Flownode

Introduction

Flownode provides a simple streaming process (known as flow) ability to the database. Flownode manages flows which are tasks that receive data from the source and send data to the sink.

Flownode support both standalone and distributed mode. In standalone mode, Flownode runs in the same process as the database. In distributed mode, Flownode runs in a separate process and communicates with the database through the network.

There are two execution modes for a flow:

• Streaming Mode: The original mode where data is processed as it arrives.
• Batching Mode: A newer mode designed for continuous data aggregation. It periodically executes a user-defined SQL query over small, discrete time windows. All aggregation queries now use this mode. For more details, see the Batching Mode Developer Guide.

Components

A Flownode contains all the components needed to execute a flow. The specific components involved depend on the execution mode (Streaming vs. Batching). At a high level, the key parts are:

• Flow Manager: A central component responsible for managing the lifecycle of all flows.
• Task Executor: The runtime environment where the flow logic is executed. In streaming mode, this is typically a FlowWorker; in batching mode, it's a BatchingTask.
• Flow Task: Represents a single, independent data flow, containing the logic for transforming data from a source to a sink.