard as a > convincing demonstration of use-case that can't be handled as well or > better in some other way. >
I will do some performance testing. But effect of empty hook should be similar to testing some GUC now. But I have to do some metering. Actually transformExpr contains relative big case now, and empty hook has similar performance effect as new parser node. I sent some examples, that helps to people with database migration (some are obscure, I know - Oracle empty string support - it's +/- joke, there are more serious samples ). And I am preparing JSON support as example of some comfortable libraries. Next use case should be in enhancing of db-link functions. http://archives.postgresql.org/pgsql-hackers/2009-03/msg01239.php regards Pavel Stehule > regards, tom lane > -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
