Re: [GENERAL] indexed regex select optimisation missing?

Peter Eisentraut <e99re41@docs.uu.se>

From: Peter Eisentraut <e99re41@DoCS.UU.SE>
To: Stuart Woolford <stuartw@newmail.net>
Cc: "Gene Selkov, Jr." <selkovjr@mcs.anl.gov>, pgsql-general@postgreSQL.org
Date: 1999-11-04T09:40:21Z
Lists: pgsql-general
On Thu, 4 Nov 1999, Stuart Woolford wrote:

> unfortunately '^whatever.*' is what I'm trying to locate (ie: all words
> starting with whatever, but with nay trailing text), the problem seems to be in
> the termination of the index scan, not in the actual regex match (which actually
> seems very good, speed wise..) otherwise I could just use ='whatever', which
> runs very very fast.

Isn't "all words that start with whatever but without trailing text" the
same as = 'whatever'? From a regex point of view '^whatever' and
'^whatever.*' are exactly equivalent, but I can see where one could fail
to optimize properly. But that could even be a problem in the regex
library, which is not any of the PostgreSQL developers' domain and which
is used in other products as well.

	-Peter

-- 
Peter Eisentraut                  Sernanders vaeg 10:115
peter_e@gmx.net                   75262 Uppsala
http://yi.org/peter-e/            Sweden