| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Peter Eisentraut <peter_e(at)gmx(dot)net> |
| Cc: | Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Joachim Wieland <joe(at)mcknight(dot)de>, Noah Misch <noah(at)leadboat(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Snapshot synchronization, again... |
| Date: | 2011-02-20 00:26:42 |
| Message-ID: | 643.1298161602@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Peter Eisentraut <peter_e(at)gmx(dot)net> writes:
> On fre, 2011-02-18 at 16:57 -0300, Alvaro Herrera wrote:
>> 2. is md5 the most appropriate digest for this? If you need a
>> cryptographically secure hash, do we need something stronger? If not,
>> why not just use hash_any?
> MD5 is probably more appropriate than hash_any, because the latter is
> optimized for speed and collision avoidance and doesn't have a
> guaranteed external format. The only consideration against MD5 might be
> that it would make us look quite lame.
Only to people who don't understand whether crypto strength is actually
important in a given use-case.
However ... IIRC, hash_any gives different results on bigendian and
littleendian machines. I'm not sure if a predictable cross-platform
result is important for this use? If you're hashing data containing
native integers, this is a problem anyway.
regards, tom lane
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