diff --git a/core/src/main/java/org/apache/calcite/rel/core/Correlate.java b/core/src/main/java/org/apache/calcite/rel/core/Correlate.java
index 7f94748be5d..76f3d119be0 100644
--- a/core/src/main/java/org/apache/calcite/rel/core/Correlate.java
+++ b/core/src/main/java/org/apache/calcite/rel/core/Correlate.java
@@ -108,7 +108,7 @@ public Correlate(RelInput input) {
     this(
         input.getCluster(), input.getTraitSet(), input.getInputs().get(0),
         input.getInputs().get(1),
-        new CorrelationId((Integer) input.get("correlationId")),
+        new CorrelationId((Integer) input.get("correlation")),
         input.getBitSet("requiredColumns"),
         input.getEnum("joinType", JoinRelType.class));
   }
@@ -158,7 +158,7 @@ public JoinRelType getJoinType() {
     return super.explainTerms(pw)
         .item("correlation", correlationId)
         .item("joinType", joinType.lowerName)
-        .item("requiredColumns", requiredColumns.toString());
+        .item("requiredColumns", requiredColumns);
   }
 
   /**
diff --git a/core/src/main/java/org/apache/calcite/rel/logical/LogicalCorrelate.java b/core/src/main/java/org/apache/calcite/rel/logical/LogicalCorrelate.java
index 137ca780651..1d67d6dfd19 100644
--- a/core/src/main/java/org/apache/calcite/rel/logical/LogicalCorrelate.java
+++ b/core/src/main/java/org/apache/calcite/rel/logical/LogicalCorrelate.java
@@ -80,7 +80,7 @@ public LogicalCorrelate(
   public LogicalCorrelate(RelInput input) {
     this(input.getCluster(), input.getTraitSet(), input.getInputs().get(0),
         input.getInputs().get(1),
-        new CorrelationId((Integer) input.get("correlationId")),
+        new CorrelationId((Integer) input.get("correlation")),
         input.getBitSet("requiredColumns"),
         input.getEnum("joinType", JoinRelType.class));
   }
diff --git a/core/src/test/java/org/apache/calcite/plan/RelWriterTest.java b/core/src/test/java/org/apache/calcite/plan/RelWriterTest.java
index 6ee9d97a677..701a136ff0d 100644
--- a/core/src/test/java/org/apache/calcite/plan/RelWriterTest.java
+++ b/core/src/test/java/org/apache/calcite/plan/RelWriterTest.java
@@ -21,6 +21,7 @@
 import org.apache.calcite.rel.RelNode;
 import org.apache.calcite.rel.RelShuttleImpl;
 import org.apache.calcite.rel.core.AggregateCall;
+import org.apache.calcite.rel.core.JoinRelType;
 import org.apache.calcite.rel.core.TableScan;
 import org.apache.calcite.rel.externalize.RelJsonReader;
 import org.apache.calcite.rel.externalize.RelJsonWriter;
@@ -32,6 +33,7 @@
 import org.apache.calcite.rel.type.RelDataType;
 import org.apache.calcite.rel.type.RelDataTypeField;
 import org.apache.calcite.rex.RexBuilder;
+import org.apache.calcite.rex.RexCorrelVariable;
 import org.apache.calcite.rex.RexFieldCollation;
 import org.apache.calcite.rex.RexInputRef;
 import org.apache.calcite.rex.RexProgramBuilder;
@@ -536,19 +538,7 @@ public class RelWriterTest {
     rel.explain(jsonWriter);
     String relJson = jsonWriter.asString();
     final RelOptSchema schema = getSchema(rel);
-    final String s =
-        Frameworks.withPlanner((cluster, relOptSchema, rootSchema) -> {
-          final RelJsonReader reader =
-              new RelJsonReader(cluster, schema, rootSchema);
-          RelNode node;
-          try {
-            node = reader.read(relJson);
-          } catch (IOException e) {
-            throw TestUtil.rethrow(e);
-          }
-          return RelOptUtil.dumpPlan("", node, SqlExplainFormat.TEXT,
-              SqlExplainLevel.EXPPLAN_ATTRIBUTES);
-        });
+    final String s = deserializeAndDumpToTextFormat(schema, relJson);
     final String expected = ""
         + "LogicalProject(trimmed_ename=[TRIM(FLAG(BOTH), ' ', $1)])\n"
         + "  LogicalTableScan(table=[[scott, EMP]])\n";
@@ -568,19 +558,7 @@ public class RelWriterTest {
     RelJsonWriter jsonWriter = new RelJsonWriter();
     rel.explain(jsonWriter);
     String relJson = jsonWriter.asString();
-    String s =
-        Frameworks.withPlanner((cluster, relOptSchema, rootSchema) -> {
-          final RelJsonReader reader = new RelJsonReader(
-              cluster, getSchema(rel), rootSchema);
-          RelNode node;
-          try {
-            node = reader.read(relJson);
-          } catch (IOException e) {
-            throw TestUtil.rethrow(e);
-          }
-          return RelOptUtil.dumpPlan("", node, SqlExplainFormat.TEXT,
-              SqlExplainLevel.EXPPLAN_ATTRIBUTES);
-        });
+    String s = deserializeAndDumpToTextFormat(getSchema(rel), relJson);
     final String expected = ""
         + "LogicalProject($f0=[+($5, 10)])\n"
         + "  LogicalTableScan(table=[[scott, EMP]])\n";
@@ -605,19 +583,7 @@ public class RelWriterTest {
     final RelJsonWriter jsonWriter = new RelJsonWriter();
     rel.explain(jsonWriter);
     final String relJson = jsonWriter.asString();
-    String s =
-        Frameworks.withPlanner((cluster, relOptSchema, rootSchema) -> {
-          final RelJsonReader reader = new RelJsonReader(
-              cluster, getSchema(rel), rootSchema);
-          RelNode node;
-          try {
-            node = reader.read(relJson);
-          } catch (IOException e) {
-            throw TestUtil.rethrow(e);
-          }
-          return RelOptUtil.dumpPlan("", node, SqlExplainFormat.TEXT,
-              SqlExplainLevel.EXPPLAN_ATTRIBUTES);
-        });
+    String s = deserializeAndDumpToTextFormat(getSchema(rel), relJson);
     final String expected = ""
         + "LogicalProject(max_sal=[$1])\n"
         + "  LogicalAggregate(group=[{0}], max_sal=[MAX($1)])\n"
@@ -645,19 +611,7 @@ public class RelWriterTest {
     final RelJsonWriter jsonWriter = new RelJsonWriter();
     rel.explain(jsonWriter);
     final String relJson = jsonWriter.asString();
-    String s =
-        Frameworks.withPlanner((cluster, relOptSchema, rootSchema) -> {
-          final RelJsonReader reader = new RelJsonReader(
-              cluster, getSchema(rel), rootSchema);
-          RelNode node;
-          try {
-            node = reader.read(relJson);
-          } catch (IOException e) {
-            throw TestUtil.rethrow(e);
-          }
-          return RelOptUtil.dumpPlan("", node, SqlExplainFormat.TEXT,
-              SqlExplainLevel.EXPPLAN_ATTRIBUTES);
-        });
+    String s = deserializeAndDumpToTextFormat(getSchema(rel), relJson);
     final String expected = ""
         + "LogicalProject($f1=[$1])\n"
         + "  LogicalAggregate(group=[{0}], agg#0=[MAX($1)])\n"
@@ -706,6 +660,32 @@ public class RelWriterTest {
     assertThat(s, isLinux(expected));
   }
 
