On 2015-03-11 12:07:20 -0400, Tom Lane wrote: > Andres Freund <and...@2ndquadrant.com> writes: > > On 2015-03-11 14:40:16 +0000, Andrew Gierth wrote: > >> ,but even without doing that, there's a strong > >> argument that it should be increased to at least the order of 100. > > Nyet ... at least not without you actually making that argument, with > numbers, rather than just handwaving. We use 100 for plpgsql and suchlike > functions. I'd be OK with making it 10 just on general principles, but > claiming that it's as expensive as a plpgsql function requires > evidence.
I'll note that you proposed a higher cost than 10 years back ;): http://www.postgresql.org/message-id/8971.1255891...@sss.pgh.pa.us What you said back then makes sense to me: On 2009-10-18 14:50:43 -0400, Tom Lane wrote: > In another case I was looking at just now, it seems that to_tsquery() > and to_tsvector() are noticeably slower than most other built-in > functions, which is not surprising given the amount of mechanism that > gets invoked inside them. It would be useful to tell the planner > about that to discourage it from picking seqscan plans that involve > repeated execution of these functions. A trivial comparison shows with a simple plpgsql function: CREATE FUNCTION a_simple_plpgsql_function(a text) RETURNS text LANGUAGE plpgsql AS $$BEGIN RETURN repeat(a, 3);END;$$; SELECT a_simple_plpgsql_function('This is a long sentence in english. Or maybe not so long after all. But it includes a Metal Ümlaut. And parens: ()! Also a number: ' ||g.i) FROM generate_series(1, 10000) g(i) Time: 32.898 ms and SELECT to_tsvector('english', 'This is a long sentence in english. Or maybe not so long after all. But it includes a Metal Ümlaut. And parens: ()! Also a number: ' ||g.i) FROM generate_series(1, 10000) g(i); Time: 450.996 ms Given that this is a short sentence and a simple text search configuration a factor of 10 between them doesn't sound wrong. This is obviously completely unscientific, but ... Greetings, Andres Freund -- Andres Freund 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
