diff --git a/core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableCalc.java b/core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableCalc.java
index 9e2018b5ff3..7777cd9d0be 100644
--- a/core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableCalc.java
+++ b/core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableCalc.java
@@ -151,7 +151,7 @@ public Result implement(EnumerableRelImplementor implementor, Prefer pref) {
             inputJavaType);
 
     final RexBuilder rexBuilder = getCluster().getRexBuilder();
-    final RelMetadataQuery mq = RelMetadataQuery.instance();
+    final RelMetadataQuery mq = getCluster().getMetadataQuery();
     final RelOptPredicateList predicates = mq.getPulledUpPredicates(child);
     final RexSimplify simplify =
         new RexSimplify(rexBuilder, predicates, false, RexUtil.EXECUTOR);
diff --git a/core/src/main/java/org/apache/calcite/plan/AbstractRelOptPlanner.java b/core/src/main/java/org/apache/calcite/plan/AbstractRelOptPlanner.java
index 81a297b1a3a..95eb6dcc4fd 100644
--- a/core/src/main/java/org/apache/calcite/plan/AbstractRelOptPlanner.java
+++ b/core/src/main/java/org/apache/calcite/plan/AbstractRelOptPlanner.java
@@ -246,7 +246,7 @@ public RelOptCost getCost(RelNode rel, RelMetadataQuery mq) {
 
   @SuppressWarnings("deprecation")
   public RelOptCost getCost(RelNode rel) {
-    final RelMetadataQuery mq = RelMetadataQuery.instance();
+    final RelMetadataQuery mq = rel.getCluster().getMetadataQuery();
     return getCost(rel, mq);
   }
 
diff --git a/core/src/main/java/org/apache/calcite/plan/RelOptUtil.java b/core/src/main/java/org/apache/calcite/plan/RelOptUtil.java
index 52407f85fbe..2fa519766be 100644
--- a/core/src/main/java/org/apache/calcite/plan/RelOptUtil.java
+++ b/core/src/main/java/org/apache/calcite/plan/RelOptUtil.java
@@ -227,7 +227,7 @@ public static Set<RelOptTable> findTables(RelNode rel) {
    */
   public static List<RelOptTable> findAllTables(RelNode rel) {
     final Multimap<Class<? extends RelNode>, RelNode> nodes =
-        RelMetadataQuery.instance().getNodeTypes(rel);
+        rel.getCluster().getMetadataQuery().getNodeTypes(rel);
     final List<RelOptTable> usedTables = new ArrayList<>();
     for (Entry<Class<? extends RelNode>, Collection<RelNode>> e : nodes.asMap().entrySet()) {
       if (TableScan.class.isAssignableFrom(e.getKey())) {
diff --git a/core/src/main/java/org/apache/calcite/plan/hep/HepPlanner.java b/core/src/main/java/org/apache/calcite/plan/hep/HepPlanner.java
index 410ef27a025..c256ebbc1a8 100644
--- a/core/src/main/java/org/apache/calcite/plan/hep/HepPlanner.java
+++ b/core/src/main/java/org/apache/calcite/plan/hep/HepPlanner.java
@@ -60,6 +60,8 @@
 import java.util.Map;
 import java.util.Set;
 
+import static org.apache.calcite.rel.metadata.RelMdUtil.clearCache;
+
 /**
  * HepPlanner is a heuristic implementation of the {@link RelOptPlanner}
  * interface.
@@ -812,6 +814,7 @@ private void contractVertices(
         }
         parentRel.replaceInput(i, preservedVertex);
       }
+      clearCache(parentRel);
       graph.removeEdge(parent, discardedVertex);
       graph.addEdge(parent, preservedVertex);
       updateVertex(parent, parentRel);
@@ -873,8 +876,9 @@ private RelNode buildFinalPlan(HepRelVertex vertex) {
       }
       child = buildFinalPlan((HepRelVertex) child);
       rel.replaceInput(i, child);
-      rel.recomputeDigest();
     }
+    clearCache(rel);
+    rel.recomputeDigest();
 
     return rel;
   }
diff --git a/core/src/main/java/org/apache/calcite/plan/volcano/RelSet.java b/core/src/main/java/org/apache/calcite/plan/volcano/RelSet.java
index 1205448abc5..9d615018f43 100644
--- a/core/src/main/java/org/apache/calcite/plan/volcano/RelSet.java
+++ b/core/src/main/java/org/apache/calcite/plan/volcano/RelSet.java
@@ -28,12 +28,14 @@
 import org.apache.calcite.util.trace.CalciteTrace;
 