+  @Test public void testCorrelateQuery() {
+    final FrameworkConfig config = RelBuilderTest.config().build();
+    final RelBuilder builder = RelBuilder.create(config);
+    final Holder<RexCorrelVariable> v = Holder.of(null);
+    RelNode relNode = builder.scan("EMP")
+        .variable(v)
+        .scan("DEPT")
+        .filter(
+            builder.equals(builder.field(0), builder.field(v.get(), "DEPTNO")))
+        .correlate(
+            JoinRelType.INNER, v.get().id, builder.field(2, 0, "DEPTNO"))
+        .build();
+    RelJsonWriter jsonWriter = new RelJsonWriter();
+    relNode.explain(jsonWriter);
+    final String relJson = jsonWriter.asString();
+    String s = deserializeAndDumpToTextFormat(getSchema(relNode), relJson);
+    final String expected = ""
+        + "LogicalCorrelate(correlation=[$cor0], joinType=[inner], requiredColumns=[{7}])\n"
+        + "  LogicalTableScan(table=[[scott, EMP]])\n"
+        + "  LogicalFilter(condition=[=($0, $cor0.DEPTNO)])\n"
+        + "    LogicalTableScan(table=[[scott, DEPT]])\n";
+
+    assertThat(s, isLinux(expected)
+    );
+  }
+
   /** Returns the schema of a {@link org.apache.calcite.rel.core.TableScan}
    * in this plan, or null if there are no scans. */
   private RelOptSchema getSchema(RelNode rel) {
@@ -719,6 +699,27 @@ private RelOptSchema getSchema(RelNode rel) {
         });
     return schemaHolder.get();
   }
+
+  /**
+   * Deserialize a relnode from the json string by {@link RelJsonReader},
+   * and dump it to text format.
+   */
+  private String deserializeAndDumpToTextFormat(RelOptSchema schema, String relJson) {
+    String s =
+        Frameworks.withPlanner((cluster, relOptSchema, rootSchema) -> {
+          final RelJsonReader reader = new RelJsonReader(
+              cluster, schema, rootSchema);
+          RelNode node;
+          try {
+            node = reader.read(relJson);
+          } catch (IOException e) {
+            throw TestUtil.rethrow(e);
+          }
+          return RelOptUtil.dumpPlan("", node, SqlExplainFormat.TEXT,
+              SqlExplainLevel.EXPPLAN_ATTRIBUTES);
+        });
+    return s;
+  }
 }
 
 // End RelWriterTest.java