jungmin shin escribió: > I have a question about the query optimizer of a postgres. > As long as I understood through a postgres manual, the postgres query > optimizer is implemented using a *genetic algorithm.*
There is an algorithm said to be "genetic", but it only kicks in with big joins; 12 tables on the default configuration. On queries with less tables, the optimizer uses exhaustive search and lots of smarts. See http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/README?rev=1.39;content-type=text%2Fplain > I'm thinking to modify the query optimizer. > Are there any postgres version which uses typical dynamic programming > approach for query optimization? > Also, are there any body who have tried to modify the optimizer? Sure, we have a very active optimizer hacker. He is too clever for the rest of us to follow though :-( (I should speak only for myself here of course). He goes by the name of Tom Lane. -- Alvaro Herrera http://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
