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This module contains classes that are required by a task manager for
execution of table programs. The content of this module is work-in-progress.
It will replace the runtime classes contained in flink-table-planner once
it is stable. See FLINK-11439 and FLIP-32 for more details.
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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* 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
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.flink.table.runtime.functions.scalar;
import org.apache.flink.annotation.Internal;
import org.apache.flink.table.api.TableException;
import org.apache.flink.table.connector.source.abilities.SupportsSourceWatermark;
import org.apache.flink.table.data.TimestampData;
import org.apache.flink.table.functions.BuiltInFunctionDefinitions;
import org.apache.flink.table.functions.SpecializedFunction.SpecializedContext;
import javax.annotation.Nullable;
/** Implementation of {@link BuiltInFunctionDefinitions#SOURCE_WATERMARK}. */
@Internal
public class SourceWatermarkFunction extends BuiltInScalarFunction {
public static final String ERROR_MESSAGE =
String.format(
"SOURCE_WATERMARK() is a declarative marker function and doesn't have concrete "
+ "runtime implementation. It can only be used as a single expression in a "
+ "WATERMARK FOR clause in the CREATE TABLE DDL. The declaration will be "
+ "pushed down into a table source that implements the '%s' interface. "
+ "The source will emit system-defined watermarks afterwards. Please "
+ "check the documentation whether the connector supports source watermarks.",
SupportsSourceWatermark.class.getName());
private static final long serialVersionUID = 1L;
public SourceWatermarkFunction(SpecializedContext context) {
super(BuiltInFunctionDefinitions.SOURCE_WATERMARK, context);
}
public @Nullable TimestampData eval() {
throw new TableException(ERROR_MESSAGE);
}
}