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From Auser99 <guser999...@gmail.com>
Subject Re: Select ... where ... IN (Select ... )
Date Thu, 18 Feb 2010 04:51:03 GMT


Auser99 <guser999000@gmail.com> writes:

>> In Derby, when user Select ... where ... IN (Select  ... ), it runs
>> extremely
>> slow, even though both selects are have optimized indeces (the primary
>> keys). Can someone suggest a get-around rather than run the queries one
>> at a
>> time? Thanks.

> It's difficult to say without seeing the exact query, but sometimes it
> may be faster to write the query as a join instead of using an IN
> subquery. In many cases Derby is able to rewrite the query for you (see
> [1] and [2]), but it doesn't always detect that there is an equivalent
> join.

> [1] http://db.apache.org/derby/docs/10.5/tuning/ctuntransform36368.html
> [2] http://db.apache.org/derby/docs/10.5/tuning/ctuntransform25868.html


Thanks. I'll give it a try.

http://www.xprad.org/

gu

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