diff --git a/asterixdb/asterix-algebra/src/main/javacc/AQLPlusExtension.jj b/asterixdb/asterix-algebra/src/main/javacc/AQLPlusExtension.jj
index c3cfdb1..35e8ff0 100644
--- a/asterixdb/asterix-algebra/src/main/javacc/AQLPlusExtension.jj
+++ b/asterixdb/asterix-algebra/src/main/javacc/AQLPlusExtension.jj
@@ -106,30 +106,24 @@
 @new
 Clause MetaVariableClause() throws ParseException :
 {
-    MetaVariableClause mc = new MetaVariableClause();
-    VarIdentifier var = new VarIdentifier();
 }
 {
     <METAVARIABLECLAUSE>
     {
-      mc.setVar(var);
-      var.setValue(token.image);
-      return mc;
+      VarIdentifier var = new VarIdentifier(token.image);
+      return new MetaVariableClause(var);
     }
 }
 
 @new
 MetaVariableExpr MetaVariableRef() throws ParseException:
 {
-    MetaVariableExpr metaVarExp = new MetaVariableExpr();
-    VarIdentifier var = new VarIdentifier();
 }
 {
-      <METAVARIABLE>
+    <METAVARIABLE>
     {
-     metaVarExp.setVar(var);
-     var.setValue(token.image);
-     return metaVarExp;
+      VarIdentifier var = new VarIdentifier(token.image);
+      return new MetaVariableExpr(var);
     }
 }
 
diff --git a/asterixdb/asterix-app/src/main/java/org/apache/asterix/app/translator/QueryTranslator.java b/asterixdb/asterix-app/src/main/java/org/apache/asterix/app/translator/QueryTranslator.java
index aed358e..60471f1 100644
--- a/asterixdb/asterix-app/src/main/java/org/apache/asterix/app/translator/QueryTranslator.java
+++ b/asterixdb/asterix-app/src/main/java/org/apache/asterix/app/translator/QueryTranslator.java
@@ -557,11 +557,20 @@
         SourceLocation sourceLoc = dd.getSourceLocation();
         String dataverseName = getActiveDataverse(dd.getDataverse());
         String datasetName = dd.getName().getValue();
+        String datasetFullyQualifiedName = dataverseName + "." + datasetName;
         DatasetType dsType = dd.getDatasetType();
         String itemTypeDataverseName = getActiveDataverse(dd.getItemTypeDataverse());
         String itemTypeName = dd.getItemTypeName().getValue();
-        String metaItemTypeDataverseName = getActiveDataverse(dd.getMetaItemTypeDataverse());
-        String metaItemTypeName = dd.getMetaItemTypeName().getValue();
+        String itemTypeFullyQualifiedName = itemTypeDataverseName + "." + itemTypeName;
+        String metaItemTypeDataverseName = null;
+        String metaItemTypeName = null;
+        String metaItemTypeFullyQualifiedName = null;
+        Identifier metaItemTypeId = dd.getMetaItemTypeName();
+        if (metaItemTypeId != null) {
+            metaItemTypeName = metaItemTypeId.getValue();
+            metaItemTypeDataverseName = getActiveDataverse(dd.getMetaItemTypeDataverse());
+            metaItemTypeFullyQualifiedName = metaItemTypeDataverseName + "." + metaItemTypeName;
+        }
         Identifier ngNameId = dd.getNodegroupName();
         String nodegroupName = ngNameId == null ? null : ngNameId.getValue();
         String compactionPolicy = dd.getCompactionPolicy();
@@ -573,12 +582,12 @@
         boolean bActiveTxn = true;
         metadataProvider.setMetadataTxnContext(mdTxnCtx);
         MetadataLockUtil.createDatasetBegin(lockManager, metadataProvider.getLocks(), dataverseName,
-                itemTypeDataverseName, itemTypeDataverseName + "." + itemTypeName, metaItemTypeDataverseName,
-                metaItemTypeDataverseName + "." + metaItemTypeName, nodegroupName, compactionPolicy,
-                dataverseName + "." + datasetName, defaultCompactionPolicy);
+                itemTypeDataverseName, itemTypeFullyQualifiedName, metaItemTypeDataverseName,
+                metaItemTypeFullyQualifiedName, nodegroupName, compactionPolicy, datasetFullyQualifiedName,
+                defaultCompactionPolicy);
         Dataset dataset = null;
         try {
-            IDatasetDetails datasetDetails = null;
+            IDatasetDetails datasetDetails;
             Dataset ds = metadataProvider.findDataset(dataverseName, datasetName);
             if (ds != null) {
                 if (dd.getIfNotExists()) {
@@ -1372,8 +1381,8 @@
                 }
             }
 
