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From: John R Pierce <pierce@hogranch.com>
To: pgsql-general@postgresql.org
Subject: Re: Checkpoint_segments optimal value
Date: Thu, 17 Jul 2014 16:51:33 -0700
Message-ID: <53C86185.2020506@hogranch.com> (raw)
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On 7/17/2014 11:28 AM, Prabhjot Sheena wrote:
>
> SELECT account.id <http://account.id;, account.organization_id, 
> run.application_id, work_unit.script, work_unit.id 
> <http://work_unit.id;, work_unit.start_time, run.id <http://run.id;, 
> work_unit.priority  FROM work_unit, run, account  WHERE  
> work_unit.status = 3 AND work_unit.run_id = run.id <http://run.id; AND 
> work_unit.type != 1 AND run.status = 1 AND run.account_id = account.id 
> <http://account.id;

that query is an implied 3-way join.  it would be clearer to write it 
like...

SELECT account.id <http://account.id;, account.organization_id, 
run.application_id, work_unit.script, work_unit.id 
<http://work_unit.id;, work_unit.start_time, run.id <http://run.id;, 
work_unit.priority
     FROM work_unit
         JOIN run ON work_unit.run_id = run.id <http://run.id;
         JOIN account  ON run.account_id = account.id <http://account.id;
     WHERE work_unit.status = 3 AND work_unit.type != 1 AND run.status = 1;

postgres would (or at least should) treat this exactly the same, but its 
clearer what the query is doing when its written this way.


-- 
john r pierce                                      37N 122W
somewhere on the middle of the left coast

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