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Re: Analyze question
Posted by: Dorian Kuroki
Date: July 15, 2010 11:26AM

Ok, thanks for your comments,
but now I have 3 more questions about this.

1. The optimizer is based on statistics, even in those circumstances? Because in my database it can be dangerous ( if the optimizer cardinality are the same that "show indexes from table" )

2. Is true that in innodb "table statistics are updated automatically, so you do not need to run analyze table"? if it is true, the Analyze command is obsolete?

3. What means "Also note MySQL uses index cardinality data only for non-constant join optimization" ? . If I have an inner or outer join then the optimizer acts with cardinality , and not for queries with single table? For exmaple:

Select * from A inner join B on (a.id=b.id) ---> Optimizer consider cardinality
select * from A where id=xx ---> Optimizer NOT consider cardinality

Many thanks

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