Re: Optimizer : query rewrite and execution plan ?

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От Roberts, Jon
Тема Re: Optimizer : query rewrite and execution plan ?
Дата
Msg-id 1A6E6D554222284AB25ABE3229A92762715551@nrtexcus702.int.asurion.com
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Ответ на Re: Optimizer : query rewrite and execution plan ?  (Erik Jones <erik@myemma.com>)
Список pgsql-performance
> >
> >>> 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.
>


Agreed.


Jon

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