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Maps;
 
 import org.slf4j.Logger;
 
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 
 /**
@@ -311,11 +313,14 @@ void mergeWith(
     assert otherSet.equivalentSet == null;
     LOGGER.trace("Merge set#{} into set#{}", otherSet.id, id);
     otherSet.equivalentSet = this;
+    final RelMetadataQuery mq = rel.getCluster().getMetadataQuery();
 
     // remove from table
     boolean existed = planner.allSets.remove(otherSet);
     assert existed : "merging with a dead otherSet";
 
+    final Map<RelSubset, RelNode> changedSubsets = Maps.newIdentityHashMap();
+
     // merge subsets
     for (RelSubset otherSubset : otherSet.subsets) {
       planner.ruleQueue.subsetImportances.remove(otherSubset);
@@ -323,9 +328,9 @@ void mergeWith(
           getOrCreateSubset(
               otherSubset.getCluster(),
               otherSubset.getTraitSet());
+      // collect RelSubset instances, whose best should be changed
       if (otherSubset.bestCost.isLt(subset.bestCost)) {
-        subset.bestCost = otherSubset.bestCost;
-        subset.best = otherSubset.best;
+        changedSubsets.put(subset, otherSubset.best);
       }
       for (RelNode otherRel : otherSubset.getRels()) {
         planner.reregister(this, otherRel);
@@ -335,6 +340,18 @@ void mergeWith(
     // Has another set merged with this?
     assert equivalentSet == null;
 
+    // calls propagateCostImprovements() for RelSubset instances,
+    // whose best should be changed to checks whether that
+    // subset's parents have gotten cheaper.
+    final Set<RelSubset> activeSet = new HashSet<>();
+    for (Map.Entry<RelSubset, RelNode> subsetBestPair : changedSubsets.entrySet()) {
+      RelSubset relSubset = subsetBestPair.getKey();
+      relSubset.propagateCostImprovements(
+          planner, mq, subsetBestPair.getValue(),
+          activeSet);
+    }
+    assert activeSet.isEmpty();
+
     // Update all rels which have a child in the other set, to reflect the
     // fact that the child has been renamed.
     //
@@ -353,8 +370,6 @@ void mergeWith(
     }
 
     // Make sure the cost changes as a result of merging are propagated.
-    final Set<RelSubset> activeSet = new HashSet<>();
-    final RelMetadataQuery mq = rel.getCluster().getMetadataQuery();
     for (RelNode parentRel : getParentRels()) {
       final RelSubset parentSubset = planner.getSubset(parentRel);
       parentSubset.propagateCostImprovements(
diff --git a/core/src/main/java/org/apache/calcite/plan/volcano/RelSubset.java b/core/src/main/java/org/apache/calcite/plan/volcano/RelSubset.java
index e55606356d9..85fcf825513 100644
--- a/core/src/main/java/org/apache/calcite/plan/volcano/RelSubset.java
+++ b/core/src/main/java/org/apache/calcite/plan/volcano/RelSubset.java
@@ -195,7 +195,8 @@ Set<RelNode> getParents() {
     final Set<RelNode> list = new LinkedHashSet<>();
     for (RelNode parent : set.getParentRels()) {
       for (RelSubset rel : inputSubsets(parent)) {
-        if (rel.set == set && traitSet.satisfies(rel.getTraitSet())) {
+        // see usage of this method in propagateCostImprovements0()
+        if (rel == this) {
           list.add(parent);
         }
       }
@@ -337,12 +338,17 @@ void propagateCostImprovements0(VolcanoPlanner planner, RelMetadataQuery mq,
 
         bestCost = cost;
         best = rel;
+        // since best was changed, cached metadata for this subset should be removed
+        mq.clearCache(this);
 
