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- Posted on
September 29, 2005, 7:15 pm
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There are 9 indexes on this table.
SHOW INDEX FROM TRAN;
Returns results as expected with all indexes some valid "Cardinality"
After a period of time or a series of events (unknown to me) the statistics
for one or more indexes shows a NULL value in the cardinality.
This causes queries that rely on these indexes to become incredibly slow,
sometimes doing a full table read.
I have been trying to find out what causes the statistics to become NULL?
Any help here would be appreciated.
I currently have a nightly process that scans for NULL table statistics then
updates (analyze table) any table effected.
Thank you for any help!
Re: Database statistics / cardinality - NULL problem
What version of MySQL are you using?
I see a bug (http://bugs.mysql.com/bug.php?id=2019) that matches this
issue, but it's reported against MySQL 3.23, and the response is "Won't
Fix" because that release it so far out of date.
If you can reproduce the behavior on the latest MySQL 4.1 or 5.0
releases, I'd recommend filing a bug at bugs.mysql.com.
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