Re: LIKE operator and indexes

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От Stephan Szabo
Тема Re: LIKE operator and indexes
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Msg-id 20020531095711.V56129-100000@megazone23.bigpanda.com
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Ответ на LIKE operator and indexes  ("Marc Mitchell" <marcm@eisolution.com>)
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On Fri, 31 May 2002, Marc Mitchell wrote:

> Can anyone provide definitive information and/or points of reference within
> the documentation about the ability of the query optimizer to use indexes
> when processing a "LIKE" operator on a String column?
>
> My assumption is that
>
> "SELECT * FROM customer WHERE name LIKE 'GENERAL%';"
>
> should benefit from the existence of a BTREE index on the "customer.name"
> column.  I know this is the case is most other RDBMS's I've used including
> Postgres's ancestor Ingres.

If you are in "C" locale, and have an anchored like or regex, indexes
should be considered.  If you're in a different locale, the optimization
is turned off.


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