From: Bruce Momjian <maillist@candle.pha.pa.us>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Daniel Kalchev <daniel@digsys.bg>
Cc: pgsql-hackers@postgreSQL.org
Subject: Re: [HACKERS] Postgres 6.5 beta2 and beta3 problem
Date: Wed, 9 Jun 1999 20:51:04 -0400 (EDT)
Message-ID: <199906100051.UAA14533@candle.pha.pa.us> (raw)
In-Reply-To: <29420.928948234@sss.pgh.pa.us>
> LIKE doesn't know anything about indexes, nor vice versa. What the
> index-scan machinery *does* know about is <, <=, etc. If you have
> WHERE clauses like "x >= 33" and "x <= 54" then an index scan knows
> to only scan the part of the index from 33 to 54. So you never even
> visit a large fraction of the table. This is why an index scan can
> be faster than a sequential scan even though the per-tuple overhead
> of consulting the index is larger.
>
You know, everyone beats me up for that LIKE indexing hack, but every
month that goes by where someone does not come up with a better solution
makes me feel a little better about the criticism.
--
Bruce Momjian | http://www.op.net/~candle
maillist@candle.pha.pa.us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
+ Christ can be your backup. | Drexel Hill, Pennsylvania 19026
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To: pgsql-hackers@postgresql.org
Cc: maillist@candle.pha.pa.us, tgl@sss.pgh.pa.us, daniel@digsys.bg
Subject: Re: [HACKERS] Postgres 6.5 beta2 and beta3 problem
In-Reply-To: <199906100051.UAA14533@candle.pha.pa.us>
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