Thread: Fwd: Btree doesn't work with ">" condition

Hi,   I'm testing PostgreSQL, version 7.1.2, and I create a table,  test1, with these kind of fields:

CREATE TABLE test1 (   id integer,   content varchar
);

with 800.000 records, and a btree index setted on the id field.

I noticed the query uses the index for "=" and "<" operators, but if the value used for the "<" operator is higher
(600.000for example), the query makes a seq scan of the table, and the index never works with the ">" operator. Am I
managingthe indexes well ?
 

Thanks for the help.

Ciao Paolo

Paolo Cassago

TalentManager
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On 16 Nov 2001, Paolo Cassago wrote:

>     I'm testing PostgreSQL, version 7.1.2, and I create a table,
> test1, with these kind of fields:
>
> CREATE TABLE test1 (
>     id integer,
>     content varchar
> );
>
> with 800.000 records, and a btree index setted on the id field.
>
> I noticed the query uses the index for "=" and "<" operators, but if
> the value used for the "<" operator is higher (600.000 for example),
> the query makes a seq scan of the table, and the index never works
> with the ">" operator. Am I managing the indexes well ?

Let's go through the standard things. :)  Have you vacuum analyzed
the table?  What does explain show for the queries (particularly the
row count).  If the number of rows grabbed is a reasonable percentage
of the table, currently sequence scan *may* be faster than an index
scan, so this may not be incorrect.