Re: [GENERAL] indexed regex select optimisation missing?

selkovjr@mcs.anl.gov

From: "Gene Selkov, Jr." <selkovjr@mcs.anl.gov>
To: Stuart Woolford <stuartw@newmail.net>, pgsql-general@postgreSQL.org
Date: 1999-11-04T05:23:12Z
Lists: pgsql-general
> select key from inv_word_i where word='whatever' order by count desc ;
> 
> and this is fast, however, if I use:
> 
> select key from inv_word_i where word~'^whatever.*' order by count desc ;
> 
> it is very slow.

Did you try '^whatever' instead of '^whatever.*'? Based on common
sense, the former should be much faster than the latter, which would
match any cahracter any number of times, unless the regexp is
optimized to avoid that.

--Gene