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* Is index usage in LIKE-queries with UTF-8 implemented in PG-8.3 ?
@ 2007-06-28 14:30 Andreas Joseph Krogh <andreak@officenet.no>
0 siblings, 2 replies; 7+ messages in thread
From: Andreas Joseph Krogh @ 2007-06-28 14:30 UTC (permalink / raw)
To: pgsql-sql
Hi all.
Anybody knows if the following query will use an index-scan in PG-8.3?
SELECT name FROM person WHERE name LIKE 'and%';
I know this works in "C"-locale, but I need it with UTF-8, probably the rest
of the world soon too...
--
Andreas Joseph Krogh <andreak@officenet.no>
Senior Software Developer / Manager
------------------------+---------------------------------------------+
OfficeNet AS | The most difficult thing in the world is to |
Karenslyst Allé 11 | know how to do a thing and to watch |
PO. Box 529 Skøyen | somebody else doing it wrong, without |
0214 Oslo | comment. |
NORWAY | |
Tlf: +47 24 15 38 90 | |
Fax: +47 24 15 38 91 | |
Mobile: +47 909 56 963 | |
------------------------+---------------------------------------------+
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Is index usage in LIKE-queries with UTF-8 implemented in PG-8.3 ?
@ 2007-06-28 14:43 Pavel Stehule <pavel.stehule@gmail.com>
parent: Andreas Joseph Krogh <andreak@officenet.no>
1 sibling, 0 replies; 7+ messages in thread
From: Pavel Stehule @ 2007-06-28 14:43 UTC (permalink / raw)
To: Andreas Joseph Krogh <andreak@officenet.no>; +Cc: pgsql-sql
Hello,
it's possible. You have to use varchar_pattern_ops:
CREATE INDEX like_index ON person(name varchar_pattern_ops);
Regards
Pavel Stehule
2007/6/28, Andreas Joseph Krogh <andreak@officenet.no>:
> Hi all.
> Anybody knows if the following query will use an index-scan in PG-8.3?
>
> SELECT name FROM person WHERE name LIKE 'and%';
>
> I know this works in "C"-locale, but I need it with UTF-8, probably the rest
> of the world soon too...
>
> --
> Andreas Joseph Krogh <andreak@officenet.no>
> Senior Software Developer / Manager
> ------------------------+---------------------------------------------+
> OfficeNet AS | The most difficult thing in the world is to |
> Karenslyst Allé 11 | know how to do a thing and to watch |
> PO. Box 529 Skøyen | somebody else doing it wrong, without |
> 0214 Oslo | comment. |
> NORWAY | |
> Tlf: +47 24 15 38 90 | |
> Fax: +47 24 15 38 91 | |
> Mobile: +47 909 56 963 | |
> ------------------------+---------------------------------------------+
>
> ---------------------------(end of broadcast)---------------------------
> TIP 3: Have you checked our extensive FAQ?
>
> http://www.postgresql.org/docs/faq
>
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Is index usage in LIKE-queries with UTF-8 implemented in PG-8.3 ?
@ 2007-06-28 15:20 Tom Lane <tgl@sss.pgh.pa.us>
parent: Andreas Joseph Krogh <andreak@officenet.no>
1 sibling, 1 reply; 7+ messages in thread
From: Tom Lane @ 2007-06-28 15:20 UTC (permalink / raw)
To: Andreas Joseph Krogh <andreak@officenet.no>; +Cc: pgsql-sql
Andreas Joseph Krogh <andreak@officenet.no> writes:
> Anybody knows if the following query will use an index-scan in PG-8.3?
> SELECT name FROM person WHERE name LIKE 'and%';
> I know this works in "C"-locale, but I need it with UTF-8,
"C locale" and "UTF8" are entirely orthogonal things.
regards, tom lane
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Is index usage in LIKE-queries with UTF-8 implemented in PG-8.3 ?
@ 2007-06-28 15:30 Andreas Joseph Krogh <andreak@officenet.no>
parent: Tom Lane <tgl@sss.pgh.pa.us>
0 siblings, 2 replies; 7+ messages in thread
From: Andreas Joseph Krogh @ 2007-06-28 15:30 UTC (permalink / raw)
To: Tom Lane <tgl@sss.pgh.pa.us>; +Cc: pgsql-sql
On Thursday 28 June 2007 17:20:56 Tom Lane wrote:
> Andreas Joseph Krogh <andreak@officenet.no> writes:
> > Anybody knows if the following query will use an index-scan in PG-8.3?
> > SELECT name FROM person WHERE name LIKE 'and%';
> > I know this works in "C"-locale, but I need it with UTF-8,
>
> "C locale" and "UTF8" are entirely orthogonal things.
>
> regards, tom lane
I had the impression that LIKE-queries of type LIKE '123%' couldn't use an
index if encoding was UTF-8. I was wrong obviously. The varchar_pattern_ops
suggested by Pavel did the trick for me.
