Re: Screwy Statistics...

VACUUM ANALYZE then do the same you will get the results you are looking
for.

Darren
On Fri, 6 Sep 2002, Glen Parker wrote:

> First, shouldn't statistics have some clue how many rows
> might be in the table, at least right after an analyze?
>
> Second, if the planner believes it will find 6700 rows in a
> 35000 row table, shouldn't it choose an index?  I have a
> unique index on "branch".  What percentage of expected
> rows/possible rows is the usual cutoff, anyone know?
> Whatever it is, it seems too low to me.
>
>
> oms=# select version();
>                            version
> -------------------------------------------------------------
>  PostgreSQL 7.2.1 on i686-pc-linux-gnu, compiled by GCC 2.96
> (1 row)
>
> oms=# analyze items;
> ANALYZE
>
> oms=# select count(*) from items;
>  count
> -------
>  34865
> (1 row)
>
> oms=# explain select * from items where branch='10';
> NOTICE:  QUERY PLAN:
>
> Seq Scan on items  (cost=0.00..3588.70 rows=46546 width=520)
>
> EXPLAIN
>
> oms=# explain select * from items where branch='30';
> NOTICE:  QUERY PLAN:
>
> Seq Scan on items  (cost=0.00..3588.70 rows=6710 width=520)
>
> EXPLAIN
>
>
> Glen Parker
> glenebob@nwlink.com
>
>
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>

--
Darren Ferguson