[GitHub] [ignite] rkondakov commented on a change in pull request #7909: IGNITE-13021: Calcite integration. Avoid full scans for disjunctive queries.

[GitBox <gi...@apache.org>]

rkondakov commented on a change in pull request #7909:
URL: https://github.com/apache/ignite/pull/7909#discussion_r437289158



##########
File path: modules/calcite/src/main/java/org/apache/ignite/internal/processors/query/calcite/rule/logical/LogicalOrToUnionRule.java
##########
@@ -0,0 +1,93 @@
+/*
+ * 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.ignite.internal.processors.query.calcite.rule.logical;
+
+import com.google.common.collect.ImmutableMap;
+import java.util.List;
+import org.apache.calcite.plan.RelOptCluster;
+import org.apache.calcite.plan.RelOptRule;
+import org.apache.calcite.plan.RelOptRuleCall;
+import org.apache.calcite.plan.RelOptUtil;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.core.RelFactories;
+import org.apache.calcite.rel.logical.LogicalFilter;
+import org.apache.calcite.rex.RexNode;
+import org.apache.calcite.rex.RexUtil;
+import org.apache.calcite.sql.SqlKind;
+import org.apache.calcite.tools.RelBuilder;
+
+/**
+ * Converts OR to UNION ALL.
+ */
+public class LogicalOrToUnionRule extends RelOptRule {
+    /** Instance. */
+    public static final RelOptRule INSTANCE = new LogicalOrToUnionRule(LogicalFilter.class, "LogicalOrToUnionRule");
+
+    /**
+     * Constructor.
+     *
+     * @param clazz Class of relational expression to match.
+     * @param desc  Description, or null to guess description
+     */
+    private LogicalOrToUnionRule(Class<LogicalFilter> clazz, String desc) {
+        super(
+            operand(clazz, any()),
+            RelFactories.LOGICAL_BUILDER, desc);
+    }
+
+    /** {@inheritDoc} */
+    @Override public void onMatch(RelOptRuleCall call) {
+        final LogicalFilter rel = call.rel(0);
+        final RelOptCluster cluster = rel.getCluster();
+
+        RexNode dnf = RexUtil.toDnf(cluster.getRexBuilder(), rel.getCondition());
+
+        if (!dnf.isA(SqlKind.OR))
+            return;
+
+        List<RexNode> operands = RelOptUtil.disjunctions(dnf);
+
+        if (operands.size() != 2)
+            return;
+
+        RelNode input = rel.getInput(0);
+
+        call.transformTo(rel, ImmutableMap.of(
+            createUnionAll(cluster, input, operands.get(0), operands.get(1)), rel,
+            createUnionAll(cluster, input, operands.get(1), operands.get(0)), rel
+        ));
+    }
+
+    /**
+     * Creates 'UnionAll' for conditions.
+     *
+     * @param cluster The cluster UnionAll expression will belongs to.
+     * @param input Input.
+     * @param op1 First filter condition.
+     * @param op2 Second filter condition.
+     * @return UnionAll expression.
+     */
+    private RelNode createUnionAll(RelOptCluster cluster, RelNode input, RexNode op1, RexNode op2) {
+        RelBuilder builder = relBuilderFactory.create(cluster, null);
+
+        builder.push(input).filter(op1);
+        builder.push(input).filter(RexUtil.andNot(cluster.getRexBuilder(), op2, op1));

Review comment:
       How `RexUtil.andNot` handles `NULL` value? In the ticket's example
   ```
   SELECT * FROM emps WHERE name='A' 
   UNION ALL
   SELECT * FROM emps WHERE surname='B'  AND LNNVL(name='A')
   ```
   we need to make sure that row `name=NULL, surname=B` will be returned by the rewritten plan. Can we verify it by writing a test?




----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

For queries about this service, please contact Infrastructure at:
users@infra.apache.org