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Re: Sorting Tuples

From: Manolo <manolo(dot)espa(at)gmail(dot)com>
To: Kenneth Marshall <ktm(at)rice(dot)edu>
Cc: pgsql-novice(at)postgresql(dot)org
Subject: Re: Sorting Tuples
Date: 2008-03-13 13:32:12
Message-ID: 1205415132.7680.8.camel@localhost.localdomain (view raw or flat)
Thread:
Lists: pgsql-novice

Good job... even if it requires 10GB more of disk space (5GB for the
unpatched and 5GB for the patched result) and multiplying by 3 or 4 the
time needed to scan a 5GB table (twice for producing the sorted result
and once or twice in order to produce the diff).

Till now it's the candidate method: I could run it ad night while I'm
sleeping!

Thank you Ken!


On Thu, 2008-03-13 at 07:32 -0500, Kenneth Marshall wrote:
> Run the same query on an un-patched version and diff the output.
> 
> Ken
> 
> On Thu, Mar 13, 2008 at 12:25:53PM +0100, Manolo wrote:
> > Hi to all.
> > 
> > INTRODUCTION:
> > I created a patch for PostgreSQL even if i'm not a PostgreSQL user. I
> > just wanted to implement an idea for possibly getting better External
> > Sorting module on PostgreSQL just using some basic C programming
> > knowledge and now I'm facing to using PostgreSQL for a while in order to
> > test my patch.
> > My patch "activates" when user is trying to sort a load of data more or
> > less twice bigger than his available memory (e.g.: sorting 5GB of data
> > just disposing of 1GB of available memory)
> > 
> > PROBLEM:
> > First of all I want to realise my patch does sorts correctly or not. But
> > it's a little bit difficult to check when
> > 
> > 	SELECT * FROM huge_table ORDER BY a_column_of_huge_table;
> > 
> > means checking a 4 or 5 GB result...
> > 
> > QUESTION:
> > Is there a way to discover if data is sorted correctly other than
> > spending 2 months taking a look to the 5 GB result tuples, one by one?
> > 
> > Thanks for your attention.
> > Regards, Manolo.
> > 
> > 
> > -- 
> > Sent via pgsql-novice mailing list (pgsql-novice(at)postgresql(dot)org)
> > To make changes to your subscription:
> > http://www.postgresql.org/mailpref/pgsql-novice
> > 


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