         // Lower cost means lower importance. Other nodes will change
         // too, but we'll get to them later.
         planner.ruleQueue.recompute(this);
         for (RelNode parent : getParents()) {
+          // removes parent cached metadata since its input was changed
+          mq.clearCache(parent);
           final RelSubset parentSubset = planner.getSubset(parent);
+          // parent subset will clear its cache in propagateCostImprovements0 method itself
           parentSubset.propagateCostImprovements(planner, mq, parent,
               activeSet);
         }
diff --git a/core/src/main/java/org/apache/calcite/plan/volcano/VolcanoPlanner.java b/core/src/main/java/org/apache/calcite/plan/volcano/VolcanoPlanner.java
index 281e4728a2b..f3e3a1dc830 100644
--- a/core/src/main/java/org/apache/calcite/plan/volcano/VolcanoPlanner.java
+++ b/core/src/main/java/org/apache/calcite/plan/volcano/VolcanoPlanner.java
@@ -94,6 +94,8 @@
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
+import static org.apache.calcite.rel.metadata.RelMdUtil.clearCache;
+
 /**
  * VolcanoPlanner optimizes queries by transforming expressions selectively
  * according to a dynamic programming algorithm.
@@ -1382,6 +1384,7 @@ private boolean fixUpInputs(RelNode rel) {
         }
       }
     }
+    clearCache(rel);
     return changeCount > 0;
   }
 
diff --git a/core/src/main/java/org/apache/calcite/prepare/CalciteMaterializer.java b/core/src/main/java/org/apache/calcite/prepare/CalciteMaterializer.java
index 92cb104b8a4..8449d44a9b8 100644
--- a/core/src/main/java/org/apache/calcite/prepare/CalciteMaterializer.java
+++ b/core/src/main/java/org/apache/calcite/prepare/CalciteMaterializer.java
@@ -20,8 +20,8 @@
 import org.apache.calcite.interpreter.BindableConvention;
 import org.apache.calcite.jdbc.CalcitePrepare;
 import org.apache.calcite.jdbc.CalciteSchema;
+import org.apache.calcite.plan.RelOptCluster;
 import org.apache.calcite.plan.RelOptMaterialization;
-import org.apache.calcite.plan.RelOptPlanner;
 import org.apache.calcite.plan.RelOptTable;
 import org.apache.calcite.plan.RelOptUtil;
 import org.apache.calcite.rel.RelNode;
@@ -61,10 +61,10 @@ class CalciteMaterializer extends CalcitePrepareImpl.CalcitePreparingStmt {
   CalciteMaterializer(CalcitePrepareImpl prepare,
       CalcitePrepare.Context context,
       CatalogReader catalogReader, CalciteSchema schema,
-      RelOptPlanner planner, SqlRexConvertletTable convertletTable) {
+      SqlRexConvertletTable convertletTable, RelOptCluster cluster) {
     super(prepare, context, catalogReader, catalogReader.getTypeFactory(),
-        schema, EnumerableRel.Prefer.ANY, planner, BindableConvention.INSTANCE,
-        convertletTable);
+        schema, EnumerableRel.Prefer.ANY, BindableConvention.INSTANCE,
+        convertletTable, cluster);
   }
 
   /** Populates a materialization record, converting a table path
diff --git a/core/src/main/java/org/apache/calcite/prepare/CalcitePrepareImpl.java b/core/src/main/java/org/apache/calcite/prepare/CalcitePrepareImpl.java
index 8f2bdff723b..60ff2b973a3 100644
--- a/core/src/main/java/org/apache/calcite/prepare/CalcitePrepareImpl.java
+++ b/core/src/main/java/org/apache/calcite/prepare/CalcitePrepareImpl.java
@@ -314,8 +314,8 @@ private ParseResult convert_(Context context, String sql, boolean analyze,
 
