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From Dan Karp <dk...@zimbra.com>
Subject Re: IN clause and query plans
Date Sat, 17 Mar 2007 18:20:41 GMT
> I'm seeing some slowness in a query that should be using an index, and
> I'm wondering if it's because Derby's query optimizer hates my use of
> the IN clause.  I'm using 10.2.2 embedded.
> 
> Here's the query and plan with the 78-element IN clause:
> 
> Executing prepared statement: SELECT parent_id, id, unread, flags,
> tags FROM mboxgroup1.mail_item WHERE mailbox_id = ? AND parent_id IN 
> (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?,
> ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?,
> ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?,
> ?, ?, ?, ?, ?, ?, ?, ?, ?) ORDER BY parent_id

Apologies for following up to my own post, but it appears that the 2.5-second execution time
for this query is dwarfed by the 8-second prepare time.  Is that amount of time to prepare
a statement that uses an index, uh, normal?

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