You could increase statistics or try contrib/tsearch2 Oleg On Fri, 7 Oct 2005, han.holl@xxxxxxxxxxxxxxxxxxxx wrote:
Hello, We have a table of people with a date-of-birth and a surname, both indexed. We have queries like this: select report from table where dateofbirth = '1966-12-12' and surname like 'boer%' The planner estimates that in a 1.5M record table 'boer%' will have one record and 1966-12-12 about 40. Unfortunately, names are not evenly distributed, and in some combinations it will have to process many thousands of records. On some older and slower systems, this hurts. Is there a way to tell the planner to always prefer the dateofbirth index ? Alternatively, to inform it about the wildly uneven distribution of surnames (this must be even worse in China). A third possibility would be to rewrite such a query as a nested query: is there a rewrite query - hook (like apaches mod_rewrite) available ? Or is there a somewhere a proxy-server that could do this ? Cheers, Han Holl ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
Regards, Oleg _____________________________________________________________ Oleg Bartunov, sci.researcher, hostmaster of AstroNet, Sternberg Astronomical Institute, Moscow University (Russia) Internet: oleg@xxxxxxxxxx, http://www.sai.msu.su/~megera/ phone: +007(095)939-16-83, +007(095)939-23-83 ---------------------------(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
