Re: Group-wise Maximum performance

[Felix Geerinckx]

Jon Richards wrote:

> explain SELECT data from storm s1 where
> time=(select max(s2.time) from storm s2 where
> s1.name = s2.name);
>
> with 360 updates to 20 objects with the same name
> gives:
>
> "id","select_type","table","type","possible_keys",
> "key","key_len","ref","rows","Extra"
> 1,"PRIMARY","s1","ALL","","",(null),"",6973,"Using
> where"
> 2,"DEPENDENT
> SUBQUERY","s2","ref","PRIMARY","PRIMARY",255,"stor
> m.s1.name",1,"Using index"

Definitely try a seperate index on your time column.
P.S.: why are you using a bigint for your time column?

--
felix