From 6302e6fa85be1d8d9efd8277f6a2bf43195776ac Mon Sep 17 00:00:00 2001
From: rubenada <rubenql@gmail.com>
Date: Thu, 8 Sep 2022 10:29:05 +0100
Subject: [PATCH] [CALCITE-5277] Make EnumerableRelImplementor
 stashedParameters order deterministic to increase BINDABLE_CACHE hit rate

---
 .../enumerable/EnumerableRelImplementor.java       | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableRelImplementor.java b/core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableRelImplementor.java
index 34386cd03064..2c82febd37ec 100644
--- a/core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableRelImplementor.java
+++ b/core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableRelImplementor.java
@@ -50,6 +50,7 @@
 import org.apache.calcite.util.BuiltInMethod;
 
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Equivalence;
 import com.google.common.collect.Collections2;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
@@ -64,7 +65,7 @@
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.IdentityHashMap;
+import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
@@ -80,8 +81,10 @@ public class EnumerableRelImplementor extends JavaRelImplementor {
   public final Map<String, Object> map;
   private final Map<String, RexToLixTranslator.InputGetter> corrVars =
       new HashMap<>();
-  private final IdentityHashMap<Object, ParameterExpression> stashedParameters =
-      new IdentityHashMap<>();
+  private static final Equivalence<Object> IDENTITY = Equivalence.identity();
+  // A combination of IdentityHashMap + LinkedHashMap to ensure deterministic order
+  private final Map<Equivalence.Wrapper<Object>, ParameterExpression> stashedParameters =
+      new LinkedHashMap<>();
 
   @SuppressWarnings("methodref.receiver.bound.invalid")
   protected final Function1<String, RexToLixTranslator.InputGetter> allCorrelateVariables =
@@ -439,7 +442,8 @@ public <T> Expression stash(T input, Class<? super T> clazz) {
         || input instanceof Double) {
       return Expressions.constant(input, clazz);
     }
-    ParameterExpression cached = stashedParameters.get(input);
+    final Equivalence.Wrapper<Object> key = IDENTITY.wrap(input);
+    ParameterExpression cached = stashedParameters.get(key);
     if (cached != null) {
       return cached;
     }
@@ -448,7 +452,7 @@ public <T> Expression stash(T input, Class<? super T> clazz) {
     final String name = "v" + map.size() + "stashed";
     final ParameterExpression x = Expressions.variable(clazz, name);
     map.put(name, input);
-    stashedParameters.put(input, x);
+    stashedParameters.put(key, x);
     return x;
   }