Postgres Pro
Downloads
Home   >   mailing lists

Thread: Select like when searching for whole word and optimizing it

Select like when searching for whole word and optimizing it

From
Michal Samek
Date:
In my e-shop I'm using the searching based on select like command;
something like
SELECT * FROM kat WHERE name LIKE '%some_text%';
and when searching for the whole word:
SELECT * FROM kat WHERE name LIKE '% some_text %';
For this is necessary to maintain the name column with one space added
before and after the name column value (to match starting and ending
words). It's working but very ugly. 

Maybe there is some better way to search for the whole word? 

And another question, is there some way to optimize the SELECT LIKE
querry? I know that when I send something like "SELECT * FROM kat WHERE
name LIKE 'blabla%';" postgresql uses the index but not when the search
string begins with '%'... My table is quickly growing and now I can feel
the speed of my web is impacted a lot. 

There is a lot of same values in the name field (for ex. 'QUEEN' about
40 times etc.) - I could make a table with unique only name values and
point to them from the main table kat. Will the searching be more
effective then? 

Thanks for any help; I hope it's interesting not only for me :) 
-- 
Michal Samek, Tony distribuce s.r.o.
webmaster@tony.cz  (++420659/321350)
ICQ: 38607210

Re: [SQL] Select like when searching for whole word and optimizing it

From
Tom Lane
Date:
Michal Samek <webmaster@tony.cz> writes:
> Maybe there is some better way to search for the whole word? 

I think you want to build a secondary table and search that.
Take a look at the stuff in contrib/fulltextindex; it may solve your
problem as-is, and if not you can probably adapt it to your needs...
        regards, tom lane

Re: [SQL] Select like when searching for whole word and optimizing it -- regexp?

From
"Emils Klotins"
Date:
[9 Jun 99,, 10:41] Michal Samek wrote:

> In my e-shop I'm using the searching based on select like command;
> something like
> SELECT * FROM kat WHERE name LIKE '%some_text%';
> and when searching for the whole word:
> SELECT * FROM kat WHERE name LIKE '% some_text %';
> For this is necessary to maintain the name column with one space added
> before and after the name column value (to match starting and ending
> words). It's working but very ugly. 
> 
> Maybe there is some better way to search for the whole word? 
Try regexp searching. Don't know if available at 6.4, but definitely is there at 6.5
SELECT * FROM kat WHERE name ~* ' your regexp ';




Emils Klotins       e-mail: emils@mail.usis.bkc.lv
Systems Manager     URL: http://www.usis.bkc.lv/
USIS Riga           7 Smilsu Str., Riga LV1050, LATVIA

Re: [SQL] Select like when searching for whole word and optimizing it

From
Oleg Bartunov
Date:
I use regex  '( |^)io([^A-z]|$)' to find word 'io'
For example
select a.msg_id,b.key_id 
from publications  a, keywords b where a.title ~* ('( |^)'||b.name||'([^A-z]|$)') 
and b.key_id in   ( select key_id from keywords);
This match word (b.name) in most cases.
Regards,    Oleg

On Wed, 9 Jun 1999, Michal Samek wrote:

> Date: Wed, 09 Jun 1999 10:41:02 +0200
> From: Michal Samek <webmaster@tony.cz>
> To: pgsql-sql <pgsql-sql@postgreSQL.org>
> Subject: [SQL] Select like when searching for whole word and optimizing it
> 
> In my e-shop I'm using the searching based on select like command;
> something like
> SELECT * FROM kat WHERE name LIKE '%some_text%';
> and when searching for the whole word:
> SELECT * FROM kat WHERE name LIKE '% some_text %';
> For this is necessary to maintain the name column with one space added
> before and after the name column value (to match starting and ending
> words). It's working but very ugly. 
> 
> Maybe there is some better way to search for the whole word? 
> 
> And another question, is there some way to optimize the SELECT LIKE
> querry? I know that when I send something like "SELECT * FROM kat WHERE
> name LIKE 'blabla%';" postgresql uses the index but not when the search
> string begins with '%'... My table is quickly growing and now I can feel
> the speed of my web is impacted a lot. 
> 
> There is a lot of same values in the name field (for ex. 'QUEEN' about
> 40 times etc.) - I could make a table with unique only name values and
> point to them from the main table kat. Will the searching be more
> effective then? 
> 
> Thanks for any help; I hope it's interesting not only for me :) 
> -- 
> Michal Samek, Tony distribuce s.r.o.
> webmaster@tony.cz  (++420659/321350)
> ICQ: 38607210
> 

_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83