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Re: adding operators

From: "Islam Hegazy" <islheg(at)gmail(dot)com>
To: "Brendan Jurd" <direvus(at)gmail(dot)com>,<darcy(at)druid(dot)net>
Cc: <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: adding operators
Date: 2007-10-01 17:17:47
Message-ID: 010301c80450$cdbe6180$0d0e9f88@pc.cpsc.ucalgary.ca (view raw or flat)
Thread:
Lists: pgsql-hackers
Thanks for this information. It was really helpful.

Another problem that is facing me is altering existing functions. For 
example, what if I want to change the execution of the SUM function to work 
as follows:

select sum(a)
from mytable w(5);

which means to sum only 5 records or records that arrived in the last 5 
minutes. Do I need to change the core code of PostgreSQL to implement such 
thing?

Regards
Islam Hegazy



----- Original Message ----- 
From: "Brendan Jurd" <direvus(at)gmail(dot)com>
To: "Islam Hegazy" <islheg(at)gmail(dot)com>
Cc: <pgsql-hackers(at)postgresql(dot)org>
Sent: Sunday, September 30, 2007 8:38 PM
Subject: Re: [HACKERS] adding operators


> On 10/1/07, Islam Hegazy <islheg(at)gmail(dot)com> wrote:
>> I am a graduate student in the University of Calgary. I want to add some 
>> new
>> operators to PostgreSQL to perform some specific tasks in a project I am
>> working in. My problem is that I cannot find my way into the code, where
>> should I start and where to find the documentation for the code.
>
> There's no need to hack Postgres to add operators.  You can do so by
> defining functions using CREATE FUNCTION, and then hooking operators
> up to them using CREATE OPERATOR.
>
> http://www.postgresql.org/docs/8.2/static/xoper.html
> http://www.postgresql.org/docs/8.2/static/sql-createoperator.html
>
> Regards,
> BJ 


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