| From: | Marti Raudsepp <marti(at)juffo(dot)org> |
|---|---|
| To: | knizhnik <knizhnik(at)garret(dot)ru> |
| Cc: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Inheritance and indexes |
| Date: | 2014-01-14 11:33:32 |
| Message-ID: | CABRT9RASyXyeN2H2ffs-vqPP-LJHeGkuyAKk3wk0hcYt8zOTJQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Jan 14, 2014 at 12:07 PM, knizhnik <knizhnik(at)garret(dot)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
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