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.
Exactly the same thing happens if I create this table with event_id int8
primary key.
Since I don't think, that sequential scan is better then index scan in this
case,
could someone tell me why my index is not being used (- and still I'm
getting only 200000 rows scanned - )?
Thanks,
Norbert