Re: query not using index

On Mon, 3 Sep 2001, Norbert Zoltan Toth wrote:

> Hi,
>
> I have created the following test table:
> create table history (event_id int8 not null, event_type int, event_name
> char(10), event_ts timestamp, user_data_ref int8);
>
> I've populated the table with 20,000,000 rows.
>
> I have created an index table:
> create index history_idx on history (event_id);
>
> When I issue the following query, it takes about 6 minutes:
> select event_id from history where event_id = 1;
>
> I have run vacuum, vacuum analyze but it had no effect on the speed.
> Explain sais the followings:
>
> explain select event_id from history where event_type = 120;
> NOTICE: QUERY PLAN:
>
> Seq Scan on history (cost=0.00..446079.00 rows=200000 width=8)
>
> even if I do a drop index history_idx, explains sais the same.

You need to make the constant be seen as an int8. IIRC, you can either do
this by quoting the number '120' or by doing an explicit cast in the
query. See past discussions on -general and -hackers in the archives.