Re: Indexscan is only used if we use "limit n"

Sebastián Baioni escribió:
> Hello,
> Whe are running PostgreSQL 8.2.0 on amd64-portbld-freebsd6.2, compiled by GCC cc (GCC) 3.4.6 [FreeBSD] 20060305.
> The query only uses the index if we have a "limit n":

> Without "Limit n"
> explain
> select esapcuit, esapcuil
> from esact00 t1
> order by esapcuit, esapcuil
>
> Sort  (cost=843833.82..853396.76 rows=3825177 width=30)
>   Sort Key: esapcuit, esapcuil
>   ->  Seq Scan on esact00 t1  (cost=0.00..111813.77 rows=3825177 width=30)

That's right.  What else did you expect?  It estimates it has to return
3 million rows after all -- using an indexscan would be slow.

--
Alvaro Herrera                 http://www.amazon.com/gp/registry/DXLWNGRJD34J
"Puedes vivir solo una vez, pero si lo haces bien, una vez es suficiente"