| From: | Craig Ringer <craig(at)2ndquadrant(dot)com> |
|---|---|
| To: | Stephen Frost <sfrost(at)snowman(dot)net> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Marko Kreen <markokr(at)gmail(dot)com>, Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: MD5 aggregate |
| Date: | 2013-06-15 03:55:56 |
| Message-ID: | 51BBE5CC.1000104@2ndquadrant.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
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On 06/14/2013 09:40 PM, Stephen Frost wrote:
> Where I'd take this is actually in a completely different direction..
> I'd like the aggregate to be able to match the results of running the
> 'md5sum' unix utility on a file that's been COPY'd out.
Until I started looking at the follow-up discussion I didn't realise it
wasn't supposed to.
If it isn't the md5sum of the ordered rows, it shouldn't be called
'md5'. It might still be useful, but please don't call it md5.
The proposals to make it produce the same result with different row
orderings sound useful in the context of SQL; if it produced a different
result with different orderings I'd want a way to force an explicit
ORDER BY clause on the aggregate and error out if one wasn't present.
Making it ignore order means that it's no longer md5, though.
row_sums(...) ?
- --
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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