[GitHub] [flink] godfreyhe commented on a diff in pull request #22156: [FLINK-30129][table] Push projection through ChangelogNormalize

["godfreyhe (via GitHub)" <gi...@apache.org>]

godfreyhe commented on code in PR #22156:
URL: https://github.com/apache/flink/pull/22156#discussion_r1136471769


##########
flink-table/flink-table-planner/src/main/java/org/apache/flink/table/planner/plan/rules/physical/stream/PushCalcPastChangelogNormalizeRule.java:
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@@ -0,0 +1,333 @@
+/*
+ * 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.planner.plan.rules.physical.stream;
+
+import org.apache.flink.annotation.Internal;
+import org.apache.flink.table.planner.plan.nodes.physical.stream.StreamPhysicalCalc;
+import org.apache.flink.table.planner.plan.nodes.physical.stream.StreamPhysicalChangelogNormalize;
+import org.apache.flink.table.planner.plan.nodes.physical.stream.StreamPhysicalExchange;
+import org.apache.flink.table.planner.plan.trait.FlinkRelDistribution;
+
+import org.apache.calcite.plan.RelOptRule;
+import org.apache.calcite.plan.RelOptRuleCall;
+import org.apache.calcite.plan.RelOptUtil;
+import org.apache.calcite.plan.RelRule;
+import org.apache.calcite.plan.RelTraitSet;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.type.RelDataType;
+import org.apache.calcite.rex.RexInputRef;
+import org.apache.calcite.rex.RexLocalRef;
+import org.apache.calcite.rex.RexNode;
+import org.apache.calcite.rex.RexProgram;
+import org.apache.calcite.rex.RexProgramBuilder;
+import org.apache.calcite.rex.RexShuttle;
+import org.apache.calcite.rex.RexUtil;
+import org.apache.calcite.tools.RelBuilder;
+import org.apache.calcite.util.Pair;
+import org.immutables.value.Value;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+import static org.apache.flink.table.planner.plan.utils.RexNodeExtractor.extractRefInputFields;
+
+/**
+ * Pushes primary key filters and used fields project through a {@link
+ * StreamPhysicalChangelogNormalize ChangelogNormalize} operator to reduce its state size.
+ *
+ * <p>This rule looks for Calc → ChangelogNormalize where the {@link StreamPhysicalCalc Calc}
+ * contains a filter condition or a projection. The condition is transformed into CNF and then each
+ * conjunction is tested for whether it affects only primary key columns. If such conditions or
+ * projection exist, they are moved into a new, separate Calc and pushed through the
+ * ChangelogNormalize operator. ChangelogNormalize keeps state for every unique key it encounters,
+ * thus pushing filters on the primary key and projection on values in front of it helps reduce the
+ * size of its state.
+ *
+ * <p>Note that pushing primary key filters is safe to do, but pushing any other filters can lead to
+ * incorrect results.
+ */
+@Internal
+@Value.Enclosing
+public class PushCalcPastChangelogNormalizeRule

Review Comment:
   Nit: another class name can be `CalcChangelogNormalizeTransposeRule `



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