Server status query problem

Hi Andreas,

It was pointed out to me that the server status lock tab doesn't show data
correctly - specifically, the username is always blank, and the query string
normally shows up as <backend information unavailable>.

It seems the cause is that most of the stats functions don't take a PID as
an argument, but a backend ID between 1 and the current number of backends.

A hacked together replacement query looks like the following, but before I
appy it I just wanted to run it past you and the list in case I missed
anything:

SELECT
(SELECT datname FROM pg_database WHERE oid = pgl.database) AS dbname,
pgl.relation::regclass AS class,
pg_get_userbyid(pg_stat_get_backend_userid(svrid)) as user,
pgl.transaction,
pg_stat_get_backend_pid(svrid) AS pid,
pgl.mode,
pgl.granted,
pg_stat_get_backend_activity(svrid) AS current_query
FROM
pg_stat_get_backend_idset() svrid,
pg_locks pgl
WHERE
pgl.pid = pg_stat_get_backend_pid(svrid)
ORDER BY
pid;

Regards, Dave