How to speed up “select count(*)” with “group by” and “where”?

Question

How to speed up select count(*) with group by?
It\'s too slow and is used very frequently.
I have a big trouble using select count(*)

Answer 1

If you what the size of the whole table, you should query the meta tables or info schema (that exist on every DBMS I know, but I'm not sure about MySQL). If your query is selective, you have to make sure there is an index for it.

AFAIK there is nothing more you can do.