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Re: Problems with system locking
Posted by: Ingo Strüwing
Date: May 15, 2006 02:57AM

Hi Brian,

Brian O'Donnell wrote:
...
> I guess MySQL will go and examine all the
> underlying tables for each query?
>
> We were thinking that if we set the MERGE table to
> use the first table
...
> However I'm not sure this will
> make any difference as it probably has to go to
> the other tables to ensure the data isn't in them
> - unless it builds a separate index?

MERGE cannot make any assumptions about the contents of the tables. It has to scan all indexes.

But you can create multiple MERGE tables. Create one for the last two tables, one for the last three, and so on, whatever you need.

Regards

Ingo Strüwing, Senior Software Developer - Storage Engines
MySQL AB, www.mysql.com

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