Although I said as following, the gain seems a bit larger... I'll
recheck the testing conditions...
> > Another point here is that the projection code already special-cases
> > simple projections, so it's a bit hard to believe that it's as slow as
> > you suggest above. I wonder if your test case is confusing that
> > optimization somehow.
>
> The whole table is on memory and query is very simple and the
> number of columns is relatively larger in this case. This is
> because I intended to improve retrieving a large part of
> partitioned table with many columns.
--
Kyotaro Horiguchi
NTT Open Source Software Center