Re: To know what a macro does

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Werner Echezuria <wercool(at)gmail(dot)com>
Cc: Martijn van Oosterhout <kleptog(at)svana(dot)org>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: To know what a macro does
Date: 2009-04-27 14:24:39
Message-ID: 20104.1240842279@sss.pgh.pa.us
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Werner Echezuria <wercool(at)gmail(dot)com> writes:
> Later in planner.c on grouping_planner function I do something like this:

Well, you've omitted showing us the code where the problem is likely to
be, but I am kinda thinking that you've shot yourself in the foot by
trying to represent your special ordering clause as a simple constant.
The planner is quite smart enough to throw away "order by constant"
as a no-op. By the time you get down to the pathkey logic it's just
going to be ignoring that clause entirely; and if you try to brute-force
it you're more than likely going to break something.

Rather than kluging up any of this code, I wonder whether you couldn't
represent your fuzzy sorting requirement as ORDER BY some_function(...)
and put all the smarts into that function.

regards, tom lane

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