Support a query with multiple statments (unofficially)

Author: sonots

lib/vertica/query.rb

@@ -83,7 +83,8 @@ def handle_data_row(message)
   def handle_command_complete(message)
     if buffer_rows?
       @result = Vertica::Result.new(row_description: @row_description, rows: @buffer, tag: message.tag)
-      @row_description, @buffer = nil, nil
+      @row_description = nil
+      @buffer = []
     else
       @result = message.tag
     end

test/functional/functional_query_test.rb

@@ -81,6 +81,20 @@ def test_select_query_with_multibyte_column_names_results
     assert_equal 'ニ', r.row_description[1].name
   end
 
+  # Query with multiple statements is not officailly supported
+  def test_query_with_multiple_statements
+    # Results of only the last statement are obtained
+    r = @connection.query("SET SEARCH_PATH TO default; SELECT 1 as one; SELECT 2 as two")
+    assert_equal 1, r.size
+    assert_equal 1, r.row_description.length
+    assert_equal 'two', r.row_description[0].name
+
+    # Error of the former statement is raised
+    assert_raises(Vertica::Error::MissingColumn) do
+      @connection.query("SELECT missing FROM test_ruby_vertica_table; SELECT 1 FROM missing")
+    end
+  end
+
   def test_insert
     r = @connection.query("INSERT INTO test_ruby_vertica_table VALUES (2, 'stefanie')")
     assert_equal "INSERT", r.tag