| From: | Jeff Davis <pgsql(at)j-davis(dot)com> |
|---|---|
| To: | Hannu Krosing <hannu(at)2ndQuadrant(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Asko Oja <ascoja(at)gmail(dot)com>, Kenneth Marshall <ktm(at)rice(dot)edu>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: [PATCHES] updated hash functions for postgresql v1 |
| Date: | 2009-10-28 19:51:49 |
| Message-ID: | 1256759509.10769.105.camel@monkey-cat.sm.truviso.com |
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| Lists: | pgsql-hackers |
On Wed, 2009-10-28 at 21:09 +0200, Hannu Krosing wrote:
> Is at least the fact that they "are undocumented, have changed in the
> past, and are likely to change again in the future" documented ?
That's a little confusing to me: how do we document that something is
undocumented? And where do we stop?
> Hashing is a quite fundamental thing in computing, so I was quite
> surprised to find out it had silently changed.
There are many reasons to use a hash, and we don't want people to use
these functions for the wrong purpose. I have seen people use a
performance hash for security purposes before, and I had to demonstrate
some hash collisions to show why that was a bad idea. So, if we do
provide documented functions, it should be done carefully.
Trying to develop and document a set of standardized, stable hash
functions covering a wide range of possible use cases sounds like it may
be better served by an extension.
Regards,
Jeff Davis
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