-            if (activeDataverse != null && activeDataverse.getDataverseName() == dataverseName) {
-                activeDataverse = null;
+            if (activeDataverse.getDataverseName().equals(dataverseName)) {
+                activeDataverse = MetadataBuiltinEntities.DEFAULT_DATAVERSE;
             }
             MetadataManager.INSTANCE.commitTransaction(mdTxnCtx);
             return true;
@@ -1383,8 +1392,8 @@
             }
 
             if (progress == ProgressState.ADDED_PENDINGOP_RECORD_TO_METADATA) {
-                if (activeDataverse != null && activeDataverse.getDataverseName() == dataverseName) {
-                    activeDataverse = null;
+                if (activeDataverse.getDataverseName().equals(dataverseName)) {
+                    activeDataverse = MetadataBuiltinEntities.DEFAULT_DATAVERSE;
                 }
 
                 // #. execute compensation operations
diff --git a/asterixdb/asterix-lang-aql/src/main/java/org/apache/asterix/lang/aql/clause/ForClause.java b/asterixdb/asterix-lang-aql/src/main/java/org/apache/asterix/lang/aql/clause/ForClause.java
index 9bae2a0..39ad04f 100644
--- a/asterixdb/asterix-lang-aql/src/main/java/org/apache/asterix/lang/aql/clause/ForClause.java
+++ b/asterixdb/asterix-lang-aql/src/main/java/org/apache/asterix/lang/aql/clause/ForClause.java
@@ -31,17 +31,14 @@
     private Expression inExpr = null;
 
     public ForClause() {
-        super();
     }
 
     public ForClause(VariableExpr varExpr, Expression inExpr) {
-        super();
         this.varExpr = varExpr;
         this.inExpr = inExpr;
     }
 
     public ForClause(VariableExpr varExpr, Expression inExpr, VariableExpr posExpr) {
-        super();
         this.varExpr = varExpr;
         this.inExpr = inExpr;
         this.posExpr = posExpr;
diff --git a/asterixdb/asterix-lang-aql/src/main/java/org/apache/asterix/lang/aql/clause/MetaVariableClause.java b/asterixdb/asterix-lang-aql/src/main/java/org/apache/asterix/lang/aql/clause/MetaVariableClause.java
index 7712cf9..bbf7269 100644
--- a/asterixdb/asterix-lang-aql/src/main/java/org/apache/asterix/lang/aql/clause/MetaVariableClause.java
+++ b/asterixdb/asterix-lang-aql/src/main/java/org/apache/asterix/lang/aql/clause/MetaVariableClause.java
@@ -27,6 +27,13 @@
 public class MetaVariableClause extends AbstractClause {
     private VarIdentifier var;
 
+    public MetaVariableClause() {
+    }
+
+    public MetaVariableClause(VarIdentifier var) {
+        this.var = var;
+    }
+
     @Override
     public <R, T> R accept(ILangVisitor<R, T> visitor, T arg) throws CompilationException {
         return ((IAQLPlusVisitor<R, T>) visitor).visitMetaVariableClause(this, arg);
diff --git a/asterixdb/asterix-lang-aql/src/main/java/org/apache/asterix/lang/aql/expression/MetaVariableExpr.java b/asterixdb/asterix-lang-aql/src/main/java/org/apache/asterix/lang/aql/expression/MetaVariableExpr.java
index 2964eff..fb03312 100644
--- a/asterixdb/asterix-lang-aql/src/main/java/org/apache/asterix/lang/aql/expression/MetaVariableExpr.java
+++ b/asterixdb/asterix-lang-aql/src/main/java/org/apache/asterix/lang/aql/expression/MetaVariableExpr.java
@@ -21,10 +21,15 @@
 import org.apache.asterix.common.exceptions.CompilationException;
 import org.apache.asterix.lang.aql.visitor.base.IAQLPlusVisitor;
 import org.apache.asterix.lang.common.expression.VariableExpr;
+import org.apache.asterix.lang.common.struct.VarIdentifier;
 import org.apache.asterix.lang.common.visitor.base.ILangVisitor;
 
