Re: Switching exim4 to libdb4.2
On 2004-07-11 Steve Langasek <vorlon@debian.org> wrote:
> On Sat, Jul 10, 2004 at 09:11:57AM +0200, Andreas Metzler wrote:
>> Due to a wishlist bugreport (#258311) we are considering to switch
>> exim4 to a newer version of BerkelyDB, namely libdb4.2. As we are
>> pre-release I am asking you whether this would be acceptable before
>> spending any further thought on it.
>> Afaict it will not mess up d-i/debootstrap because libdb4.2 is already
>> listed in base as dependency of apt-utils. (Perhaps libdb3 can be
>> removed, but I am not 100% sure.)
> How much testing have you done to ensure that switching db libs won't
> break users' ability to use existing db3 databases?
Hello,
Not much yet because I wanted to know whether this might be acceptable
for sarge *before* I invested lots of (perhaps useless) effort in it.
I've built exim against db(2|3|4.(0|1|2)), generated small bdbs with
the accompaning version of exim_dbmbuild and checked how "exim4 -be
'${lookup {string} dbm {db}}'" behaved. The results were encouraging,
this kind of ro-access generally seems to be backwards compatible:
\ can read db generated with exim_dbmbuild
eximbinary | 2 | 3 | 4.0 | 4.1 | 4.2
-----------+-----+-----+-----+-----+-----
2 | y | n | n | n | n
3 | n | y | y | n | n
4.0 | n | y | y | n | n
4.1 | n | y | y | y | y
4.2 | n | y | y | y | y
db2 was never used for exim, I only added it to the test because I
know that there were upgrading problems, i.e. old bds that could not
be read by newer exim and wanted to reproduce them.
I have not tested rw access (i.e. running for example exim+db4.2 with
a /var/spool/exim/db that contained hints-databases generated by
exim+db3) but I do not intend to, I'll probabably be simply
overcautious and will just zap the hints databases on the upgrade.
Testing against dbs generated by something else but exim_dbmbuild is
completely missing and actually I have not thought about it yet
(suggestions are welcome).
cu andreas
--
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fuhggvat qbja gur juveyvat tha.
Neal Stephenson in "Snow Crash"
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