Re: UTF8MatchText

From: Andrew Dunstan <andrew(at)dunslane(dot)net>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Dennis Bjorklund <db(at)zigo(dot)dhs(dot)org>, ITAGAKI Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp>, Bruce Momjian <bruce(at)momjian(dot)us>, pgsql-patches(at)postgresql(dot)org
Subject: Re: UTF8MatchText
Date: 2007-05-20 21:58:32
Message-ID: 4650C488.4060202@dunslane.net
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Tom Lane wrote:
> Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
>
>> Yeah, quite possibly. I'm also wondering if we are wasting effort
>> downcasing what will in most cases be the same pattern over and over
>> again. Maybe we need to look at memoizing that somehow, or at least test
>> to see if that would be a gain.
>>
>
> Someone (Itagaki-san IIRC) suggested that we ought to convert
> "x ILIKE y" into "lower(x) LIKE lower(y)" at some fairly early
> stage, definitely before constant-folding in the planner. That
> would take care of that issue without any run-time mechanism,
> and would open opportunities for making use of an index on lower(x).
>
> I recall thinking at the time that there were some potential downsides,
> but right at the moment I'm darned if I can see any --- especially
> if we're going to make ILIKE do this uniformly at runtime anyway.
>
>
>
Sounds like a TODO item. I'm already concerned a bit about scope creep
for this item.

cheers

andrew

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