Robert A. Crawford wrote:
>
> On Wed, May 26, 1999 at 04:18:23PM +0200, kai@stripped wrote:
> > A index on a single columns will not be used (according to EXPLAIN),
> > nevertheless there is a perfect index for the query. The command
> > explain select * from Tab2 where ColA=2;
> > (index on ColA) produces the following output:
> >
> > table type possible_keys key key_len ref rows Extra
> > Tab2 ALL ColA NULL NULL NULL 3 where used
> >
> > (I expected that key would be ColA instead of NULL.)
> >
> > Since the access to the data is fast, I suspect that the index is used,
> > but will not be used by the EXPLAIN command.
>
> It is likely the number of rows in the table helps
> the optimizer decide whether or not to use the index. I can't
> confirm this, but I've seen the same thing.
>
Consider it confirmed! :)
jim...
