org.apache.flink.table.sources

Interface ProjectableTableSource<T>

Type Parameters:

T - The return type of the TableSource.

@PublicEvolving
public interface ProjectableTableSource<T>

Adds support for projection push-down to a TableSource.

A TableSource extending this interface is able to project the fields of the returned DataSet if it is a BatchTableSource or DataStream if it is a StreamTableSource.

Method Summary

Modifier and Type	Method and Description
TableSource<T>	projectFields(int[] fields) Creates a copy of the TableSource that projects its output to the given field indexes.

Method Detail

projectFields

TableSource<T> projectFields(int[] fields)

Creates a copy of the TableSource that projects its output to the given field indexes. The field indexes relate to the physical poduced data type (TableSource.getProducedDataType()) and not to the table schema (TableSource.getTableSchema() of the TableSource.

The table schema (TableSource.getTableSchema() of the TableSource copy must not be modified by this method, but only the produced data type (TableSource.getProducedDataType()) and the produced DataSet (BatchTableSource#getDataSet() or DataStream (StreamTableSource#getDataStream).

If the TableSource implements the DefinedFieldMapping interface, it might be necessary to adjust the mapping as well.

IMPORTANT: This method must return a true copy and must not modify the original table source object.

Parameters:

fields - The indexes of the fields to return.

Returns:

A copy of the TableSource that projects its output.