From: Olivier Hubaut <olivier@scmbb.ulb.ac.be>
To: pgsql-sql@postgresql.org
Subject: Re: INDEX and LIKE
Date: Mon, 29 Nov 2004 14:45:42 +0100
Message-ID: <opsh8a6gzu94ope3@olivier.amaze.ulb.ac.be> (raw)
In-Reply-To: <41AB13C0.40909@numerixtechnology.de>
References: <41AB13C0.40909@numerixtechnology.de>
On Mon, 29 Nov 2004 12:19:12 +0000, T E Schmitz
<mailreg@numerixtechnology.de> wrote:
> Hello,
>
> I need to be able to perform wildcard searches on a VARCHAR(100) column
> of the form
>
> SELECT * FROM item WHERE serial_no LIKE '%12345678%'
>
> Would an index on serial_no do anything at all for this search?
>
No, It wouldn't. If you use "%" for the beginning of you search pattern, a
seqential search is performed, ignoring the index wich use the beginning
of the string in order to create it's B-tree.
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To: pgsql-sql@postgresql.org
Cc: olivier@scmbb.ulb.ac.be
Subject: Re: INDEX and LIKE
In-Reply-To: <opsh8a6gzu94ope3@olivier.amaze.ulb.ac.be>
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