Re: Learning to read explain

On Fri, 30 Nov 2001, Rob Arnold wrote:

> I too would like help on this subject.

It seems a common issue for newbies, yet I don't see any docs on the
subject. Maybe there are, I just don't know where they are.

> Here is the little bit I know (or think I know):

Thanks for the info.

If I do eventually get to understand "explain", I may try and write
something up. One of the most common questions has to be "why is such
query so slow". Many times is just a matter of an index not been used or
not been present at atll. Sometimes, however, even when there is an index
the optimizer doesn't use the index and the user asks itself why. I think
that "explain" would have the answer if one knew how to read it.