[GitHub] [calcite] jinxing64 commented on a change in pull request #1451: [CALCITE-3334] Refinement for Substitution-Based MV Matching

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jinxing64 commented on a change in pull request #1451: [CALCITE-3334] Refinement for Substitution-Based MV Matching
URL: https://github.com/apache/calcite/pull/1451#discussion_r338362543
 
 

 ##########
 File path: core/src/main/java/org/apache/calcite/plan/SubstitutionVisitor.java
 ##########
 @@ -997,233 +1022,520 @@ public UnifyResult apply(UnifyRuleCall call) {
     }
   }
 
-  /** Implementation of {@link UnifyRule} that matches
-   * {@link org.apache.calcite.rel.core.TableScan}. */
-  private static class ScanToProjectUnifyRule extends AbstractUnifyRule {
-    public static final ScanToProjectUnifyRule INSTANCE =
-        new ScanToProjectUnifyRule();
+  /**
+   * A {@link SubstitutionVisitor.UnifyRule} that matches a
+   * {@link MutableScan} to a {@link MutableCalc} which has {@link MutableScan} as child.
+   */
+  private static class ScanToCalcUnifyRule extends AbstractUnifyRule {
+
+    public static final ScanToCalcUnifyRule INSTANCE = new ScanToCalcUnifyRule();
 
-    private ScanToProjectUnifyRule() {
-      super(any(MutableScan.class),
-          any(MutableProject.class), 0);
+    private ScanToCalcUnifyRule() {
+      super(
+          any(MutableScan.class),
+          operand(MutableCalc.class,
+              any(MutableScan.class)),
+          0);
     }
 
-    public UnifyResult apply(UnifyRuleCall call) {
-      final MutableProject target = (MutableProject) call.target;
+    @Override protected UnifyResult apply(UnifyRuleCall call) {
+
       final MutableScan query = (MutableScan) call.query;
-      // We do not need to check query's parent type to avoid duplication
-      // of ProjectToProjectUnifyRule or FilterToProjectUnifyRule, since
-      // SubstitutionVisitor performs a top-down match.
-      if (!query.equals(target.getInput())) {
-        return null;
-      }
-      final RexShuttle shuttle = getRexShuttle(target);
-      final RexBuilder rexBuilder = target.cluster.getRexBuilder();
-      final List<RexNode> newProjects;
-      try {
-        newProjects = (List<RexNode>)
-            shuttle.apply(rexBuilder.identityProjects(query.rowType));
-      } catch (MatchFailed e) {
-        return null;
-      }
-      final MutableProject newProject =
-          MutableProject.of(query.rowType, target, newProjects);
-      final MutableRel newProject2 = MutableRels.strip(newProject);
-      return call.result(newProject2);
-    }
-  }
 
-  /** Implementation of {@link UnifyRule} that matches
-   * {@link org.apache.calcite.rel.core.Project}. */
-  private static class ProjectToProjectUnifyRule extends AbstractUnifyRule {
-    public static final ProjectToProjectUnifyRule INSTANCE =
-        new ProjectToProjectUnifyRule();
+      final MutableCalc target = (MutableCalc) call.target;
+      final MutableScan targetInput = (MutableScan) target.getInput();
+      final Pair<RexNode, List<RexNode>> targetExplained = explainCalc(target);
+      final RexNode targetCond = targetExplained.left;
+      final List<RexNode> targetProjs = targetExplained.right;
 
-    private ProjectToProjectUnifyRule() {
-      super(operand(MutableProject.class, query(0)),
-          operand(MutableProject.class, target(0)), 1);
-    }
+      final RexBuilder rexBuilder = call.getCluster().getRexBuilder();
 
-    public UnifyResult apply(UnifyRuleCall call) {
-      final MutableProject target = (MutableProject) call.target;
-      final MutableProject query = (MutableProject) call.query;
-      final RexShuttle shuttle = getRexShuttle(target);
-      final List<RexNode> newProjects;
-      try {
-        newProjects = shuttle.apply(query.projects);
-      } catch (MatchFailed e) {
-        return null;
+      if (query.equals(targetInput) && targetCond.isAlwaysTrue()) {
 
 Review comment:
   Sure ~ that would be better ~

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