Fixed #24033 -- Use interval type on Oracle.

Use INTERVAL DAY(9) TO SECOND(6) for Durationfield on Oracle rather than
storing as a NUMBER(19) of microseconds.

There are issues with cx_Oracle which require some extra data
manipulation in the database backend when constructing queries, but it
handles the conversion back to timedelta objects cleanly.

Thanks to Shai for the review.

django/db/backends/__init__.py

@@ -580,6 +580,12 @@ class BaseDatabaseFeatures(object):
     # Is there a true datatype for timedeltas?
     has_native_duration_field = False
 
+    # Does the database driver support timedeltas as arguments?
+    # This is only relevant when there is a native duration field.
+    # Specifically, there is a bug with cx_Oracle:
+    # https://bitbucket.org/anthony_tuininga/cx_oracle/issue/7/
+    driver_supports_timedelta_args = False
+
     # Do time/datetime fields have microsecond precision?
     supports_microsecond_precision = True
 

django/db/backends/oracle/base.py

@@ -62,6 +62,7 @@ from django.db.backends.oracle.introspection import DatabaseIntrospection
 from django.db.backends.oracle.schema import DatabaseSchemaEditor
 from django.db.utils import InterfaceError
 from django.utils import six, timezone
+from django.utils.duration import duration_string
 from django.utils.encoding import force_bytes, force_text
 from django.utils.functional import cached_property
 
@@ -106,6 +107,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     supports_timezones = False
     has_zoneinfo_database = pytz is not None
     supports_bitwise_or = False
+    has_native_duration_field = True
     can_defer_constraint_checks = True
     supports_partially_nullable_unique_constraints = False
     truncates_names = True
@@ -212,9 +214,6 @@ WHEN (new.%(col_name)s IS NULL)
         return fmt % (days, hours, minutes, seconds, timedelta.microseconds,
                 day_precision), []
 
-    def format_for_duration_arithmetic(self, sql):
-        return "NUMTODSINTERVAL(%s / 1000000, 'SECOND')" % sql
-
     def date_trunc_sql(self, lookup_type, field_name):
         # http://docs.oracle.com/cd/B19306_01/server.102/b14200/functions230.htm#i1002084
         if lookup_type in ('year', 'month'):
@@ -796,6 +795,11 @@ class OracleParam(object):
                 param = timezone.make_aware(param, default_timezone)
             param = Oracle_datetime.from_datetime(param.astimezone(timezone.utc))
 
+        if isinstance(param, datetime.timedelta):
+            param = duration_string(param)
+            if ' ' not in param:
+                param = '0 ' + param
+
         string_size = 0
         # Oracle doesn't recognize True and False correctly in Python 3.
         # The conversion done below works both in 2 and 3.

django/db/backends/oracle/creation.py

@@ -29,7 +29,7 @@ class DatabaseCreation(BaseDatabaseCreation):
         'DateField': 'DATE',
         'DateTimeField': 'TIMESTAMP',
         'DecimalField': 'NUMBER(%(max_digits)s, %(decimal_places)s)',
-        'DurationField': 'NUMBER(19)',
+        'DurationField': 'INTERVAL DAY(9) TO SECOND(6)',
         'FileField': 'NVARCHAR2(%(max_length)s)',
         'FilePathField': 'NVARCHAR2(%(max_length)s)',
         'FloatField': 'DOUBLE PRECISION',

django/db/backends/postgresql_psycopg2/base.py

@@ -48,6 +48,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     can_return_id_from_insert = True
     has_real_datatype = True
     has_native_duration_field = True
+    driver_supports_timedelta_args = True
     can_defer_constraint_checks = True
     has_select_for_update = True
     has_select_for_update_nowait = True

django/db/models/expressions.py

@@ -488,7 +488,8 @@ class Value(ExpressionNode):
 
 class DurationValue(Value):
     def as_sql(self, compiler, connection):
-        if connection.features.has_native_duration_field:
+        if (connection.features.has_native_duration_field and
+                connection.features.driver_supports_timedelta_args):
             return super(DurationValue, self).as_sql(compiler, connection)
         return connection.ops.date_interval_sql(self.value)
 

django/db/models/fields/__init__.py

@@ -1577,7 +1577,8 @@ class DecimalField(Field):
 class DurationField(Field):
     """Stores timedelta objects.
 
-    Uses interval on postgres, bigint of microseconds on other databases.
+    Uses interval on postgres, INVERAL DAY TO SECOND on Oracle, and bigint of
+    microseconds on other databases.
     """
     empty_strings_allowed = False
     default_error_messages = {

docs/ref/models/fields.txt

@@ -551,7 +551,8 @@ The default form widget for this field is a :class:`~django.forms.TextInput`.
 
 A field for storing periods of time - modeled in Python by
 :class:`~python:datetime.timedelta`. When used on PostgreSQL, the data type
-used is an ``interval``, otherwise a ``bigint`` of microseconds is used.
+used is an ``interval`` and on Oracle the data type is ``INTERVAL DAY(9) TO
+SECOND(6)``. Otherwise a ``bigint`` of microseconds is used.
 
 .. note::
 

docs/releases/1.8.txt

@@ -60,9 +60,10 @@ New data types
 
 * Django now has a :class:`~django.db.models.DurationField` for storing periods
   of time - modeled in Python by :class:`~python:datetime.timedelta`. It is
-  stored in the native ``interval`` data type on PostgreSQL and as a ``bigint``
-  of microseconds on other backends. Date and time related arithmetic has also
-  been improved on all backends. There is a corresponding :class:`form field
+  stored in the native ``interval`` data type on PostgreSQL, as a ``INTERVAL
+  DAY(9) TO SECOND(6)`` on Oracle, and as a ``bigint`` of microseconds on other
+  backends. Date and time related arithmetic has also been improved on all
+  backends. There is a corresponding :class:`form field
   <django.forms.DurationField>`.
 
 Query Expressions