Re: [PORTS] Port Bug Report: Incorrect search using 'select .... like ...' statement.

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POSTGRESQL BUG REPORT TEMPLATE
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Your name : Misha Yakin
Your email address : misha(at)libr-115c(dot)ksu(dot)ru

Category : runtime: back-end: SQL
Severity : serious

Summary: Incorrect search using 'select .... like ...' statement.

System Configuration
--------------------
Operating System : Linux 2.2.3 ELF(Red Hat 5.0)

PostgreSQL version : 6.4.2

Compiler used : gcc 2.7.2.3

Hardware:
---------
Pentium 166, 32M RAM.

uname -a:
Linux libr-115c.ksu.ru 2.2.3 #1 12 17:09:04 MSK 1999 i586 unknown

Versions of other tools:
------------------------
GNU Make version 3.76.1, flex version 2.5.4,
gcc version 2.7.2.3, glibc 2.0.7

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Problem Description:
--------------------
Sometimes expresion like 'select a from b where a like 'abc%';' gives
null result, while 'select a from b where a like 'abcd%';' gives
right result (several records). In some case first expression
gives some result but it doesn't contains result of the second
one... But expresion '... like 'ab%';' gives result containing
results of the first an the second.

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Test Case:
----------
All fields I tried contain russian characters (there was some
fields with english characters but I don't find such error with them)

example:

vkuzmina=> select tit from cvcat where lower(tit) like '%';
tit
-----------------

(1 row)

vkuzmina=> select tit from cvcat where lower(tit) like '%';
tit
---
(0 rows)

vkuzmina=> select tit from cvcat where lower(tit) like '%';
tit
-----------------

(1 row)

vkuzmina=> select tit from cvcat where tit like '%';
tit
-----------------

(1 row)

vkuzmina=> select tit from cvcat where tit like '%';
tit
---
(0 rows)

vkuzmina=> select tit from cvcat where tit like '%';
tit
-----------------

(1 row)

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Solution:
---------

--------------------------------------------------------------------------

> Sometimes expresion like 'select a from b where a like 'abc%';' gives
> null result, while 'select a from b where a like 'abcd%';' gives
> right result (several records). In some case first expression
> gives some result but it doesn't contains result of the second
> one... But expresion '... like 'ab%';' gives result containing
> results of the first an the second.
>
> --------------------------------------------------------------------------
>
> Test Case:
> ----------
> All fields I tried contain russian characters (there was some
> fields with english characters but I don't find such error with them)
>
>
> example:
>
> vkuzmina=> select tit from cvcat where lower(tit) like '%';
> tit
> -----------------
>
> (1 row)
>
> vkuzmina=> select tit from cvcat where lower(tit) like '%';
> tit
> ---
> (0 rows)
>
> vkuzmina=> select tit from cvcat where lower(tit) like '%';
> tit
> -----------------
>
> (1 row)
>
> vkuzmina=> select tit from cvcat where tit like '%';
> tit
> -----------------
>
> (1 row)
>
> vkuzmina=> select tit from cvcat where tit like '%';
> tit
> ---
> (0 rows)
>
> vkuzmina=> select tit from cvcat where tit like '%';
> tit
> -----------------
>
> (1 row)
>

We have some problems with international characters sets and index
usage. Someone else will probably give a better answer.

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