auth: Do an ANY lookup for all types then filter

docs/settings.rst

@@ -307,6 +307,22 @@ compile-time.
 Name of this virtual configuration - will rename the binary image. See
 :doc:`guides/virtual-instances`.
 
+.. _setting-consistent-backends:
+
+``consistent-backends``
+--------------------
+
+-  Boolean
+-  Default: no
+
+.. versionadded:: 4.4.0
+
+When this is set, PowerDNS assumes that any single domain lives in only one backend.
+This allows PowerDNS to send ANY lookups to its backends, instead of sometimes requesting the exact needed type.
+This reduces the load on backends by retrieving all the types for a given name at once, adding all of them to the cache.
+It improves performance significantly for latency-sensitive backends, like SQL ones, where a round-trip takes serious time.
+This behaviour will be enabled by default in a future release.
+
 .. _setting-control-console:
 
 ``control-console``

pdns/common_startup.cc

@@ -245,6 +245,8 @@ void declareArguments()
 
   ::arg().set("max-generate-steps", "Maximum number of $GENERATE steps when loading a zone from a file")="0";
 
+  ::arg().set("consistent-backends", "Assume individual domains are not divided over backends. Send only ANY lookup operations to the backend to reduce the number of lookups")="yes";
+
   ::arg().set("rng", "Specify the random number generator to use. Valid values are auto,sodium,openssl,getrandom,arc4random,urandom.")="auto";
   ::arg().setDefaults();
 }

pdns/dnsbackend.cc

@@ -32,6 +32,9 @@
 #include "pdns/packetcache.hh"
 #include "dnspacket.hh"
 #include "dns.hh"
+#include "statbag.hh"
+
+extern StatBag S;
 
 // this has to be somewhere central, and not in a file that requires Lua
 // this is so the geoipbackend can set this pointer if loaded for lua-record.cc
@@ -241,6 +244,7 @@ vector<DNSBackend *> BackendMakerClass::all(bool metadataOnly)
 bool DNSBackend::getSOA(const DNSName &domain, SOAData &sd)
 {
   this->lookup(QType(QType::SOA),domain,-1);
+  S.inc("backend-queries");
 
   DNSResourceRecord rr;
   rr.auth = true;

pdns/pdnsutil.cc

@@ -135,6 +135,7 @@ static void loadMainConfig(const std::string& configdir)
   ::arg().set("chroot","Switch to this chroot jail")="";
   ::arg().set("dnssec-key-cache-ttl","Seconds to cache DNSSEC keys from the database")="30";
   ::arg().set("domain-metadata-cache-ttl","Seconds to cache domain metadata from the database")="60";
+  ::arg().set("consistent-backends", "Assume individual domains are not divided over backends. Send only ANY lookup operations to the backend to reduce the number of lookups")="yes";
 
   // Keep this line below all ::arg().set() statements
   if (! ::arg().laxFile(configname.c_str()))

pdns/test-ueberbackend_cc.cc

@@ -335,6 +335,7 @@ struct UeberBackendSetupArgFixture {
     extern AuthQueryCache QC;
     ::arg().set("query-cache-ttl")="0";
     ::arg().set("negquery-cache-ttl")="0";
+    ::arg().set("consistent-backends")="no";
     QC.cleanup();
     BackendMakers().clear();
     SimpleBackend::s_zones.clear();