Re: Bypassing useless ORDER BY in a VIEW - Mailing list pgsql-performance

From Tom Lane
Subject Re: Bypassing useless ORDER BY in a VIEW
Date
Msg-id 16851.1204235535@sss.pgh.pa.us
Whole thread Raw
In response to Re: Bypassing useless ORDER BY in a VIEW  ("Dean Gibson (DB Administrator)" <postgresql@ultimeth.com>)
List pgsql-performance
"Dean Gibson (DB Administrator)" <postgresql@ultimeth.com> writes:
> Of course, where ORDER BY in a VIEW is really helpful, is with OFFSET
> and/or LIMIT clauses (which are also PostgreSQL extensions), which is
> equivalent to what you point out.

Right, which is the main reason why we allow it.  I think that these
are sort of poor man's cases of things that SQL2003 covers with
"windowing functions".

The SQL spec treats ORDER BY as a cosmetic thing that you can slap onto
the final output of a SELECT.  They don't consider it useful in
subqueries (including views) because row ordering is never supposed to
be a semantically significant aspect of a set of rows.

            regards, tom lane

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