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Re: index is not used why?
Posted by: Rick James
Date: March 24, 2009 08:11PM

* ROW_FORMAT=FIXED is much overrated. If your rows vary in width even a little, you save disk space by letting it be DYNAMIC. This leads to better caching which leads to being faster.

* Yeah, in a few selected cases, multiple indexes will be used. But it is not all cases.

* The selects weren't faster? Did you add the index I recommended:
KEY (n_group_id)
and make this change
KEY (`n_resource_id`,`n_group_id`, c_id) -- field added

* "Why does MySQL think to scan all rows instead using the key?" There are lots of reasons. Here is one:,253989,254168

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Written By
March 18, 2009 05:32AM
March 19, 2009 07:45PM
March 24, 2009 08:15AM
Re: index is not used why?
March 24, 2009 08:11PM
March 24, 2009 08:34PM

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