Return a blank ResultSet instead of null

Author: Paultagoras

jdbc-v2/src/main/java/com/clickhouse/jdbc/metadata/DatabaseMetaDataImpl.java

@@ -1065,7 +1065,14 @@ private static String getDataTypeInfoSql() {
 
     @Override
     public ResultSet getIndexInfo(String catalog, String schema, String table, boolean unique, boolean approximate) throws SQLException {
-        return null;
+        try {
+            String sql = "SELECT null AS TABLE_CAT, null AS TABLE_SCHEM, null AS TABLE_NAME, null AS NON_UNIQUE," +
+                    " null AS INDEX_QUALIFIER, null AS INDEX_NAME, null AS TYPE, null AS ORDINAL_POSITION, null AS COLUMN_NAME, null AS ASC_OR_DESC," +
+                    " null AS CARDINALITY, null AS PAGES, null AS FILTER_CONDITION LIMIT 0";
+            return connection.createStatement().executeQuery(sql);
+        } catch (Exception e) {
+            throw ExceptionUtils.toSqlState(e);
+        }
     }
 
     @Override

jdbc-v2/src/test/java/com/clickhouse/jdbc/metadata/DatabaseMetaDataTest.java

@@ -316,4 +316,14 @@ public void testGetDriverVersion() throws Exception {
             assertNotEquals(version, "unknown");
         }
     }
+
+
+    @Test(groups = { "integration" })
+    public void testGetIndexInfo() throws Exception {
+        try (Connection conn = getJdbcConnection()) {
+            DatabaseMetaData dbmd = conn.getMetaData();
+            ResultSet rs = dbmd.getIndexInfo(null, null, "numbers", false, false);
+            assertFalse(rs.next());
+        }
+    }
 }