     final CalcitePreparingStmt preparingStmt =
         new CalcitePreparingStmt(this, context, catalogReader, typeFactory,
-            context.getRootSchema(), null, planner, resultConvention,
-            createConvertletTable());
+            context.getRootSchema(), null, resultConvention, createConvertletTable(),
+            createCluster(planner, new RexBuilder(typeFactory)));
     final SqlToRelConverter converter =
         preparingStmt.getSqlToRelConverter(validator, catalogReader,
             configBuilder.build());
@@ -731,8 +731,8 @@ <T> CalciteSignature<T> prepare2_(
             : EnumerableConvention.INSTANCE;
     final CalcitePreparingStmt preparingStmt =
         new CalcitePreparingStmt(this, context, catalogReader, typeFactory,
-            context.getRootSchema(), prefer, planner, resultConvention,
-            createConvertletTable());
+            context.getRootSchema(), prefer, resultConvention, createConvertletTable(),
+            createCluster(planner, new RexBuilder(typeFactory)));
 
     final RelDataType x;
     final Prepare.PreparedResult preparedResult;
@@ -998,7 +998,7 @@ private static String getTypeName(RelDataType type) {
   }
 
   protected void populateMaterializations(Context context,
-      RelOptPlanner planner, Prepare.Materialization materialization) {
+      Prepare.Materialization materialization, RelOptCluster cluster) {
     // REVIEW: initialize queryRel and tableRel inside MaterializationService,
     // not here?
     try {
@@ -1010,8 +1010,8 @@ protected void populateMaterializations(Context context,
               context.getTypeFactory(),
               context.config());
       final CalciteMaterializer materializer =
-          new CalciteMaterializer(this, context, catalogReader, schema, planner,
-              createConvertletTable());
+          new CalciteMaterializer(this, context, catalogReader, schema,
+              createConvertletTable(), cluster);
       materializer.populate(materialization);
     } catch (Exception e) {
       throw new RuntimeException("While populating materialization "
@@ -1063,6 +1063,7 @@ static class CalcitePreparingStmt extends Prepare
     protected final RelDataTypeFactory typeFactory;
     protected final SqlRexConvertletTable convertletTable;
     private final EnumerableRel.Prefer prefer;
+    private final RelOptCluster cluster;
     private final Map<String, Object> internalParameters =
         Maps.newLinkedHashMap();
     private int expansionDepth;
@@ -1074,17 +1075,18 @@ static class CalcitePreparingStmt extends Prepare
         RelDataTypeFactory typeFactory,
         CalciteSchema schema,
         EnumerableRel.Prefer prefer,
-        RelOptPlanner planner,
         Convention resultConvention,
-        SqlRexConvertletTable convertletTable) {
+        SqlRexConvertletTable convertletTable,
+        RelOptCluster cluster) {
       super(context, catalogReader, resultConvention);
       this.prepare = prepare;
       this.schema = schema;
       this.prefer = prefer;
-      this.planner = planner;
+      this.cluster = cluster;
+      this.planner = cluster.getPlanner();
+      this.rexBuilder = cluster.getRexBuilder();
       this.typeFactory = typeFactory;
       this.convertletTable = convertletTable;
-      this.rexBuilder = new RexBuilder(typeFactory);
     }
 
