Subject Re: [firebird-support] SQL - performance
Author Martijn Tonies
> > > The second query has an expression for its search operand, ruling out
> > > of the index (for now...expression indices are coming...but the
> > > index would have to exist).
> >
> >On the other hand, a substring(1, x) could be converted to a
> >STARTING WITH as well :-)
> >
> >No need for expression indices there.
> Could be converted to choc-dipped candy, too...but isn't.

Sweeeeeet ;-)

The reason I wrote that, is that expression indices aren't needed
for this to be optimized.

I'm not fully aware of what expression indices should be able
to do anyway. I picture usage as UPPER(column) = 'value'
and an Upper(Column) index...

With regards,

Martijn Tonies
Database Workbench - developer tool for InterBase, Firebird, MySQL & MS SQL
Upscene Productions