Merge pull request #1480 from dumbunny/v2v3

Update sql_builder.AfterPrevValues.

py/vtdb/sql_builder.py

@@ -956,25 +956,30 @@ def build_update_value_sql(self, column_name):
     return clause, bind_vars
 
 
-class AfterPrevValues(BaseWhereExpr):
+class TupleCompare(BaseWhereExpr):
   """Create SQL for an after clause in a multi-dimensional scan.
 
-  Example: If reading values ordered by columns (x, y, z) starting at
+  Example: If reading values ordered by columns (x, y, z) starting after
   the point (3, 5, 7), build the SQL:
 
     "x = 3 AND (y = 5 AND z > 7 OR y > 5) OR x > 3".
+
+  NOTE: MySQL supports "(x, y, z) > (3, 5, 7)" to do the same thing,
+  but we have found that the optimizer frequently does not recognize
+  this as an indexed, range query. Surprisingly, it has a better chance
+  of efficiently using with the above inequality.
   """
 
-  def __init__(self, prev_value_pairs, asc=True, inclusive=False):
+  def __init__(self, starting_point, asc=True, inclusive=False):
     """Constructor.
 
     Args:
-      prev_value_pairs: Ordered list of (column, prev_value) pairs.
+      starting_point: Ordered list of (column, start_value) pairs.
         Example - [('x', 3), ('y', 5), ('z', 7)].
       asc: If True, scan forward.
       inclusive: If True, also include starting point.
     """
-    self.prev_value_pairs = prev_value_pairs
+    self.starting_point = starting_point
     self.asc = asc
     self.inclusive = inclusive
 
@@ -997,7 +1002,7 @@ def build_where_sql(self, column_name, counter):
     where_clause = None
     is_complex = False
     bind_vars = {}
-    for column, prev_value in reversed(self.prev_value_pairs):
+    for column, prev_value in reversed(self.starting_point):
       bind_name = choose_bind_name(column, counter)
       if isinstance(prev_value, (list, tuple, set)):
         raise ValueError(
@@ -1022,6 +1027,58 @@ def build_where_sql(self, column_name, counter):
     return where_clause, bind_vars
 
 
+class TupleGreater(TupleCompare):
+  """WHERE expr for tuple > values expr.
+
+  starting_point=[('x', 3), ('y', 5)] makes: '(x, y) > (3, 5)'.
+
+  See TupleCompare.
+  """
+
+  def __init__(self, starting_point):
+    super(TupleGreater, self).__init__(
+        starting_point, asc=True, inclusive=False)
+
+
+class TupleGreaterEqual(TupleCompare):
+  """WHERE expr for tuple >= values expr.
+
+  starting_point=[('x', 3), ('y', 5)] makes: '(x, y) >= (3, 5)'.
+
+  See TupleCompare.
+  """
+
+  def __init__(self, starting_point):
+    super(TupleGreaterEqual, self).__init__(
+        starting_point, asc=True, inclusive=True)
+
+
+class TupleLess(TupleCompare):
+  """WHERE expr for tuple < values expr.
+
+  starting_point=[('x', 3), ('y', 5)] makes: '(x, y) < (3, 5)'.
+
+  See TupleCompare.
+  """
+
+  def __init__(self, starting_point):
+    super(TupleLess, self).__init__(
+        starting_point, asc=False, inclusive=False)
+
+
+class TupleLessEqual(TupleCompare):
+  """WHERE expr for tuple <= values expr.
+
+  starting_point=[('x', 3), ('y', 5)] makes: '(x, y) <= (3, 5)'.
+
+  See TupleCompare.
+  """
+
+  def __init__(self, starting_point):
+    super(TupleLessEqual, self).__init__(
+        starting_point, asc=False, inclusive=True)
+
+
 def make_flags(flag_mask, value):
   if value:
     return Flags(flags_present=flag_mask)

test/sql_builder_test.py

@@ -556,24 +556,29 @@ def test_or_exprs(self):
         '(col_a = %(col_a_5)s))',
         dict(col_a_3=11, col_a_4=20, col_a_5=30))
 
-  def test_after_prev__values(self):
+  def test_tuple_compare(self):
     self._check_build_where_sql(
-        sql_builder.AfterPrevValues([('x', 3), ('y', 5), ('z', 7)]),
-        'x = %(x_5)s AND (y = %(y_4)s AND z > %(z_3)s OR y > %(y_4)s) '
-        'OR x > %(x_5)s',
+        sql_builder.TupleGreater([('x', 3), ('y', 5), ('z', 7)]),
+        'x = %(x_5)s AND '
+        '(y = %(y_4)s AND z > %(z_3)s OR y > %(y_4)s) OR x > %(x_5)s',
         dict(x_5=3, y_4=5, z_3=7),
         column_name=None)
     self._check_build_where_sql(
-        sql_builder.AfterPrevValues(
-            [('x', 3), ('y', 5), ('z', 7)], inclusive=True),
-        'x = %(x_5)s AND (y = %(y_4)s AND z >= %(z_3)s OR y > %(y_4)s) '
-        'OR x > %(x_5)s',
+        sql_builder.TupleGreaterEqual([('x', 3), ('y', 5), ('z', 7)]),
+        'x = %(x_5)s AND '
+        '(y = %(y_4)s AND z >= %(z_3)s OR y > %(y_4)s) OR x > %(x_5)s',
         dict(x_5=3, y_4=5, z_3=7),
         column_name=None)
     self._check_build_where_sql(
-        sql_builder.AfterPrevValues([('x', 3), ('y', 5), ('z', 7)], asc=False),
-        'x = %(x_5)s AND (y = %(y_4)s AND z < %(z_3)s OR y < %(y_4)s) '
-        'OR x < %(x_5)s',
+        sql_builder.TupleLess([('x', 3), ('y', 5), ('z', 7)]),
+        'x = %(x_5)s AND '
+        '(y = %(y_4)s AND z < %(z_3)s OR y < %(y_4)s) OR x < %(x_5)s',
+        dict(x_5=3, y_4=5, z_3=7),
+        column_name=None)
+    self._check_build_where_sql(
+        sql_builder.TupleLessEqual([('x', 3), ('y', 5), ('z', 7)]),
+        'x = %(x_5)s AND '
+        '(y = %(y_4)s AND z <= %(z_3)s OR y < %(y_4)s) OR x < %(x_5)s',
         dict(x_5=3, y_4=5, z_3=7),
         column_name=None)