[Pdns-users] Two questions about powerdns

Derrik Pates demon at devrandom.net
Sun Jan 29 14:00:30 UTC 2006

Norbert Sendetzky wrote:
> I've implemented something similar in the opendbx backend. Similar because the  
> patch that was attached to your mail has some major performance implications. 

How so? For the gsql backend, the whole idea is for it to generate
*fewer* queries, not more. It only generates one additional query to get
the zone serial, the 'select max(change_date) from records where
domain_id=%d' query. Assuming that works, it skips the (old, bad) way of
dumping every record for the zone. I could probably remove that stuff
anyway, since for some reason, it doesn't actually work.

> The implementation in the opendbx backend (patch sent to pdns-dev) uses the 
> change_date field in the SOA row if the serial field in the SOA record is set 
> to 0. This simplifies the task for the backend very much and doesn't cost any 
> additional resources. It also simplifies the management issue because the 
> tools don't have to parse and change the SOA records. The only annoyance is 
> that the management tools must set the change_date field of the SOA row if a 
> record in the zone is changed, which requires two queries instead of one.
> Is this a feasable way to solve the problem?

Not really, since at that point you may as well just explode the SOA and
update the serial, it's not significantly more work. The whole *point*
of my patch is to reduce the scan-all stuff into a single query (which
on a sanely-indexed tablespace will be pretty cheap) as opposed to the
scan-all-records-in-zone method.


Derrik Pates
demon at devrandom.net

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