Re: Implement targetlist SRFs using ROWS FROM() (was Changed SRF in targetlist handling)

From: Kevin Grittner <kgrittn(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Andres Freund <andres(at)anarazel(dot)de>, Robert Haas <robertmhaas(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Implement targetlist SRFs using ROWS FROM() (was Changed SRF in targetlist handling)
Date: 2016-09-02 16:08:02
Message-ID: CACjxUsM=EqOQh3GEzu2+OrBgVUFcsDdEkNLGgviioehpA0nQbQ@mail.gmail.com
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On Fri, Sep 2, 2016 at 10:10 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Kevin Grittner <kgrittn(at)gmail(dot)com> writes:
>> On Fri, Sep 2, 2016 at 9:51 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> regression=# select *, generate_series(1,3) from int8_tbl;
>
>> I'm sure that you realize that running a query of that form twice
>> against a table with more than one heap page could result in rows
>> in a different order, even if no changes had been made to the
>> database (including no vacuum activity, auto- or otherwise).
>
> You missed my point: they might complain about the generate_series
> output not being in the order they expect, independently of what
> the table rows are.

I didn't miss it, I just never thought that anyone would care about
a secondary sort key if the primary sort key was random. I have
trouble imagining a use-case for that.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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