Re: Possible solution for LIKE optimization

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Giles Lean <giles(at)nemeton(dot)com(dot)au>
Cc: Peter Eisentraut <peter_e(at)gmx(dot)net>, PostgreSQL Development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Possible solution for LIKE optimization
Date: 2001-08-06 22:21:48
Message-ID: 24902.997136508@sss.pgh.pa.us
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Giles Lean <giles(at)nemeton(dot)com(dot)au> writes:
> Implementations of strxfrm() that I've looked at have had result data
> that is three or four times larger than then input string -- quite a
> penalty in some situations.

Especially so given that we don't have TOAST for indexes, so the indexed
value can't exceed about 2700 bytes (for btree and an 8K block size).
You are allowed to compress first, so that's not a hard limit, but it
could still be a problem.

I like the non-locale-aware-opclass idea much better than the original.

regards, tom lane

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