On Friday, May 17, 2013 4:22 AM Bruce Momjian wrote:
> On Thu, May 16, 2013 at 06:49:33PM -0400, Tom Lane wrote:
> > "'Bruce Momjian'" <bruce@momjian.us> writes:
> > > On Thu, May 16, 2013 at 08:38:59PM +0530, Amit Kapila wrote:
> > >> Reduce query processing overhead by avoiding insertion of useless
> plan nodes
> > >> OR
> > >> Improve performance of certain kind of queries by avoiding extra
> processing
> > >> of doing projection
> > >>
> > >> This applies to queries doing identity projection ("SELECT * FROM
> ...") for
> > >> partitioned tables.
> >
> > > Uh, that's pretty complex for our release notes, and hard to
> understand
> > > for most users. All they will know is that PG is faster --- we
> don't
> > > document every speedup.
> >
> > No, but this is user-visible if they look at EXPLAIN output, and
> people
> > might wonder why they were getting different results.
> >
> > Possibly text like
> >
> > Omit unnecessary Result and Limit nodes from query plans.
>
> Yes, that would be user-visible, though we rarely add details like
> that.
> What queries are faster, that users would understand?
Example:
CREATE TABLE tbl_parent (c01 numeric, c02 int);
CREATE TABLE tbl_child () INHERITS(tbl_parent);
INSERT INTO tbl_child (SELECT floor(random() * 10000), n FROM
generate_series(0, 10000000 - 1) n);
SELECT * FROM tbl_parent;
Any such cases where user is selecting more number of columns from parent
table will improve a lot.
With Regards,
Amit Kapila.