 public class MetaVariableExpr extends VariableExpr {
 
+    public MetaVariableExpr(VarIdentifier var) {
+        super(var);
+    }
+
     @Override
     public <R, T> R accept(ILangVisitor<R, T> visitor, T arg) throws CompilationException {
         return ((IAQLPlusVisitor<R, T>) visitor).visitMetaVariableExpr(this, arg);
diff --git a/asterixdb/asterix-lang-aql/src/main/javacc/AQL.jj b/asterixdb/asterix-lang-aql/src/main/javacc/AQL.jj
index 3bb70c1..810d8e9 100644
--- a/asterixdb/asterix-lang-aql/src/main/javacc/AQL.jj
+++ b/asterixdb/asterix-lang-aql/src/main/javacc/AQL.jj
@@ -152,6 +152,7 @@
 import org.apache.asterix.lang.common.struct.VarIdentifier;
 import org.apache.asterix.lang.common.util.RangeMapBuilder;
 import org.apache.asterix.metadata.utils.MetadataConstants;
+import org.apache.asterix.om.types.BuiltinType;
 import org.apache.hyracks.algebricks.common.utils.Pair;
 import org.apache.hyracks.algebricks.common.utils.Triple;
 import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
@@ -184,6 +185,8 @@
     // data generator hints
     private static final String DGEN_HINT = "dgen";
 
+    private static final String INT_TYPE_NAME = "int";
+
     private static class IndexParams {
       public IndexType type;
       public int gramLength;
@@ -797,15 +800,13 @@
 {
   <LEFTPAREN> (<VARIABLE>
     {
-      var = new VarIdentifier();
-      var.setValue(token.image);
+      var = new VarIdentifier(token.image);
       paramList.add(var);
       getCurrentScope().addNewVarSymbolToScope(var);
     }
   ( <COMMA> <VARIABLE>
     {
-      var = new VarIdentifier();
-      var.setValue(token.image);
+      var = new VarIdentifier(token.image);
       paramList.add(var);
       getCurrentScope().addNewVarSymbolToScope(var);
     }
@@ -1386,8 +1387,8 @@
 {
  id = QualifiedName()
    {
-     if (id.first == null && id.second.getValue().equalsIgnoreCase("int")) {
-        id.second.setValue("int64");
+     if (id.first == null && id.second.getValue().equalsIgnoreCase(INT_TYPE_NAME)) {
+        id.second = new Identifier(BuiltinType.AINT64.getTypeName());
      }
 
      return new TypeReferenceExpression(id);
@@ -1460,8 +1461,8 @@
         result.function  = third;
       }
 
-      if (result.function.equalsIgnoreCase("int")) {
-            result.function = "int64";
+      if (result.function.equalsIgnoreCase(INT_TYPE_NAME)) {
+        result.function = BuiltinType.AINT64.getTypeName();
       }
       return result;
     }
@@ -2086,8 +2087,6 @@
 
 VariableExpr VariableRef() throws ParseException:
 {
-    VariableExpr varExp = new VariableExpr();
-    VarIdentifier var = new VarIdentifier();
 }
 {
   <VARIABLE>
@@ -2097,13 +2096,13 @@
      if (isInForbiddenScopes(varName)) {
        throw new ParseException("Inside limit clauses, it is disallowed to reference a variable having the same name as any variable bound in the same scope as the limit clause.");
      }
+     VariableExpr varExp;
      if(ident != null) { // exist such ident
+       varExp = new VariableExpr((VarIdentifier)ident);
        varExp.setIsNewVar(false);
-       varExp.setVar((VarIdentifier)ident);
      } else {
-       varExp.setVar(var);
+       varExp = new VariableExpr(new VarIdentifier(varName));
      }
-     var.setValue(varName);
      return varExp;
     }
 }
@@ -2111,18 +2110,16 @@
 
