Message-ID: <439CBBC1.2030700@dunslane.net>
Date: Sun, 11 Dec 2005 18:52:33 -0500
From: Andrew Dunstan <andrew@dunslane.net>
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To: Carlos Moreno <moreno@mochima.com>
CC: pgsql-hackers@postgresql.org
Subject: Re: Please Help: PostgreSQL Query Optimizer
References: <Pine.LNX.4.61.0512111610320.4525@nsl-33.cse.iitb.ac.in>
	<200512111126.18566.josh@agliodbs.com>
	<Pine.LNX.4.61.0512120139080.6920@nsl-33.cse.iitb.ac.in>
	<439CAE4D.2030208@mochima.com>
In-Reply-To: <439CAE4D.2030208@mochima.com>
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Actually, there is probably comparatively little to gain from making it 
a builtin. And SHA1 is already there in the pgcrypto contrib module. 
Presumably if we wanted a builtin we would start from that code base.

cheers

andrew

Carlos Moreno wrote:

>
> Hi,
>
> I'm very new to this list -- I've been using and advocating PostgreSQL 
> for
> no less than 4 or 5 years now, and have participated in some of the other
> mailing lists, but never on this one.
>
> My question is (short version):  how would one go about adding a new
> (built-in) function to PostgreSQL?
>
> Long-ish version:
>
> I know the answer "in theory" -- one goes through the source code, find
> out how it all works, and modify/add the code to add or fix whatever
> feature we want.
>
> I guess my point in here would be rather a "feature request" -- except
> that I'd find it pretty exciting to implement it myself, and then propose
> the new feature by volunteering the implementation that I already wrote
> (seems like the spirit of open-source communities, right?) -- then of
> course, it would be subject to consensus, whether or not the feature
> makes sense and the implementation is good enough.
>
> I'm interested in adding additional hash functions -- PG supports, as 
> part
> of the built-in SQL functions, MD5 hashing.  So, for instance, I can 
> simply
> type, at a psql console, the following:
>
> select md5('abc');
>
> My "feature request" (which again, I'd like to implement it myself) would
> be the ability to do:
>
> select sha1('xyz'), sha256('etc');
>
> (At least these two -- maybe for completeness it would be good to have
> sha224, 384, and 512, but I guess SHA1 and SHA-256 would be a very good
> and sound starting point)
>
> So, can you offer some advice or pointers on how to go about that?
>
> I started by doing a search for the string md5 through all the source
> code -- the problem is, md5 shows up in many many many places (it is
> part of the authentication protocol, among other things), so I got a
> little bit lost searching through it all.
>
> I wonder if you have some documents specifically aimed at providing
> advice and documentation for prospective developers (or for people
> that want to "tweak" the source code to fix/tuneup or add functionality),
> I guess that would be great for me in this case.
>
>