The plumber handles generated segments both while they are being generated and when they are "done". This is also technically a pluggable interface and there are multiple implementations. However, plumbers handle numerous complex details, and therefore an advanced understanding of Druid is recommended before implementing your own.
|type|String|Specifies the type of plumber. Each value will have its own configuration schema. Plumbers packaged with Druid are described below. The default type is "realtime".|yes|
*`windowPeriod` is the amount of lag time to allow events. This is configured with a 10 minute window, meaning that any event more than 10 minutes ago will be thrown away and not included in the segment generated by the realtime server.
*`basePersistDirectory` is the directory to put things that need persistence. The plumber is responsible for the actual intermediate persists and this tells it where to store those persists.
*`maxPendingPersists` is how many persists a plumber can do concurrently without starting to block.
*`segmentGranularity` specifies the granularity of the segment, or the amount of time a segment will represent.
*`rejectionPolicy` controls how data sets the data acceptance policy for creating and handing off segments. The following policies are available:
*`serverTime`– The recommended policy for "current time" data, it is optimal for current data that is generated and ingested in real time. Uses `windowPeriod` to accept only those events that are inside the window looking forward and back.
*`messageTime`– Can be used for non-"current time" as long as that data is relatively in sequence. Events are rejected if they are less than `windowPeriod` from the event with the latest timestamp. Hand off only occurs if an event is seen after the segmentGranularity and `windowPeriod`.
*`none`– Never hands off data unless shutdown() is called on the configured firehose.
*`test`– Useful for testing that handoff is working, *not useful in terms of data integrity*. It uses the sum of `segmentGranularity` plus `windowPeriod` as a window.