 VariableExpr Variable() throws ParseException:
 {
-    VariableExpr varExp = new VariableExpr();
-    VarIdentifier var = new VarIdentifier();
 }
 {
   <VARIABLE>
     {
-     Identifier ident = lookupSymbol(token.image);
+     String varName = token.image;
+     Identifier ident = lookupSymbol(varName);
+     VariableExpr varExp = new VariableExpr(new VarIdentifier(varName));
      if(ident != null) { // exist such ident
        varExp.setIsNewVar(false);
      }
-     varExp.setVar(var);
-     var.setValue(token.image);
      return varExp;
     }
 }
diff --git a/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/expression/VariableExpr.java b/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/expression/VariableExpr.java
index 17d0d2f..3ed3221 100644
--- a/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/expression/VariableExpr.java
+++ b/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/expression/VariableExpr.java
@@ -29,11 +29,6 @@
     private VarIdentifier var;
     private boolean isNewVar;
 
-    public VariableExpr() {
-        super();
-        isNewVar = true;
-    }
-
     public VariableExpr(VarIdentifier var) {
         super();
         this.var = var;
diff --git a/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/statement/DatasetDecl.java b/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/statement/DatasetDecl.java
index 0a17b24..ac019fc 100644
--- a/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/statement/DatasetDecl.java
+++ b/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/statement/DatasetDecl.java
@@ -101,16 +101,12 @@
         }
     }
 
-    public Identifier getMetaName() {
-        return name;
-    }
-
     public Identifier getMetaItemTypeName() {
-        return metaItemTypeName == null ? new Identifier() : metaItemTypeName;
+        return metaItemTypeName;
     }
 
     public Identifier getMetaItemTypeDataverse() {
-        return metaItemTypeDataverse == null ? new Identifier() : metaItemTypeDataverse;
+        return metaItemTypeDataverse;
     }
 
     public String getQualifiedMetaTypeName() {
diff --git a/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/struct/Identifier.java b/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/struct/Identifier.java
index 1443833..7f8171c 100644
--- a/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/struct/Identifier.java
+++ b/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/struct/Identifier.java
@@ -21,11 +21,8 @@
 import java.util.Objects;
 
 public class Identifier {
-    protected String value;
 
-    public Identifier() {
-        // default constructor.
-    }
+    protected final String value;
 
     public Identifier(String value) {
         this.value = value;
@@ -35,10 +32,6 @@
         return value;
     }
 
-    public final void setValue(String value) {
-        this.value = value;
-    }
-
     @Override
     public String toString() {
         return value;
diff --git a/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/struct/VarIdentifier.java b/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/struct/VarIdentifier.java
index 587dd1c..4fea88b 100644
--- a/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/struct/VarIdentifier.java
+++ b/asterixdb/asterix-lang-common/src/main/java/org/apache/asterix/lang/common/struct/VarIdentifier.java
@@ -21,10 +21,8 @@
 import java.util.Objects;
 
 public final class VarIdentifier extends Identifier {
-    private int id = 0;
 
-    public VarIdentifier() {
-    }
+    private int id;
 
     public VarIdentifier(VarIdentifier v) {
         this(v.getValue(), v.getId());
@@ -35,7 +33,7 @@
     }
 
     public VarIdentifier(String value, int id) {
-        this.value = value;
+        super(value);
         this.id = id;
     }
 
