[Pdns-users] SLAVE refresh performance

Peter van Dijk peter.van.dijk at netherlabs.nl
Tue Sep 13 08:29:30 UTC 2011

On Sep 13, 2011, at 7:58 AM, Klaus Darilion wrote:

> How does PowerDNS architecture work? It seems that lookups performed by
> the "ueberbackend" are cached whereas lookups which are done by the
> gsql-backend are not cached. Is this correct?

This is correct. The ueberbackend (UeberBackend::lookup) consults the querycache (UeberBackend::cacheHas) before consulting the actual backends. When an actual backend needs information for itself (like, in this situation, for checking SOAs to determine freshness) it does not talk to the PDNS query cache. These backends may of course benefit from caching in the actual SQL-server.

Kind regards,
Peter van Dijk

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