public static class DCAwareRoundRobinPolicy.Builder extends Object
Constructor and Description |
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Builder() |
Modifier and Type | Method and Description |
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DCAwareRoundRobinPolicy.Builder |
allowRemoteDCsForLocalConsistencyLevel()
Deprecated.
This functionality will be removed in the next major release of the driver. DC
failover shouldn't be done in the driver, which does not have the necessary context to
know what makes sense considering application semantics.
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DCAwareRoundRobinPolicy |
build()
Builds the policy configured by this builder.
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DCAwareRoundRobinPolicy.Builder |
withLocalDc(String localDc)
Sets the name of the datacenter that will be considered "local" by the policy.
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DCAwareRoundRobinPolicy.Builder |
withUsedHostsPerRemoteDc(int usedHostsPerRemoteDc)
Deprecated.
This functionality will be removed in the next major release of the driver. DC
failover shouldn't be done in the driver, which does not have the necessary context to
know what makes sense considering application semantics.
|
public DCAwareRoundRobinPolicy.Builder withLocalDc(String localDc)
This must be the name as known by Cassandra (in other words, the name in that appears in
system.peers
, or in the output of admin tools like nodetool).
If this method isn't called, the policy will default to the datacenter of the first node
connected to. This will always be ok if all the contact points use at Cluster
creation are in the local data-center. Otherwise, you should provide the name yourself with
this method.
localDc
- the name of the datacenter. It should not be null
.@Deprecated public DCAwareRoundRobinPolicy.Builder withUsedHostsPerRemoteDc(int usedHostsPerRemoteDc)
The policy's distance()
method will return a HostDistance.REMOTE
distance
for only usedHostsPerRemoteDc
hosts per remote datacenter. Other hosts of the remote
datacenters will be ignored (and thus no connections to them will be maintained).
If usedHostsPerRemoteDc > 0
, then if for a query no host in the local datacenter
can be reached and if the consistency level of the query is not LOCAL_ONE
or LOCAL_QUORUM
, then up to usedHostsPerRemoteDc
hosts per remote datacenter will be
tried by the policy as a fallback. By default, no remote host will be used for LOCAL_ONE
and LOCAL_QUORUM
, since this would change the meaning of the consistency
level, somewhat breaking the consistency contract (this can be overridden with allowRemoteDCsForLocalConsistencyLevel()
).
If this method isn't called, the policy will default to 0.
usedHostsPerRemoteDc
- the number.@Deprecated public DCAwareRoundRobinPolicy.Builder allowRemoteDCsForLocalConsistencyLevel()
LOCAL_ONE
or LOCAL_QUORUM
.
When used in conjunction with usedHostsPerRemoteDc
> 0, this overrides the policy of never using remote datacenter nodes for LOCAL_ONE
and LOCAL_QUORUM
queries. It is however inadvisable to do so in almost all cases, as
this would potentially break consistency guarantees and if you are fine with that, it's
probably better to use a weaker consistency like ONE
, TWO
or THREE
.
As such, this method should generally be avoided; use it only if you know and understand what
you do.
public DCAwareRoundRobinPolicy build()
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