@@ -48,11 +46,6 @@
     }
 
     @Override
-    public VarIdentifier clone() {
-        return new VarIdentifier(value, id);
-    }
-
-    @Override
     public int hashCode() {
         return Objects.hash(value);
     }
diff --git a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/util/ExpressionToVariableUtil.java b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/util/ExpressionToVariableUtil.java
index d8534be..21ae883 100644
--- a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/util/ExpressionToVariableUtil.java
+++ b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/util/ExpressionToVariableUtil.java
@@ -96,8 +96,7 @@
         try {
             String varName = getGeneratedIdentifier(expr);
             VarIdentifier var = new VarIdentifier(varName);
-            VariableExpr varExpr = new VariableExpr();
-            varExpr.setVar(var);
+            VariableExpr varExpr = new VariableExpr(var);
             varExpr.setSourceLocation(expr.getSourceLocation());
             return varExpr;
         } catch (ParseException e) {
diff --git a/asterixdb/asterix-lang-sqlpp/src/main/javacc/SQLPP.jj b/asterixdb/asterix-lang-sqlpp/src/main/javacc/SQLPP.jj
index 60cdf2e..e0ad033 100644
--- a/asterixdb/asterix-lang-sqlpp/src/main/javacc/SQLPP.jj
+++ b/asterixdb/asterix-lang-sqlpp/src/main/javacc/SQLPP.jj
@@ -181,6 +181,7 @@
 import org.apache.asterix.lang.sqlpp.util.FunctionMapUtil;
 import org.apache.asterix.lang.sqlpp.util.SqlppVariableUtil;
 import org.apache.asterix.om.functions.BuiltinFunctions;
+import org.apache.asterix.om.types.BuiltinType;
 import org.apache.commons.lang3.ArrayUtils;
 import org.apache.commons.lang3.StringUtils;
 import org.apache.hyracks.algebricks.common.utils.Pair;
@@ -216,6 +217,8 @@
     private static final String TIES = "TIES";
     private static final String UNBOUNDED = "UNBOUNDED";
 
+    private static final String INT_TYPE_NAME = "int";
+
     // error configuration
     protected static final boolean REPORT_EXPECTED_TOKENS = false;
 
@@ -1644,8 +1647,8 @@
 {
   id = QualifiedName()
   {
-    if (id.first == null && id.second.getValue().equalsIgnoreCase("int")) {
-      id.second.setValue("int64");
+    if (id.first == null && id.second.getValue().equalsIgnoreCase(INT_TYPE_NAME)) {
+      id.second = new Identifier(BuiltinType.AINT64.getTypeName());
     }
 
     TypeReferenceExpression typeRef = new TypeReferenceExpression(id);
@@ -1727,8 +1730,8 @@
         result.function  = third;
       }
 
-      if (result.function.equalsIgnoreCase("int")) {
-            result.function = "int64";
+      if (result.function.equalsIgnoreCase(INT_TYPE_NAME)) {
+         result.function = BuiltinType.AINT64.getTypeName();
       }
       return result;
     }
@@ -2564,7 +2567,6 @@
 
 VariableExpr VariableRef() throws ParseException:
 {
-    VarIdentifier var = new VarIdentifier();
     String id = null;
 }
 {
@@ -2576,13 +2578,12 @@
        throw new SqlppParseException(getSourceLocation(token),
         "Inside limit clauses, it is disallowed to reference a variable having the same name as any variable bound in the same scope as the limit clause.");
      }
-     VariableExpr varExp = new VariableExpr();
+     VariableExpr varExp;
      if (ident != null) { // exist such ident
-       varExp.setVar((VarIdentifier)ident);
+       varExp = new VariableExpr((VarIdentifier)ident);
      } else {
-       varExp.setVar(var);
+       varExp = new VariableExpr(new VarIdentifier(id));
        varExp.setIsNewVar(false);
-       var.setValue(id);
      }
      return addSourceLocation(varExp, token);
     }
@@ -2590,7 +2591,6 @@
 
 VariableExpr Variable() throws ParseException:
 {
-    VarIdentifier var = new VarIdentifier();
     String id = null;
 }
 {
@@ -2598,12 +2598,10 @@
     {
      id = SqlppVariableUtil.toInternalVariableName(id); // prefix user-defined variables with "$".
      Identifier ident = lookupSymbol(id);
-     VariableExpr varExp = new VariableExpr();
-     if(ident != null) { // exist such ident
+     VariableExpr varExp = new VariableExpr(new VarIdentifier(id));
+     if (ident != null) { // exist such ident
        varExp.setIsNewVar(false);
      }
-     varExp.setVar(var);
-     var.setValue(id);
      return addSourceLocation(varExp, token);
     }
 }