Re: Index usage question

What does your data look like? If you have a lot of duplicate id's, a
sequential scan may be better than an index scan.
If you are not sure if this is the case, try:

SELECT id, count(*) AS count FROM test GROUP BY id ORDER BY count DESC
LIMIT 50;

This should show you the top 50 most duplicated records in your table.

-r

At 08:52 PM 9/4/01 +0200, Norbert Zoltan Toth wrote:

>I have experienced the following problem, maybe they are related:
>
>I create a table with
> create table test (id int, name char(10));
>
>then I create an index on it with
> create index test_idx on test (id);
>
>After populating my table, the query
> select id from test where id='1';
>
>uses index scan.
>
>However when I only create the index AFTER inserting rows into the table,
>the index is not being used for the evaluation,
>even if I run vacuum / vaccum analyze on test;
>
>I would also appreciate some help with this.
>
>Thank you,
>Norbert
>
>
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