On Tue, Jan 14, 2014 at 12:07 PM, knizhnik <knizhnik@garret.ru> wrote:
> But is it possible to use index for derived table at all?
Yes, the planner will do an index scan when it makes sense.
> Why sequential search is used for derived table in the example below:
> insert into derived_table values (2,2);
> create index derived_index on derived_table(x);
> explain select * from base_table where x>=0;
With only 1 row in the table, the planner decides there's no point in
scanning the index. Try with more realistic data.
Regards,
Marti