From: | Erik Jones <erik(at)myemma(dot)com> |
---|---|
To: | "Roberts, Jon" <Jon(dot)Roberts(at)asurion(dot)com> |
Cc: | <theo(at)flame(dot)co(dot)za>, <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: Optimizer : query rewrite and execution plan ? |
Date: | 2008-02-06 15:27:33 |
Message-ID: | 6581A916-DA36-4E8E-92DF-48344BB6E1E0@myemma.com |
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Thread: | |
Lists: | pgsql-performance |
On Feb 6, 2008, at 7:35 AM, Roberts, Jon wrote:
>
>>> Since the SQL is not your fault and difficult to control, it is an
>>> argument in favour of an optional planner mode that would perform
>>> additional checks for redundant clauses of various kinds. The
> default
>>> for that would be "off" since most people don't suffer from this
>>> problem. BO isn't the only SQL generating-client out there, so I
> think
>>> this is a fairly wide problem.
>>
>> I would have to disagree. I spend a lot of time writing code that
>> generates SQL from a business app and feel strongly that any
>> optimisation is my responsibility.
>>
>
> The point to a BI tool like BO is to abstract the data collection
> and do
> it dynamically. The SQL is built at run time because the tool is
> designed to give the end user as much flexibility as the data
> structure
> allows to query the data however they want.
>
> It isn't feasible, possible, or recommended to rewrite all of the
> possible generated SQL that could be designed at runtime by the tool.
No, but it is feasible to expect the tool to generate well-formed
queries without redundant clauses. There are plenty that do.
Erik Jones
DBA | Emma®
erik(at)myemma(dot)com
800.595.4401 or 615.292.5888
615.292.0777 (fax)
Emma helps organizations everywhere communicate & market in style.
Visit us online at http://www.myemma.com
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