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Thread: Like vs '='

Like vs '='

From
m w
Date:
I have a function to transform text into a
pseudo-metaphone variable, take this
example:

cddbsql=# select song, metatext(song) from cdsongs
where metatext(song) like
metatext('born to run') limit 3 ;   song     | metatext
-------------+----------Born To Run | brntornBorn To Run | brntornBorn To Run | brntorn
(3 rows)

Here is the problem: Depending on whether there is an
index or not, 'like'
behaves differently. Here is a transcript:

cddbsql=# select song, metatext(song) from cdsongs
where metatext(song) like
metatext('born to run') limit 1 ;   song     | metatext
-------------+----------Born To Run | brntorn
(1 row)
cddbsql=# create index cdsongs_meta_song on cdsongs
(metatext(song)) ;
CREATE
cddbsql=# select song, metatext(song) from cdsongs
where metatext(song) like
metatext('born to run') limit 1 ;song | metatext
------+----------
(0
rows)     

This happens in both 7.0 and
7.1.

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Re: Like vs '='

From
m w
Date:
In 7.1 the row limit is not as big a deal because of
tuple toaster. I had a 7.0 database that needed the
row limit change, in 7.1 it does not seem too.

But if you want to chang it anyway, in config.h, look
for this line:

#define BLCKSZ  8192

It can be made as large as 32768.


--- Manuel Cabido <manny@msuiit.edu.ph> wrote:
> Hi there,
> 
>    I am compiling postgresql 7.1beta4. How would i
> change the default 8k
> row limit? 
> 
> -- 
>                               Manny C. Cabido
>                              
> ====================================
>                              
> e-mail:manny@tinago.msuiit.edu.ph
>                                     
> manny@sun.msuiit.edu.ph
>                              
> =====================================
> 


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Re: Like vs '='

From
Manuel Cabido
Date:
Hi there,
  I am compiling postgresql 7.1beta4. How would i change the default 8k
row limit? 

--                              Manny C. Cabido                             ====================================
                    e-mail:manny@tinago.msuiit.edu.ph                                    manny@sun.msuiit.edu.ph
                    =====================================

Re: Like vs '='

From
"Mitch Vincent"
Date:
There isn't any row or query size limit in 7.1 thanks to TOAST! 

-Mitch


----- Original Message ----- 
From: "Manuel Cabido" <manny@msuiit.edu.ph>
To: "m w" <mttf2000@yahoo.com>
Cc: <pgsql-hackers@postgresql.org>
Sent: Monday, January 29, 2001 10:18 PM
Subject: Re: Like vs '='


> Hi there,
> 
>    I am compiling postgresql 7.1beta4. How would i change the default 8k
> row limit? 
> 
> -- 
>                               Manny C. Cabido
>                               ====================================
>                               e-mail:manny@tinago.msuiit.edu.ph
>                                      manny@sun.msuiit.edu.ph
>                               =====================================
> 
>