please EXPLAIN ANALYZE
Pavel
2010/1/5 Milan Zamazal <pdm@brailcom.org>:
>>>>>> "PS" == Pavel Stehule <pavel.stehule@gmail.com> writes:
>
> PS> please, send explain result
>
> For ~ 10 million rows table:
>
> explain declare c cursor for select * from foo2 order by value;
> QUERY PLAN
> ----------------------------------------------------------------------
> Sort (cost=1829429.20..1854429.20 rows=9999999 width=10)
> Sort Key: value
> -> Seq Scan on foo2 (cost=0.00..154049.99 rows=9999999 width=10)
> (3 rows)
>
> For ~ 1 million rows table, containing the first million rows from foo2
> (`value' column contains random integer data):
>
> explain declare c cursor for select * from foo order by value;
> QUERY PLAN
> -----------------------------------------------------------------------------------
> Index Scan using foo_value_idx on foo (cost=0.00..47604.02 rows=999999 width=10)
> (1 row)
>
> When seqscan is disabled for the 10 million rows table:
>
> set enable_seqscan = off;
> explain declare c cursor for select * from foo2 order by value;
> QUERY PLAN
> -----------------------------------------------------------------------------------------
> Index Scan using foo2_value_idx on foo2 (cost=0.00..32220140.73 rows=9999999 width=10)
> (1 row)
>
> Regards,
> Milan Zamazal
>
>