     @Override protected void init(Class runtimeContextClass) {
@@ -1096,8 +1098,6 @@ public PreparedResult prepareQueryable(
       return prepare_(
           new Supplier<RelNode>() {
             public RelNode get() {
-              final RelOptCluster cluster =
-                  prepare.createCluster(planner, rexBuilder);
               return new LixToRelTranslator(cluster, CalcitePreparingStmt.this)
                   .translate(queryable);
             }
@@ -1161,7 +1161,6 @@ private PreparedResult prepare_(Supplier<RelNode> fn,
         SqlValidator validator,
         CatalogReader catalogReader,
         SqlToRelConverter.Config config) {
-      final RelOptCluster cluster = prepare.createCluster(planner, rexBuilder);
       return new SqlToRelConverter(this, validator, catalogReader, cluster,
           convertletTable, config);
     }
@@ -1296,7 +1295,7 @@ public Type getElementType() {
               ? MaterializationService.instance().query(schema)
               : ImmutableList.<Prepare.Materialization>of();
       for (Prepare.Materialization materialization : materializations) {
-        prepare.populateMaterializations(context, planner, materialization);
+        prepare.populateMaterializations(context, materialization, cluster);
       }
       return materializations;
     }
diff --git a/core/src/main/java/org/apache/calcite/rel/AbstractRelNode.java b/core/src/main/java/org/apache/calcite/rel/AbstractRelNode.java
index 3b6be139053..68a9fbbe7df 100644
--- a/core/src/main/java/org/apache/calcite/rel/AbstractRelNode.java
+++ b/core/src/main/java/org/apache/calcite/rel/AbstractRelNode.java
@@ -163,13 +163,13 @@ public String getCorrelVariable() {
 
   @SuppressWarnings("deprecation")
   public boolean isDistinct() {
-    final RelMetadataQuery mq = RelMetadataQuery.instance();
+    final RelMetadataQuery mq = cluster.getMetadataQuery();
     return Boolean.TRUE.equals(mq.areRowsUnique(this));
   }
 
   @SuppressWarnings("deprecation")
   public boolean isKey(ImmutableBitSet columns) {
-    final RelMetadataQuery mq = RelMetadataQuery.instance();
+    final RelMetadataQuery mq = cluster.getMetadataQuery();
     return Boolean.TRUE.equals(mq.areColumnsUnique(this, columns));
   }
 
@@ -243,7 +243,7 @@ public List<RelNode> getInputs() {
 
   @SuppressWarnings("deprecation")
   public final double getRows() {
-    return estimateRowCount(RelMetadataQuery.instance());
+    return estimateRowCount(cluster.getMetadataQuery());
   }
 
   public double estimateRowCount(RelMetadataQuery mq) {
@@ -285,7 +285,7 @@ public RelNode accept(RexShuttle shuttle) {
 
   @SuppressWarnings("deprecation")
   public final RelOptCost computeSelfCost(RelOptPlanner planner) {
-    return computeSelfCost(planner, RelMetadataQuery.instance());
+    return computeSelfCost(planner, cluster.getMetadataQuery());
   }
 
   public RelOptCost computeSelfCost(RelOptPlanner planner,
diff --git a/core/src/main/java/org/apache/calcite/rel/core/Filter.java b/core/src/main/java/org/apache/calcite/rel/core/Filter.java
index 492ab27b776..c77d5b7bb44 100644
--- a/core/src/main/java/org/apache/calcite/rel/core/Filter.java
+++ b/core/src/main/java/org/apache/calcite/rel/core/Filter.java
@@ -138,13 +138,13 @@ public RexNode getCondition() {
 
   @Deprecated // to be removed before 2.0
   public static double estimateFilteredRows(RelNode child, RexProgram program) {
-    final RelMetadataQuery mq = RelMetadataQuery.instance();
+    final RelMetadataQuery mq = child.getCluster().getMetadataQuery();
     return RelMdUtil.estimateFilteredRows(child, program, mq);
   }
 
   @Deprecated // to be removed before 2.0
   public static double estimateFilteredRows(RelNode child, RexNode condition) {
-    final RelMetadataQuery mq = RelMetadataQuery.instance();
+    final RelMetadataQuery mq = child.getCluster().getMetadataQuery();
     return RelMdUtil.estimateFilteredRows(child, condition, mq);
   }
 
diff --git a/core/src/main/java/org/apache/calcite/rel/core/Join.java b/core/src/main/java/org/apache/calcite/rel/core/Join.java
index a9e0441dab1..d9ad28b8275 100644
--- a/core/src/main/java/org/apache/calcite/rel/core/Join.java
+++ b/core/src/main/java/org/apache/calcite/rel/core/Join.java
@@ -189,7 +189,7 @@ public JoinRelType getJoinType() {
   public static double estimateJoinedRows(
       Join joinRel,
       RexNode condition) {
-    final RelMetadataQuery mq = RelMetadataQuery.instance();
+    final RelMetadataQuery mq = joinRel.getCluster().getMetadataQuery();
     return Util.first(RelMdUtil.getJoinRowCount(mq, joinRel, condition), 1D);
   }
 
