consider truediv as truediv; support floordiv operator

Implemented full support for "truediv" and "floordiv" using the
"/" and "//" operators.  A "truediv" operation between two expressions
using :class:`_types.Integer` now considers the result to be
:class:`_types.Numeric`, and the dialect-level compilation will cast
the right operand to a numeric type on a dialect-specific basis to ensure
truediv is achieved.  For floordiv, conversion is also added for those
databases that don't already do floordiv by default (MySQL, Oracle) and
the ``FLOOR()`` function is rendered in this case, as well as for
cases where the right operand is not an integer (needed for PostgreSQL,
others).

The change resolves issues both with inconsistent behavior of the
division operator on different backends and also fixes an issue where
integer division on Oracle would fail to be able to fetch a result due
to inappropriate outputtypehandlers.

Fixes: #4926
Change-Id: Id54cc018c1fb7a49dd3ce1216d68d40f43fe2659

1 files changed, 14 insertions, 4 deletions

diff --git a/lib/sqlalchemy/dialects/sqlite/pysqlite.py b/lib/sqlalchemy/dialects/sqlite/pysqlite.py
index 944d714a3..77c9ebce7 100644
--- a/lib/sqlalchemy/dialects/sqlite/pysqlite.py
+++ b/lib/sqlalchemy/dialects/sqlite/pysqlite.py
@@ -402,6 +402,7 @@ by adding the desired locking mode to our ``"BEGIN"``::
 
 """  # noqa
 
+import math
 import os
 import re
 
@@ -505,14 +506,23 @@ class SQLiteDialect_pysqlite(SQLiteDialect):
                 return None
             return re.search(a, b) is not None
 
+        create_func_kw = {"deterministic": True} if util.py38 else {}
+
         def set_regexp(dbapi_connection):
             dbapi_connection.create_function(
-                "regexp",
-                2,
-                regexp,
+                "regexp", 2, regexp, **create_func_kw
+            )
+
+        def floor_func(dbapi_connection):
+            # NOTE: floor is optionally present in sqlite 3.35+ , however
+            # as it is normally non-present we deliver floor() unconditionally
+            # for now.
+            # https://www.sqlite.org/lang_mathfunc.html
+            dbapi_connection.create_function(
+                "floor", 1, math.floor, **create_func_kw
             )
 
-        fns = [set_regexp]
+        fns = [set_regexp, floor_func]
 
         def connect(conn):
             for fn in fns: