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commit a2e7416e132e3f980c844f3fe4007a4ad306e324 Author: godfreyhe <[email protected]> AuthorDate: Sun Jun 12 16:22:18 2022 +0800 [FLINK-27983][table-common] Introduce SupportsStatisticsReport interface This closes #19939 --- .../source/abilities/SupportsStatisticReport.java | 47 ++++++++++++++++++++++ 1 file changed, 47 insertions(+) diff --git a/flink-table/flink-table-common/src/main/java/org/apache/flink/table/connector/source/abilities/SupportsStatisticReport.java b/flink-table/flink-table-common/src/main/java/org/apache/flink/table/connector/source/abilities/SupportsStatisticReport.java new file mode 100644 index 00000000000..08a80035eaa --- /dev/null +++ b/flink-table/flink-table-common/src/main/java/org/apache/flink/table/connector/source/abilities/SupportsStatisticReport.java @@ -0,0 +1,47 @@ +/* + * 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.connector.source.abilities; + +import org.apache.flink.annotation.PublicEvolving; +import org.apache.flink.table.connector.source.DynamicTableSource; +import org.apache.flink.table.plan.stats.TableStats; + +/** + * Enables to report the estimated statistics provided by the {@link DynamicTableSource}. + * + * <p>Statistics are one of the most important inputs to the optimizer cost model, which will + * generate the most effective execution plan with the lowest cost among all considered candidate + * plans. + * + * <p>This interface is used to compensate for the missing of statistics in the catalog. The planner + * will call {@link #reportStatistics} method when the planner detects the statistics from catalog + * is unknown. Therefore, the method will be executed as needed. + * + * <p>Note: This method is called at plan optimization phase, the implementation of this interface + * should be as light as possible, but more complete information. + */ +@PublicEvolving +public interface SupportsStatisticReport { + + /** + * Returns the estimated statistics of this {@link DynamicTableSource}, else {@link + * TableStats#UNKNOWN} if some situations are not supported or cannot be handled. + */ + TableStats reportStatistics(); +}
