Re: Regex Query Index question - Mailing list pgsql-general

From Naoko Reeves
Subject Re: Regex Query Index question
Date
Msg-id CAGoos14s12ru1jEzkvoJuEp0gA7oaWeeFn6DJcyVBZXP+ZzTGQ@mail.gmail.com
Whole thread Raw
In response to Re: Regex Query Index question  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Regex Query Index question
List pgsql-general
Tom,
Thank you for your quick reply. Data start with "(123" only returns 28 records where as phone number start with"[123" returns 1.
Changed the data so that both will return 1 row. 

One with "(999" query takes about 30 seconds (30983ms) without index.
One with "[999" take about 28 ms with index.

Yes, standard_conforming_strings is ON.
Also forgot to mentioned the version:
select version() >> "PostgreSQL 8.4.6 on i386-apple-darwin, compiled by GCC i686-apple-darwin8-gcc-4.0.1 (GCC) 4.0.1 (Apple Computer, Inc. build 5370), 32-bit"

Thank you very much for your time.

Naoko Reeves

On Thu, Aug 11, 2011 at 3:49 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Naoko Reeves <naokoreeves@gmail.com> writes:
> I have query phone number in database as follows:
> [123) 456-7890
> (123) 456-7890

> When I query like this:

> SELECT * FROM phone

> WHERE phone_number ~ ('^\[123' || '[-\s\)]{0,2}' || '456' || '[-\s\)]{0,2}'
> || '7890')

> it use Index but if I query like this (notice first character is
> open parenthesis instead of open square blacket ) :

> SELECT phn_fk_key FROM phn WHERE

> phn_fk_table = 14

> AND llx_decrypt(phn_phone_enc) ~ ('^\(123' || '[-\s\)]{0,2}' || '456' ||
> '[-\s\)]{0,2}' || '7890')

> It doesn't use Index....

Probably it thinks the index isn't selective enough for that case.  How
many entries are there starting with "(123"?

(BTW, I assume you've got standard_conforming_strings turned on, else
there are some other issues with these backslashes ...)

                       regards, tom lane



--
Naoko Reeves

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