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* best index for ~ ordering?
@ 2007-03-06 21:34 Gerardo Herzig <gherzig@fmed.uba.ar>
0 siblings, 1 reply; 4+ messages in thread
From: Gerardo Herzig @ 2007-03-06 21:34 UTC (permalink / raw)
To: pgsql-sql
Hi all, i have a large table with one varchar field, and im triyng to
get information about what index should i use in order to using that
index (if this is possible) for ~ searching, and/or using LIKE searching.
Thanks!
Gerardo
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: best index for ~ ordering?
@ 2007-03-06 22:28 Andrew Sullivan <ajs@crankycanuck.ca>
parent: Gerardo Herzig <gherzig@fmed.uba.ar>
0 siblings, 1 reply; 4+ messages in thread
From: Andrew Sullivan @ 2007-03-06 22:28 UTC (permalink / raw)
To: pgsql-sql
On Tue, Mar 06, 2007 at 06:34:23PM -0300, Gerardo Herzig wrote:
> Hi all, i have a large table with one varchar field, and im triyng to
> get information about what index should i use in order to using that
> index (if this is possible) for ~ searching, and/or using LIKE searching.
What sort of match are you doing? If you're doing left-anchored
searches (LIKE 'blah%') then your standard btree is good. If you're
doing unanchored searches (LIKE '%blah%' or similar) you're best doing
tsearch. If it's right-anchored, you can do an index on the reverse
of the string.
A
--
Andrew Sullivan | ajs@crankycanuck.ca
Unfortunately reformatting the Internet is a little more painful
than reformatting your hard drive when it gets out of whack.
--Scott Morris
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: best index for ~ ordering?
@ 2007-03-07 03:28 gherzig@fmed.uba.ar
parent: Andrew Sullivan <ajs@crankycanuck.ca>
0 siblings, 1 reply; 4+ messages in thread
From: gherzig@fmed.uba.ar @ 2007-03-07 03:28 UTC (permalink / raw)
To: pgsql-sql
Well, im wondering if is possible using LIKE '%blah%', even better would be
upper/lower(string) like '%blah%',
Im not at work right now, i will try it latter and makes you know about
the results of using tsearch indexing.
Thanks a lot, man!
Gerardo
> On Tue, Mar 06, 2007 at 06:34:23PM -0300, Gerardo Herzig wrote:
>> Hi all, i have a large table with one varchar field, and im triyng to
>> get information about what index should i use in order to using that
>> index (if this is possible) for ~ searching, and/or using LIKE
>> searching.
>
> What sort of match are you doing? If you're doing left-anchored
> searches (LIKE 'blah%') then your standard btree is good. If you're
> doing unanchored searches (LIKE '%blah%' or similar) you're best doing
> tsearch. If it's right-anchored, you can do an index on the reverse
> of the string.
>
> A
>
> --
> Andrew Sullivan | ajs@crankycanuck.ca
> Unfortunately reformatting the Internet is a little more painful
> than reformatting your hard drive when it gets out of whack.
> --Scott Morris
>
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>
--
Gerardo Herzig
Direccion General de Organizacion y Sistemas
Facultad de Medicina
U.B.A.
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: best index for ~ ordering?
@ 2007-03-07 18:32 Andrew Sullivan <ajs@crankycanuck.ca>
parent: gherzig@fmed.uba.ar
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Sullivan @ 2007-03-07 18:32 UTC (permalink / raw)
To: pgsql-sql
On Wed, Mar 07, 2007 at 12:28:57AM -0300, gherzig@fmed.uba.ar wrote:
> Well, im wondering if is possible using LIKE '%blah%', even better would be
> upper/lower(string) like '%blah%',
Your better bet then is either to index lower(string) or better, on
insert convert everything to lower().
A
--
Andrew Sullivan | ajs@crankycanuck.ca
The plural of anecdote is not data.
--Roger Brinner
^ permalink raw reply [nested|flat] 4+ messages in thread
end of thread, other threads:[~2007-03-07 18:32 UTC | newest]
Thread overview: 4+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2007-03-06 21:34 best index for ~ ordering? Gerardo Herzig <gherzig@fmed.uba.ar>
2007-03-06 22:28 ` Andrew Sullivan <ajs@crankycanuck.ca>
2007-03-07 03:28 ` gherzig@fmed.uba.ar
2007-03-07 18:32 ` Andrew Sullivan <ajs@crankycanuck.ca>
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