CODEWITHSUNDEEP
mysqlmyisam
Bart
Bart

Reputation: 6814

Why did my MySQL Index Cardinality get Zeroed out?

I have an older web application that uses a MySQL Database (MYISAM). I noticed recently that the performance of the application was drastically reduced. After checking on my indexes, I noticed that the cardinality for all of them was reporting zero.

I was able to fix this by doing an ANALYZE TABLE on each table.

But I'm curious, what causes the cardinality to get zeroed out in the first place?

Upvotes: 4

Views: 661

Answers (1)

Morgan Tocker
Morgan Tocker

Reputation: 3438

From memory, some repair table operations wipe the statistics and you need to ANALYZE TABLE to get them back.

Other than that, I can't think of any reason why they should be zeroed. I'd just expect that they'd be out of date.

Upvotes: 3

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