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Non-C locale and LIKE

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: PostgreSQL-development <pgsql-hackers(at)postgreSQL(dot)org>
Subject: Non-C locale and LIKE
Date: 2004-11-28 04:52:56
Message-ID: 200411280452.iAS4quv12028@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
I know we can't currently use an index with non-C locales and LIKE
except when we create a sepcial type of index for LIKE indexing
(text_pattern_ops).

However, I am wondering if we should create a character lookup during
initdb that has the characters ordered so we can do:

	col LIKE 'ha%' AND col >= "ha" and col <= "hb"

Could we do this easily for single-character encodings?  We could have:

	A	1
	B	2
	C	3

and a non-C locale could be:

	A	1
	A`	2
	B	3

We can't handle multi-byte encodings because the number of combinations
is too large or not known.

Also, we mention you should use the "C" locale to use normal indexes for
LIKE but isn't it more correct to say the encoding has to be SQL_ASCII?

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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Subject: Re: Non-C locale and LIKE
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