org.apache.flink.table.sources.TableSource Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
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package org.apache.flink.table.sources;
import org.apache.flink.annotation.PublicEvolving;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.table.api.DataTypes;
import org.apache.flink.table.api.TableException;
import org.apache.flink.table.api.TableSchema;
import org.apache.flink.table.connector.source.DynamicTableSource;
import org.apache.flink.table.types.DataType;
import org.apache.flink.table.utils.TableConnectorUtils;
import static org.apache.flink.table.types.utils.TypeConversions.fromLegacyInfoToDataType;
/**
* Defines an external table with the schema that is provided by {@link TableSource#getTableSchema}.
*
* The data of a {@link TableSource} is produced as a {@code DataStream} in case of a {@code
* StreamTableSource}. The type of this produced {@code DataStream} is specified by the {@link
* TableSource#getProducedDataType()} method.
*
*
By default, the fields of the {@link TableSchema} are implicitly mapped by name to the fields
* of the produced {@link DataType}. An explicit mapping can be defined by implementing the {@link
* DefinedFieldMapping} interface.
*
* @param The return type of the {@link TableSource}.
* @deprecated This interface has been replaced by {@link DynamicTableSource}. The new interface
* produces internal data structures. See FLIP-95 for more information.
*/
@Deprecated
@PublicEvolving
public interface TableSource {
/**
* Returns the {@link DataType} for the produced data of the {@link TableSource}.
*
* @return The data type of the returned {@code DataStream}.
*/
default DataType getProducedDataType() {
final TypeInformation legacyType = getReturnType();
if (legacyType == null) {
throw new TableException("Table source does not implement a produced data type.");
}
return fromLegacyInfoToDataType(legacyType).notNull();
}
/**
* @deprecated This method will be removed in future versions as it uses the old type system. It
* is recommended to use {@link #getProducedDataType()} instead which uses the new type
* system based on {@link DataTypes}. Please make sure to use either the old or the new type
* system consistently to avoid unintended behavior. See the website documentation for more
* information.
*/
@Deprecated
default TypeInformation getReturnType() {
return null;
}
/**
* Returns the schema of the produced table.
*
* @return The {@link TableSchema} of the produced table.
* @deprecated Table schema is a logical description of a table and should not be part of the
* physical TableSource. Define schema when registering a Table either in DDL or in {@code
* TableEnvironment#connect(...)}.
*/
@Deprecated
TableSchema getTableSchema();
/**
* Describes the table source.
*
* @return A String explaining the {@link TableSource}.
*/
default String explainSource() {
return TableConnectorUtils.generateRuntimeName(
getClass(), getTableSchema().getFieldNames());
}
}