Re: Small change needed to support Greenplum DB

Luke Lonergan wrote:
> Hi all,
>
> A customer of ours is using pgAgent with Greenplum Database and needs a
> change to one of the queries used by pgAgent to allow it to work with
> Greenplum.
>
> Here is the conversation:
> _http://groups.google.com/group/pgsql.bugs/browse_thread/thread/27866354fa4d7a5e/60e6e5de3c5156d4#60e6e5de3c5156d4
>
> _The problem is that Greenplum does not support some correlated
> subqueries, so Jon created a version of the query that is both faster
> and does not use a correlated subquery.
>
> The requested change is from this in pgaJob.cpp:

Hi Luke,

Does Greenplum support DISTINCT ON? Specifically,

SELECT j.*, cl.*, ag.*, sub.jlgstatus
FROM pgagent.pga_job j JOIN
pgagent.pga_jobclass cl ON cl.jclid=jobjclid LEFT OUTER JOIN
pgagent.pga_jobagent ag ON ag.jagpid=jobagentid JOIN
(SELECT DISTINCT ON (jlgjobid) jlgstatus, jlgjobid
FROM pgagent.pga_joblog
ORDER BY jlgjobid, jlgid desc) sub ON sub.jlgjobid = j.jobid
-- + restriction +
ORDER BY jobname;

Regards, Dave.