Use AggregateDataCollecting instead of AggregateDataDefault for distinct aggregates

h2/src/main/org/h2/expression/aggregate/Aggregate.java

@@ -12,6 +12,7 @@ import java.util.HashMap;
 import org.h2.api.ErrorCode;
 import org.h2.command.dml.Select;
 import org.h2.command.dml.SelectOrderBy;
+import org.h2.engine.Database;
 import org.h2.engine.Session;
 import org.h2.expression.Expression;
 import org.h2.expression.ExpressionColumn;
@@ -417,12 +418,30 @@ public class Aggregate extends AbstractAggregate {
             data = (AggregateData) createAggregateData();
         }
         switch (type) {
-        case COUNT: {
-            if (!distinct) {
-                return data.getValue(session.getDatabase(), dataType, distinct);
-            }
+        case COUNT:
+            if (distinct) {
                 return ValueLong.get(((AggregateDataCollecting) data).getCount());
             }
+            break;
+        case SUM:
+        case AVG:
+        case STDDEV_POP:
+        case STDDEV_SAMP:
+        case VAR_POP:
+        case VAR_SAMP:
+            if (distinct) {
+                AggregateDataCollecting c = ((AggregateDataCollecting) data);
+                if (c.getCount() == 0) {
+                    return ValueNull.INSTANCE;
+                }
+                AggregateDataDefault d = new AggregateDataDefault(type);
+                Database db = session.getDatabase();
+                for (Value v : c) {
+                    d.add(db, dataType, false, v);
+                }
+                return d.getValue(db, dataType, false);
+            }
+            break;
         case GROUP_CONCAT: {
             Value[] array = ((AggregateDataCollecting) data).getArray();
             if (array == null) {
@@ -479,8 +498,9 @@ public class Aggregate extends AbstractAggregate {
             }
             //$FALL-THROUGH$
         default:
-            return data.getValue(session.getDatabase(), dataType, distinct);
+            // Avoid compiler warning
         }
+        return data.getValue(session.getDatabase(), dataType, distinct);
     }
 
     @Override

h2/src/main/org/h2/expression/aggregate/AggregateData.java

@@ -7,6 +7,7 @@ package org.h2.expression.aggregate;
 
 import org.h2.engine.Database;
 import org.h2.expression.aggregate.Aggregate.AggregateType;
+import org.h2.message.DbException;
 import org.h2.value.Value;
 
 /**
@@ -23,12 +24,6 @@ abstract class AggregateData {
      */
     static AggregateData create(AggregateType aggregateType, boolean distinct) {
         switch (aggregateType) {
-        case SELECTIVITY:
-            return new AggregateDataSelectivity();
-        case GROUP_CONCAT:
-        case ARRAY_AGG:
-        case MEDIAN:
-            break;
         case COUNT_ALL:
             return new AggregateDataCountAll();
         case COUNT:
@@ -36,6 +31,29 @@ abstract class AggregateData {
                 return new AggregateDataCount();
             }
             break;
+        case GROUP_CONCAT:
+        case ARRAY_AGG:
+        case MEDIAN:
+            break;
+        case MIN:
+        case MAX:
+        case BIT_OR:
+        case BIT_AND:
+        case BOOL_OR:
+        case BOOL_AND:
+            return new AggregateDataDefault(aggregateType);
+        case SUM:
+        case AVG:
+        case STDDEV_POP:
+        case STDDEV_SAMP:
+        case VAR_POP:
+        case VAR_SAMP:
+            if (!distinct) {
+                return new AggregateDataDefault(aggregateType);
+            }
+            break;
+        case SELECTIVITY:
+            return new AggregateDataSelectivity();
         case HISTOGRAM:
             return new AggregateDataHistogram();
         case MODE:
@@ -43,7 +61,7 @@ abstract class AggregateData {
         case ENVELOPE:
             return new AggregateDataEnvelope();
         default:
-            return new AggregateDataDefault(aggregateType);
+            throw DbException.throwInternalError("type=" + aggregateType);
         }
         return new AggregateDataCollecting();
     }

h2/src/main/org/h2/expression/aggregate/AggregateDataCollecting.java

@@ -7,7 +7,9 @@ package org.h2.expression.aggregate;
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.HashSet;
+import java.util.Iterator;
 
 import org.h2.engine.Database;
 import org.h2.value.Value;
@@ -23,7 +25,8 @@ import org.h2.value.ValueNull;
  * class instead.
  * </p>
  */
-class AggregateDataCollecting extends AggregateData {
+class AggregateDataCollecting extends AggregateData implements Iterable<Value> {
+
     Collection<Value> values;
 
     @Override
@@ -64,4 +67,10 @@ class AggregateDataCollecting extends AggregateData {
         }
         return values.toArray(new Value[0]);
     }
+
+    @Override
+    public Iterator<Value> iterator() {
+        return values != null ? values.iterator() : Collections.<Value>emptyIterator();
+    }
+
 }

h2/src/main/org/h2/expression/aggregate/AggregateDataDefault.java

@@ -8,7 +8,6 @@ package org.h2.expression.aggregate;
 import org.h2.engine.Database;
 import org.h2.expression.aggregate.Aggregate.AggregateType;
 import org.h2.message.DbException;
-import org.h2.util.ValueHashMap;
 import org.h2.value.DataType;
 import org.h2.value.Value;
 import org.h2.value.ValueBoolean;
@@ -20,9 +19,9 @@ import org.h2.value.ValueNull;
  * Data stored while calculating an aggregate.
  */
 class AggregateDataDefault extends AggregateData {
+
     private final AggregateType aggregateType;
     private long count;
-    private ValueHashMap<AggregateDataDefault> distinctValues;
     private Value value;
     private double m2, mean;
 
@@ -39,13 +38,6 @@ class AggregateDataDefault extends AggregateData {
             return;
         }
         count++;
-        if (distinct) {
-            if (distinctValues == null) {
-                distinctValues = ValueHashMap.newInstance();
-            }
-            distinctValues.put(v, this);
-            return;
-        }
         switch (aggregateType) {
         case SUM:
             if (value == null) {
@@ -128,9 +120,6 @@ class AggregateDataDefault extends AggregateData {
 
     @Override
     Value getValue(Database database, int dataType, boolean distinct) {
-        if (distinct) {
-            return getDistinct(database, dataType);
-        }
         Value v = null;
         switch (aggregateType) {
         case SUM:
@@ -191,15 +180,4 @@ class AggregateDataDefault extends AggregateData {
         return a;
     }
 
-    private Value getDistinct(Database database, int dataType) {
-        if (distinctValues == null) {
-            return ValueNull.INSTANCE;
-        }
-        AggregateDataDefault d = new AggregateDataDefault(aggregateType);
-        for (Value v : distinctValues.keys()) {
-            d.add(database, dataType, false, v);
-        }
-        return d.getValue(database, dataType, false);
-    }
-
 }