Tom: Can you comment on, very short, if the discussion on HACKERS with
title "like/ilike improvements" will improve LIKE queries like this?
Anybody knows if queries of type "LIKE '%234%'" ever will be able to use
indexes, and if someone is working on it? I'm sure I'm not the only one who
would very much appreciate it:-)
--
Andreas Joseph Krogh <andreak@officenet.no>
Senior Software Developer / Manager
------------------------+---------------------------------------------+
OfficeNet AS | The most difficult thing in the world is to |
Karenslyst Allé 11 | know how to do a thing and to watch |
PO. Box 529 Skøyen | somebody else doing it wrong, without |
0214 Oslo | comment. |
NORWAY | |
Tlf: +47 24 15 38 90 | |
Fax: +47 24 15 38 91 | |
Mobile: +47 909 56 963 | |
------------------------+---------------------------------------------+
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Is index usage in LIKE-queries with UTF-8 implemented in PG-8.3 ?
@ 2007-06-28 15:54 Tom Lane <tgl@sss.pgh.pa.us>
parent: Andreas Joseph Krogh <andreak@officenet.no>
1 sibling, 1 reply; 7+ messages in thread
From: Tom Lane @ 2007-06-28 15:54 UTC (permalink / raw)
To: Andreas Joseph Krogh <andreak@officenet.no>; +Cc: pgsql-sql
Andreas Joseph Krogh <andreak@officenet.no> writes:
> Anybody knows if queries of type "LIKE '%234%'" ever will be able to use
> indexes, and if someone is working on it?
Perhaps you are looking for full text search (contrib/tsearch2)?
regards, tom lane
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Is index usage in LIKE-queries with UTF-8 implemented in PG-8.3 ?
@ 2007-06-28 16:14 Andreas Joseph Krogh <andreak@officenet.no>
parent: Tom Lane <tgl@sss.pgh.pa.us>
0 siblings, 0 replies; 7+ messages in thread
From: Andreas Joseph Krogh @ 2007-06-28 16:14 UTC (permalink / raw)
To: pgsql-sql; +Cc: Tom Lane <tgl@sss.pgh.pa.us>
On Thursday 28 June 2007 17:54:59 Tom Lane wrote:
> Andreas Joseph Krogh <andreak@officenet.no> writes:
> > Anybody knows if queries of type "LIKE '%234%'" ever will be able to use
> > indexes, and if someone is working on it?
>
> Perhaps you are looking for full text search (contrib/tsearch2)?
No, I know very well that tsearch2 exists, and use it, but it doesn't
handle "contains" queries.
--
Andreas Joseph Krogh <andreak@officenet.no>
Senior Software Developer / Manager
------------------------+---------------------------------------------+
OfficeNet AS | The most difficult thing in the world is to |
Karenslyst Allé 11 | know how to do a thing and to watch |
PO. Box 529 Skøyen | somebody else doing it wrong, without |
0214 Oslo | comment. |
NORWAY | |
Tlf: +47 24 15 38 90 | |
Fax: +47 24 15 38 91 | |
Mobile: +47 909 56 963 | |
------------------------+---------------------------------------------+
^ permalink raw reply [nested|flat] 7+ messages in thread
* Re: Is index usage in LIKE-queries with UTF-8 implemented in PG-8.3 ?
@ 2007-06-29 07:31 Oleg Bartunov <oleg@sai.msu.su>
parent: Andreas Joseph Krogh <andreak@officenet.no>
1 sibling, 0 replies; 7+ messages in thread
From: Oleg Bartunov @ 2007-06-29 07:31 UTC (permalink / raw)
To: Andreas Joseph Krogh <andreak@officenet.no>; +Cc: Tom Lane <tgl@sss.pgh.pa.us>; pgsql-sql
On Thu, 28 Jun 2007, Andreas Joseph Krogh wrote:
> Anybody knows if queries of type "LIKE '%234%'" ever will be able to use
> indexes, and if someone is working on it? I'm sure I'm not the only one who
> would very much appreciate it:-)
>
This is quite easily could be done with tsearch using substring dictionary.
Search archives !
Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83
^ permalink raw reply [nested|flat] 7+ messages in thread
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Thread overview: 7+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2007-06-28 14:30 Is index usage in LIKE-queries with UTF-8 implemented in PG-8.3 ? Andreas Joseph Krogh <andreak@officenet.no>
2007-06-28 14:43 ` Pavel Stehule <pavel.stehule@gmail.com>
2007-06-28 15:20 ` Tom Lane <tgl@sss.pgh.pa.us>
2007-06-28 15:30 ` Andreas Joseph Krogh <andreak@officenet.no>
2007-06-28 15:54 ` Tom Lane <tgl@sss.pgh.pa.us>
2007-06-28 16:14 ` Andreas Joseph Krogh <andreak@officenet.no>
2007-06-29 07:31 ` Oleg Bartunov <oleg@sai.msu.su>
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