Re: How to force the parser to use index scan instead of sequential scan

On 6 Oct 2006 22:32:16 -0700, ck <ck(dot)karthic(at)gmail(dot)com> wrote:
> Hello,
>
> I am using PostgreSQL 7.3.2. I have a large table in a

that's very old... you should upgrade at least to 7.3.15

> database , its primary key field is int8.
> Almost all of my queries are written relaing to that field. That field
> is B-Tree indexed. When i check the query plan i found that all the
> queries are using sequential scan and index was not used. So my queries
> are likely to be slow. But when i tried to convert the values given to
> that field to int8 in a where condition then the parser is using the
> index scan, Eg
> select * from h057 where h057001 = 1142::int8
> the above query uses index scan
> select * from h057 where h057001 = 1142
> the above query uses sequential scan.

that's because in 7.3 you must cast to the type of the indexed column
in order to use the indexes...

had you never seen this?

TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match

upgrade

--
regards,
Jaime Casanova

"Programming today is a race between software engineers striving to
build bigger and better idiot-proof programs and the universe trying
to produce bigger and better idiots.
So far, the universe is winning."
Richard Cook