Re: Statistics used by optimizer.

[Rakshit Trivedi]

Hi,

Got your point. Thanks for the quick reply. I had one more question regarding the index access or you can say the no. of rows estimated for InnoDB engine.

As explained by you, for InnoDB engines,it probes 10 random spots in the table whenever you 'open' the table. So how this random probing works? I mean to ask how the no of rows to be read are estimated using these 10 different probes?

Moreover, is this probing done for each and every query. I mean how this probing works when we explain the same query with different constants (values)?

I event went through the open source code but could not exactly get answer to these questions. So it would be great help if you can locate me in the code wherein I can find this implementation.

Thanks.