Re: Huge table searching optimization - Mailing list pgsql-performance

From Tom Lane
Subject Re: Huge table searching optimization
Date
Msg-id 23156.1270484578@sss.pgh.pa.us
Whole thread Raw
In response to Re: Huge table searching optimization  (Andres Freund)
Responses Re: Huge table searching optimization  (Oliver Kindernay)
List pgsql-performance
Andres Freund <> writes:
> On Monday 05 April 2010 16:28:35 Oliver Kindernay wrote:
>> i am using this request:
>> select url from test2 where url ~* '^URLVALUE\\s*$';

> Depending on your locale it might be sensible to create a text_pattern_ops
> index - see the following link:
> http://www.postgresql.org/docs/current/static/indexes-opclass.html

text_pattern_ops won't help for a case-insensitive search.  The best bet
here would be to index on a case-folded, blank-removed version of the
url, viz

    create index ... on (normalize(url))

    select ... where normalize(url) = normalize('URLVALUE')

where normalize() is a suitably defined function.

Or if it's okay to only store the normalized form of the string,
you could simplify that a bit.

            regards, tom lane

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