Hi Nils, thanks for your reply.
Database transactions help in terms of integrity, but they can do nothing about
the order of data updates. If 2 threads work independently and execute the same
update query on the db, I can't predict with certainty which one will occur
first.
Fabio
Il giorno 30/dic/2011, alle ore 00:32, Nils Breunese (Lemonbit) ha scritto:
> Fabio Sangiovanni wrote:
>
>> I'm a newbie of pdns and I'm setting up a recursor-only installation as
>> local dns cache for a high load smtp server.
>> I'm using the lua scripting feature as a way to track down MX queries. In
>> particular, the preresolve() function relies on luasql to execute queries on
>> a (local) mysql database.
>> This is my problem: if I enable more than one thread in recursor.conf I get
>> the lua script loaded more than once, and ultimately concurrent queries to
>> the db that could mess up the stored data, depending on the execution order
>> of select and update queries by the various threads.
>> I'd like to avoid circumventing these race conditions through complicated
>> lua coding, and instead I'd prefer to keep things as simple as possible and
>> limit the number of pdns threads to just 1 ("threads=1" setting in
>> recursor.conf).
>> I know that the lua feature is not meant to be used this way, but this could
>> really help me solving a big problem :)
>>
>> Now my questions are:
>> am I right thinking this would solve my problem?
>> how deep is the impact on performances changing the number of threads from 2
>> (default setting) to just 1?
>> are there other sensible settings that I could adjust to better suit my
>> needs?
>
> Wouldn't using database transactions solve your integrity problem?
>
> Nils.
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