Bug fix, count(distinct field) should translate to cardinality aggreg…

src/main/java/com/amazon/opendistroforelasticsearch/sql/query/maker/AggMaker.java

@@ -15,6 +15,7 @@
 
 package com.amazon.opendistroforelasticsearch.sql.query.maker;
 
+import com.alibaba.druid.sql.ast.expr.SQLAggregateOption;
 import com.amazon.opendistroforelasticsearch.sql.domain.Condition;
 import com.amazon.opendistroforelasticsearch.sql.domain.Field;
 import com.amazon.opendistroforelasticsearch.sql.domain.KVValue;
@@ -697,7 +698,7 @@ private RangeAggregationBuilder rangeBuilder(MethodField field) {
     private ValuesSourceAggregationBuilder makeCountAgg(MethodField field) {
 
         // Cardinality is approximate DISTINCT.
-        if ("DISTINCT".equals(field.getOption())) {
+        if (SQLAggregateOption.DISTINCT.equals(field.getOption())) {
 
             if (field.getParams().size() == 1) {
                 return AggregationBuilders.cardinality(field.getAlias()).field(field.getParams().get(0).value

src/main/java/com/amazon/opendistroforelasticsearch/sql/query/planner/converter/SQLAggregationParser.java

@@ -17,6 +17,7 @@
 
 import com.alibaba.druid.sql.ast.SQLExpr;
 import com.alibaba.druid.sql.ast.expr.SQLAggregateExpr;
+import com.alibaba.druid.sql.ast.expr.SQLAggregateOption;
 import com.alibaba.druid.sql.ast.expr.SQLCastExpr;
 import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
 import com.alibaba.druid.sql.ast.expr.SQLMethodInvokeExpr;
@@ -259,8 +260,12 @@ public AggregationExpr(SQLAggregateExpr expr) {
         public static String nameOfExpr(SQLExpr expr) {
             String exprName = expr.toString().toLowerCase();
             if (expr instanceof SQLAggregateExpr) {
-                exprName = String.format("%s(%s)", ((SQLAggregateExpr) expr).getMethodName(),
-                                         ((SQLAggregateExpr) expr).getArguments().get(0));
+                SQLAggregateExpr aggExpr = (SQLAggregateExpr) expr;
+                SQLAggregateOption option = aggExpr.getOption();
+                exprName = option == null
+                        ? String.format("%s(%s)", aggExpr.getMethodName(), aggExpr.getArguments().get(0))
+                        : String.format("%s(%s %s)", aggExpr.getMethodName(), option.name(),
+                            aggExpr.getArguments().get(0));
             } else if (expr instanceof SQLMethodInvokeExpr) {
                 exprName = String.format("%s(%s)", ((SQLMethodInvokeExpr) expr).getMethodName(),
                         nameOfExpr(((SQLMethodInvokeExpr) expr).getParameters().get(0)));

src/test/java/com/amazon/opendistroforelasticsearch/sql/esintgtest/AggregationIT.java

@@ -38,6 +38,10 @@
 import static com.amazon.opendistroforelasticsearch.sql.esintgtest.TestsConstants.TEST_INDEX_GAME_OF_THRONES;
 import static com.amazon.opendistroforelasticsearch.sql.esintgtest.TestsConstants.TEST_INDEX_NESTED_TYPE;
 import static com.amazon.opendistroforelasticsearch.sql.esintgtest.TestsConstants.TEST_INDEX_ONLINE;
+import static com.amazon.opendistroforelasticsearch.sql.util.MatcherUtils.rows;
+import static com.amazon.opendistroforelasticsearch.sql.util.MatcherUtils.schema;
+import static com.amazon.opendistroforelasticsearch.sql.util.MatcherUtils.verifyDataRows;
+import static com.amazon.opendistroforelasticsearch.sql.util.MatcherUtils.verifySchema;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.greaterThanOrEqualTo;
@@ -64,6 +68,14 @@ public void countTest() throws IOException {
         Assert.assertThat(getIntAggregationValue(result, "COUNT(*)", "value"), equalTo(1000));
     }
 
+    @Test
+    public void countDistinctTest() {
+        JSONObject response = executeJdbcRequest(String.format("SELECT COUNT(distinct gender) FROM %s", TEST_INDEX_ACCOUNT));
+
+        verifySchema(response, schema("COUNT(DISTINCT gender)", null, "integer"));
+        verifyDataRows(response, rows(2));
+    }
+
     @Test
     public void countWithDocsHintTest() throws Exception {
 
@@ -1238,4 +1250,8 @@ private double getDoubleAggregationValue(final JSONObject queryResult, final Str
 
         return targetField.getDouble(subFieldName);
     }
+
+    private JSONObject executeJdbcRequest(String query) {
+        return new JSONObject(executeQuery(query, "jdbc"));
+    }
 }

src/test/java/com/amazon/opendistroforelasticsearch/sql/unittest/planner/converter/SQLAggregationParserTest.java

@@ -263,6 +263,20 @@ public void noGroupKeyInSelectShouldPass() {
                 columnNode("avg(age)", null, ExpressionFactory.ref("avg_0"))));
     }
 
+    @Test
+    public void aggWithDistinctShouldPass() {
+        String sql = "SELECT count(distinct gender) FROM t GROUP BY age";
+        SQLAggregationParser parser = new SQLAggregationParser(new ColumnTypeProvider());
+        parser.parse(mYSqlSelectQueryBlock(sql));
+        List<SQLSelectItem> sqlSelectItems = parser.selectItemList();
+        List<ColumnNode> columnNodes = parser.getColumnNodes();
+
+        assertThat(sqlSelectItems, containsInAnyOrder(
+                agg("count", "gender", "count_0")));
+        assertThat(columnNodes, containsInAnyOrder(
+                columnNode("count(distinct gender)", null, ExpressionFactory.ref("count_0"))));
+    }
+
     /**
      * TermQueryExplainIT.testNestedSingleGroupBy
      */