commit 84d3d32d1d76ce945f9c357c5b6f79119dae95f5
author leon <327030577@qq.com> Mon Jan 03 09:58:20 2022 +0800
committer GitHub <noreply@github.com> Sun Jan 02 20:58:20 2022 -0500
tree c13ff3d7e5aa6984dfce006a185700a2ee739235
parent ff1fc38e475892eefa812cddce4d2ae822335868

DRILL-8088: Improve expression evaluation performance (#2412)

* DRILL-8088: Improve expression evaluation performance

* fix checkstyle

exec/java-exec/src/main/java/org/apache/drill/exec/expr/EvaluationVisitor.java

diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/expr/EvaluationVisitor.java b/exec/java-exec/src/main/java/org/apache/drill/exec/expr/EvaluationVisitor.java
index 18b7af4..88eca6d 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/expr/EvaluationVisitor.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/expr/EvaluationVisitor.java
@@ -79,6 +79,7 @@
 import org.apache.drill.exec.vector.complex.reader.FieldReader;
 
 import org.apache.drill.shaded.guava.com.google.common.base.Function;
+import org.apache.drill.shaded.guava.com.google.common.collect.Maps;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -217,7 +218,7 @@
 
   void newScope() {
     mapStack.push(previousExpressions);
-    previousExpressions = new HashMap<>(previousExpressions);
+    previousExpressions = Maps.newHashMap();
   }
 
   void leaveScope() {
@@ -229,7 +230,17 @@
    * Get a HoldingContainer for the expression if it had been already evaluated
    */
   private HoldingContainer getPrevious(LogicalExpression expression, MappingSet mappingSet) {
-    HoldingContainer previous = previousExpressions.get(new ExpressionHolder(expression, mappingSet));
+    ExpressionHolder holder = new ExpressionHolder(expression, mappingSet);
+    HoldingContainer previous = null;
+    for (Map<ExpressionHolder,HoldingContainer> m : mapStack) {
+      previous = m.get(holder);
+      if (previous != null) {
+        break;
+      }
+    }
+    if (previous == null) {
+      previous = previousExpressions.get(holder);
+    }
     if (previous != null) {
       logger.debug("Found previously evaluated expression: {}", ExpressionStringBuilder.toString(expression));
     }