diff --git a/core/src/main/java/org/apache/calcite/rel/core/Union.java b/core/src/main/java/org/apache/calcite/rel/core/Union.java
index 942df4a744f..7bc755ae973 100644
--- a/core/src/main/java/org/apache/calcite/rel/core/Union.java
+++ b/core/src/main/java/org/apache/calcite/rel/core/Union.java
@@ -62,7 +62,7 @@ protected Union(RelInput input) {
 
   @Deprecated // to be removed before 2.0
   public static double estimateRowCount(RelNode rel) {
-    final RelMetadataQuery mq = RelMetadataQuery.instance();
+    final RelMetadataQuery mq = rel.getCluster().getMetadataQuery();
     return RelMdUtil.getUnionAllRowCount(mq, (Union) rel);
   }
 }
diff --git a/core/src/main/java/org/apache/calcite/rel/metadata/JaninoRelMetadataProvider.java b/core/src/main/java/org/apache/calcite/rel/metadata/JaninoRelMetadataProvider.java
index 634da056ad9..6d3e462d882 100644
--- a/core/src/main/java/org/apache/calcite/rel/metadata/JaninoRelMetadataProvider.java
+++ b/core/src/main/java/org/apache/calcite/rel/metadata/JaninoRelMetadataProvider.java
@@ -274,10 +274,9 @@ private static <M extends Metadata> MetadataHandler<M> load3(
             .append(method.i)
             .append(")");
       }
-      buff.append(", r");
       safeArgList(buff, method.e)
           .append(");\n")
-          .append("    final Object v = mq.map.get(key);\n")
+          .append("    final Object v = mq.map.get(r, key);\n")
           .append("    if (v != null) {\n")
           .append("      if (v == ")
           .append(NullSentinel.class.getName())
@@ -295,7 +294,7 @@ private static <M extends Metadata> MetadataHandler<M> load3(
           .append(method.e.getReturnType().getName())
           .append(") v;\n")
           .append("    }\n")
-          .append("    mq.map.put(key,")
+          .append("    mq.map.put(r, key,")
           .append(NullSentinel.class.getName())
           .append(".ACTIVE);\n")
           .append("    try {\n")
@@ -306,14 +305,14 @@ private static <M extends Metadata> MetadataHandler<M> load3(
           .append("_(r, mq");
       argList(buff, method.e)
           .append(");\n")
-          .append("      mq.map.put(key, ")
+          .append("      mq.map.put(r, key, ")
           .append(NullSentinel.class.getName())
           .append(".mask(x));\n")
           .append("      return x;\n")
           .append("    } catch (")
           .append(Exception.class.getName())
           .append(" e) {\n")
-          .append("      mq.map.remove(key);\n")
+          .append("      mq.map.row(r).clear();\n")
           .append("      throw e;\n")
           .append("    }\n")
           .append("  }\n")
diff --git a/core/src/main/java/org/apache/calcite/rel/metadata/ReflectiveRelMetadataProvider.java b/core/src/main/java/org/apache/calcite/rel/metadata/ReflectiveRelMetadataProvider.java
index 9b5abecd5b7..db8cb44f2e4 100644
--- a/core/src/main/java/org/apache/calcite/rel/metadata/ReflectiveRelMetadataProvider.java
+++ b/core/src/main/java/org/apache/calcite/rel/metadata/ReflectiveRelMetadataProvider.java
@@ -188,7 +188,7 @@ public Object invoke(Object proxy, Method method,
                         }
                         key = FlatLists.copyOf(args2);
                       }
-                      if (mq.map.put(key, NullSentinel.INSTANCE) != null) {
+                      if (mq.map.put(rel, key, NullSentinel.INSTANCE) != null) {
                         throw CyclicMetadataException.INSTANCE;
                       }
                       try {
@@ -198,7 +198,7 @@ public Object invoke(Object proxy, Method method,
                         Util.throwIfUnchecked(e.getCause());
                         throw new RuntimeException(e.getCause());
                       } finally {
-                        mq.map.remove(key);
+                        mq.map.remove(rel, key);
                       }
                     }
                   });
diff --git a/core/src/main/java/org/apache/calcite/rel/metadata/RelMdUtil.java b/core/src/main/java/org/apache/calcite/rel/metadata/RelMdUtil.java
index 6229f4e3a3f..64cd9a01099 100644
--- a/core/src/main/java/org/apache/calcite/rel/metadata/RelMdUtil.java
+++ b/core/src/main/java/org/apache/calcite/rel/metadata/RelMdUtil.java
@@ -842,6 +842,15 @@ public static boolean checkInputForCollationAndLimit(RelMetadataQuery mq,
     }
     return alreadySorted && alreadySmaller;
   }
+
+  /**
+   * Removes cached metadata values for specified RelNode.
+   *
+   * @param rel RelNode whose cached metadata should be removed
+   */
+  public static void clearCache(RelNode rel) {
+    rel.getCluster().getMetadataQuery().clearCache(rel);
+  }
 }
 
