Re: index not being used

You're missing an analyze step: (see below)

>here is the table structure:
>create table test_10million (
>id   int8,
>app_id  int8
>);
>
>< fill the table with 10 million record >
>
>create index test_10million_id on test_10million (id);

ANALYZE test_10million;

>this query always uses sequential scan:
>select * from test_10million where id = 123 and app_id = 100;

Now try

explain select * from test_10million where id = 123 and app_id = 100;

Cheers,

Doug