Re: Query is not using index when it should

On Fri, 10 Dec 2004, Tomas [iso-8859-1] Skre wrote:

> I have a table that looks like this:
>
> Table "public.cjm_object"
> Column | Type | Modifiers
> -----------+-------------------+-----------
> timestamp | bigint | not null
> jobid | bigint | not null
> objectid | bigint | not null
> class | integer | not null
> field | character varying | not null

In 7.4.x and earlier, you need to cast the value you're comparing to into
a bigint in order to make sure the indexes are used (in your timestamp
case it appears to work because the value doesn't fit in a plain integer).
8.0 should handle this better.

> But when doing a search with objectid, class and field, it doesn't use
> the idx_cjm_object1 index.
> db=# explain analyze select * from cjm_object where objectid=4534 and class=12 and field='paroid';

Using one of
objectid=4534::bigint
objectid='4534'
objectid=CAST(4534 as bigint)
rather than objectid=4534 should make this indexable in 7.4.x.