Controller
The Pinot Controller is responsible for the following:
Maintaining global metadata (e.g. configs and schemas) of the system with the help of Zookeeper which is used as the persistent metadata store.
Hosting the Helix Controller and managing other Pinot components (brokers, servers, minions)
Maintaining the mapping of which servers are responsible for which segments. This mapping is used by the servers to download the portion of the segments that they are responsible for. This mapping is also used by the broker to decide which servers to route the queries to.
Serving admin endpoints for viewing, creating, updating, and deleting configs, which are used to manage and operate the cluster.
Serving endpoints for segment uploads, which are used in offline data pushes. They are responsible for initializing real-time consumption and coordination of persisting real-time segments into the segment store periodically.
Undertaking other management activities such as managing retention of segments, validations.
For redundancy, there can be multiple instances of Pinot controllers. Pinot expects that all controllers are configured with the same back-end storage system so that they have a common view of the segments (e.g. NFS). Pinot can use other storage systems such as HDFS or ADLS.
Controller periodic tasks
The Controller runs several periodic tasks in the background, to perform activities such as management and validation. Each periodic task has its own configs to define the run frequency and default frequency. Each task runs at its own schedule or can also be triggered manually if needed. The task runs on the lead controller for each table.
Here's a list of all the periodic tasks
BrokerResourceValidationManager
This task rebuilds the BrokerResource if the instance set has changed.
| Config | Default Value |
|---|---|
controller.broker.resource.validation.frequencyPeriod | 1h |
controller.broker.resource.validation.initialDelayInSeconds | between 2m-5m |
MinionInstancesCleanupTask
TBD
OfflineSegmentIntervalChecker
This task manages the segment ValidationMetrics (missingSegmentCount, offlineSegmentDelayHours, lastPushTimeDelayHours, TotalDocumentCount, NonConsumingPartitionCount, SegmentCount), to ensure that all offline segments are contiguous (no missing segments) and that the offline push delay isn't too high.
| Config | Default Value |
|---|---|
controller.offline.segment.interval.checker.frequencyPeriod | 24h |
controller.statuschecker.waitForPushTimePeriod | 10m |
controller.offlineSegmentIntervalChecker.initialDelayInSeconds | between 2m-5m |
PinotTaskManager
TBD
RealtimeSegmentValidationManager
This task validates the ideal state and segment zk metadata of realtime tables,
fixing any partitions which have stopped consuming
starting consumption from new partitions
uploading segments to deep store if segment download url is missing
This task ensures that the consumption of the realtime tables gets fixed and keeps going when met with erroneous conditions.
This task does not fix consumption stalled due to
CONSUMING segment being deleted
Kafka OOR exceptions
| Config | Default Value |
|---|---|
controller.realtime.segment.validation.frequencyPeriod | 1h |
controller.realtime.segment.validation.initialDelayInSeconds | between 2m-5m |
RetentionManager
This task manages retention of segments for all tables. During the run, it looks at the retentionTimeUnit and retentionTimeValue inside the segmentsConfig of every table, and deletes segments which are older than the retention. The deleted segments are moved to a DeletedSegments folder colocated with the dataDir on segment store, and permanently deleted from that folder in a configurable number of days.
| Config | Default Value |
|---|---|
controller.retention.frequencyPeriod | 6h |
controller.retentionManager.initialDelayInSeconds | between 2m-5m |
controller.deleted.segments.retentionInDays | 7d |
SegmentRelocator
This task is applicable only if you have tierConfig or tagOverrideConfig. It runs rebalance in the background to
relocate COMPLETED segments to tag overrides
relocate ONLINE segments to tiers if tier configs are set
At most one replica is allowed to be unavailable during rebalance.
| Config | Default Value |
|---|---|
controller.segment.relocator.frequencyPeriod | 1h |
controller.segmentRelocator.initialDelayInSeconds | between 2m-5m |
SegmentStatusChecker
This task manages segment status metrics such as realtimeTableCount, offlineTableCount, disableTableCount, numberOfReplicas, percentOfReplicas, percentOfSegments, idealStateZnodeSize, idealStateZnodeByteSize, segmentCount, segmentsInErrorState, tableCompressedSize.
| Config | Default Value |
|---|---|
controller.statuschecker.frequencyPeriod | 5m |
controller.statusChecker.initialDelayInSeconds | between 2m-5m |
TaskMetricsEmitter
TBD
Running the periodic task manually
Use the GET /periodictask/names API to fetch the names of all the Periodic Tasks running on your Pinot cluster.
To manually run a named Periodic Task use the GET /periodictask/run API
The Log Request Id (api-09630c07) can be used to search through pinot-controller log file to see log entries related to execution of the Periodic task that was manually run.
If tableName (and its type OFFLINE or REALTIME) is not provided, the task will run against all tables.
Starting a Controller
Make sure you've setup Zookeeper. If you're using docker, make sure to pull the pinot docker image. To start a controller
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