[GENERAL] indices don't make much difference

[admin]

I am trying to optimise a query which looks like:
select prod_base.*, manu_base.name from prod_base, manu_base where
prod_base.mid=manu_base.mid;

manu_base is a table consisting of 3000 manufacturer with an id (not
unique to support synonyms) and a name (declared as varchar(32)).
prod_base is a table of products which each refer to the manufacturer id
(mid).

I have tried creating an index for manu_base using the following commands:
create index manu_mid_idx on "manu_base" using btree ("mid" "int2_ops");
drop index manu_mid_idx
create index manu_mid_idx on "manu_base" using hash ("mid" "int2_ops");
drop index manu_mid_idx

I have then run benchmarks without index, with btree and with hash, but
none seem to be faster than the other. My benchmark program is written in
c and is attached to this email. Here are the results I obtained using
time:

without index:
17.25 real  1.42 user  0.26 sys
with btree:
17.28 real  1.38 user  0.30 sys
with hash:
17.22 real  1.37 user  0.32 sys

If there is any way to make a query quicker when joining a product table
and a manufacturer table, please let me know. I've tried everything and
the results are quite fast enough.

Thanks,
Marc

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "libpq-fe.h"

static void exit_nicely(PGconn *conn) {
    PQfinish(conn);
    exit(1);
}

int main() {
    int i, j;
    char *dbName = "wtbwts";

    PGconn *conn;
    PGresult *res;

    conn = PQsetdb(NULL, NULL, NULL, NULL, dbName);

    if (PQstatus(conn) == CONNECTION_BAD) {
        fprintf(stderr, "Connection to database '%s' failed.\n", dbName);
        fprintf(stderr, "%s", PQerrorMessage(conn));
        exit_nicely(conn);
    }

    for (i=0; i<50; i++) {
        res = PQexec(conn, "SELECT prod_base.*, manu_base.name FROM prod_base, 
manu_base where prod_base.mid = manu_base.mid");
        if (!res || PQresultStatus(res) != PGRES_TUPLES_OK) {
            fprintf(stderr, "SELECT failed\n");
            PQclear(res);
            exit_nicely(conn);
        }
        for (j=0; j<PQntuples(res); j++) {
            PQgetvalue(res, j, 0);
        }
        PQclear(res);
    }
    PQfinish(conn);
    return 0;
}