Why did my MySQL index database get a null value?

Question

I have an older web application using MySQL database (MYISAM). I recently noticed that application performance has dropped dramatically. After checking my indices, I noticed that the power for all of them was zero.

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

But I'm curious what leads to the fact that the power is first reset to zero?

Answer 1

From memory, some operations in the repair table destroy statistics, and you need to perform ANALYZE TABLE to return them.

In addition, I can’t think of why they should be reset. I would just expect them to be out of date.