Package org.apache.pinot.broker.routing.instanceselector

Class MultiStageReplicaGroupSelector

  • All Implemented Interfaces:
    InstanceSelector
    public class MultiStageReplicaGroupSelector
extends Object
    Instance selector for multi-stage queries which can ensure that Colocated Tables always leverage Colocated Join whenever possible. To achieve this, this instance-selector uses InstancePartitions (IP) to determine replica-groups, as opposed to IdealState used by other instance-selectors. Moreover, this also uses the requestId generated by Pinot broker to determine the replica-group picked for each table involved in the query, as opposed to using a member variable. There may be scenarios where an instance in the chosen replica-group is down. In that case, this strategy will try to pick another replica-group. For realtime tables, this strategy uses only CONSUMING partitions. This is feature is in Beta.

    • Constructor Detail

      • MultiStageReplicaGroupSelector

        public MultiStageReplicaGroupSelector​(String tableNameWithType,
                                      org.apache.helix.store.zk.ZkHelixPropertyStore<org.apache.helix.zookeeper.datamodel.ZNRecord> propertyStore,
                                      org.apache.pinot.common.metrics.BrokerMetrics brokerMetrics,
                                      @Nullable
                                      AdaptiveServerSelector adaptiveServerSelector,
                                      Clock clock)

    • Method Detail

      • init

        public void init​(Set<String> enabledInstances,
                 org.apache.helix.model.IdealState idealState,
                 org.apache.helix.model.ExternalView externalView,
                 Set<String> onlineSegments)
        Description copied from interface: InstanceSelector
        Initializes the instance selector with the enabled instances, ideal state, external view and online segments (segments with ONLINE/CONSUMING instances in the ideal state and pre-selected by the SegmentPreSelector). Should be called only once before calling other methods.
        Specified by:
        init in interface InstanceSelector

      • onInstancesChange

        public void onInstancesChange​(Set<String> enabledInstances,
                              List<String> changedInstances)
        Processes the instances change. Changed instances are pre-computed based on the current and previous enabled instances only once on the caller side and passed to all the instance selectors.

        Updates the cached enabled instances and re-calculates segmentToEnabledInstancesMap and unavailableSegments based on the cached states.

        Specified by:
        onInstancesChange in interface InstanceSelector

      • onAssignmentChange

        public void onAssignmentChange​(org.apache.helix.model.IdealState idealState,
                               org.apache.helix.model.ExternalView externalView,
                               Set<String> onlineSegments)
        Processes the segment assignment (ideal state or external view) change based on the given online segments (segments with ONLINE/CONSUMING instances in the ideal state and pre-selected by the SegmentPreSelector).

        Updates the cached maps (segmentToOnlineInstancesMap, segmentToOfflineInstancesMap and instanceToSegmentsMap) and re-calculates segmentToEnabledInstancesMap and unavailableSegments based on the cached states.

        Specified by:
        onAssignmentChange in interface InstanceSelector

      • getInstancePartitions

        protected org.apache.pinot.common.assignment.InstancePartitions getInstancePartitions()

      • select

        public InstanceSelector.SelectionResult select​(org.apache.pinot.common.request.BrokerRequest brokerRequest,
                                               List<String> segments,
                                               long requestId)
        Description copied from interface: InstanceSelector
        Selects the server instances for the given segments queried by the given broker request, returns a map from segment to selected server instance hosting the segment and a set of unavailable segments (no enabled instance or all enabled instances are in ERROR state).
        Specified by:
        select in interface InstanceSelector
        Parameters:
        brokerRequest - BrokerRequest for the query
        segments - segments for which instance needs to be selected
        requestId - requestId generated by the Broker for a query
        Returns:
        instance of SelectionResult which describes the instance to pick for a given segment