Re: Index not used in functions in 7.0?

mig(at)utdt(dot)edu wrote:

> I am probably completely wrong, but at least it will be short ...
>
> Could it be that
> select sum(tquant)
> from mtr_reg
> where to_proj = $2
> and pnum = $1
> and (status = 'clsd' or status = 'open' or status = 'prip')
> ;
> makes it harder for the optimizer due to the ORs, and that
> select sum(tquant)
> from mtr_reg
> where to_proj = $2
> and pnum = $1
> and status in ('clsd','open','prip')
> --- last line changed
> ;
> would produce a better cost estimate?
>
> Miguel Sofer

Thanks for the input. Your point might be correct, but my results are
the same regardless of the clause attached to the status field. In one
of my tests, the query simply had "and status = 'clsd'." The issue here
is that a sequential scan is being chosen over an indexed scan when the
query is run from within a function.