Connectors

Instances of your connector splits.

The method indicates the node affinity of a Split,it has three options:

HARD_AFFINITY: Split is NOT remotely accessible and has to be on specific nodes

SOFT_AFFINITY: Connector split provides a list of preferred nodes for engine to pick from but not mandatory.

The method provides a list of preferred nodes for scheduler to pick.

The scheduler will respect the preference if the strategy is HARD_AFFINITY. Otherwise, the scheduler will prioritize the provided nodes if the strategy is SOFT_AFFINITY. But there is no guarantee that the scheduler will pick them if the provided nodes are busy. Empty list indicates no preference.

ConnectorFactory

Instances of your connector are created by a ConnectorFactory instance which is created when Presto calls getConnectorFactory() on the plugin. The connector factory is a simple interface responsible for creating an instance of a Connector object that returns instances of the following services:

• ConnectorHandleResolver

The connector metadata interface has a large number of important methods that are responsible for allowing Presto to look at lists of schemas, lists of tables, lists of columns, and other metadata about a particular data source.

This interface is too big to list in this documentation, but if you are interested in seeing strategies for implementing these methods, look at the and the Cassandra connector. If your underlying data source supports schemas, tables and columns, this interface should be straightforward to implement. If you are attempting to adapt something that is not a relational database (as the Example HTTP connector does), you may need to get creative about how you map your data source to Presto’s schema, table, and column concepts.

Given a split and a list of columns, the record set provider is responsible for delivering data to the Presto execution engine. It creates a , which in turn creates a RecordCursor that is used by Presto to read the column values for each row.