 // End RelMdUtil.java
diff --git a/core/src/main/java/org/apache/calcite/rel/metadata/RelMetadataQuery.java b/core/src/main/java/org/apache/calcite/rel/metadata/RelMetadataQuery.java
index 06c4fb04de1..441f1546feb 100644
--- a/core/src/main/java/org/apache/calcite/rel/metadata/RelMetadataQuery.java
+++ b/core/src/main/java/org/apache/calcite/rel/metadata/RelMetadataQuery.java
@@ -28,17 +28,17 @@
 import org.apache.calcite.util.ImmutableBitSet;
 
 import com.google.common.base.Preconditions;
+import com.google.common.collect.HashBasedTable;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Multimap;
+import com.google.common.collect.Table;
 
 import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.Method;
 import java.lang.reflect.Proxy;
 import java.util.Collections;
-import java.util.HashMap;
 import java.util.List;
-import java.util.Map;
 import java.util.Set;
 
 /**
@@ -78,7 +78,7 @@
  */
 public class RelMetadataQuery {
   /** Set of active metadata queries, and cache of previous results. */
-  public final Map<List, Object> map = new HashMap<>();
+  public final Table<RelNode, List, Object> map = HashBasedTable.create();
 
   public final JaninoRelMetadataProvider metadataProvider;
 
@@ -848,6 +848,15 @@ public boolean isVisibleInExplain(RelNode rel,
     }
   }
 
+  /**
+   * Removes cached metadata values for specified RelNode.
+   *
+   * @param rel RelNode whose cached metadata should be removed
+   */
+  public void clearCache(RelNode rel) {
+    map.row(rel).clear();
+  }
+
   private static Double validatePercentage(Double result) {
     assert isPercentage(result, true);
     return result;
diff --git a/core/src/main/java/org/apache/calcite/rel/rules/AbstractMaterializedViewRule.java b/core/src/main/java/org/apache/calcite/rel/rules/AbstractMaterializedViewRule.java
index 3d997cbd688..19fd1cc2a33 100644
--- a/core/src/main/java/org/apache/calcite/rel/rules/AbstractMaterializedViewRule.java
+++ b/core/src/main/java/org/apache/calcite/rel/rules/AbstractMaterializedViewRule.java
@@ -175,7 +175,7 @@ protected AbstractMaterializedViewRule(RelOptRuleOperand operand,
    */
   protected void perform(RelOptRuleCall call, Project topProject, RelNode node) {
     final RexBuilder rexBuilder = node.getCluster().getRexBuilder();
-    final RelMetadataQuery mq = RelMetadataQuery.instance();
+    final RelMetadataQuery mq = call.getMetadataQuery();
     final RelOptPlanner planner = call.getPlanner();
     final RexExecutor executor =
         Util.first(planner.getExecutor(), RexUtil.EXECUTOR);