Re: PostgreSQL doesn't use indexes even is enable_seqscan

Postgres thinks 300000 is an int4 and not int8 so it is not using the
index on the int8.

Either cast by doing

EXPLAIN SELECT * FROM one WHERE id = 300000::bigint;

or

EXPLAIN SELECT * FROM one WHERE id = '300000';

Darren

On Sun, 7 Jul 2002, Hans-Juergen Schoenig wrote:

> I have a severe problem with PostgreSQL 7.2.1.
> I have a table containing 500mio records (for testing purposes).
>
> I have indexed the table:
>
> CREATE UNIQUE INDEX idx_one_id ON one(id);
> CREATE INDEX idx_one_xmod ON one(xmod);
>
> The index was created properly but somehow it isn't used:
>
> cluster=# \d one
>           Table "one"
>   Column |  Type   | Modifiers
> --------+---------+-----------
>   id     | bigint  |
>   even   | boolean |
>   xmod   | integer |
> Indexes: idx_one_xmod
> Unique keys: idx_one_id
>
> cluster=# SET enable_seqscan TO off;
> SET VARIABLE
> cluster=# SELECT * FROM one WHERE id=300000;
> Cancel request sent
> ERROR:  Query was cancelled.
> cluster=# EXPLAIN SELECT * FROM one WHERE id=300000;
> NOTICE:  QUERY PLAN:
>
> Seq Scan on one  (cost=100000000.00..109434714.00 rows=1 width=13)
>
> EXPLAIN
> cluster=# SELECT version();
>                             version
> -------------------------------------------------------------
>   PostgreSQL 7.2.1 on i686-pc-linux-gnu, compiled by GCC 2.96
> (1 row)
>
> When sequential scans are turned off PostgreSQL should use an index but
> it doesn't.
> Is it a bug? Have I done something one?
> Did anybody face a similar problem?
>
>     Hans
>
>
>
>
>
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--
Darren Ferguson