Fixed #28926 -- Fixed loss of precision of big DurationField values on SQLite and MySQL.

4 files changed, 10 insertions, 5 deletions

diff --git a/django/db/backends/mysql/operations.py b/django/db/backends/mysql/operations.py
index 7c901d78d8..ad4c13652e 100644
--- a/django/db/backends/mysql/operations.py
+++ b/django/db/backends/mysql/operations.py
@@ -3,6 +3,7 @@ import uuid
 from django.conf import settings
 from django.db.backends.base.operations import BaseDatabaseOperations
 from django.utils import timezone
+from django.utils.duration import duration_microseconds
 from django.utils.encoding import force_text
 
 
@@ -105,7 +106,7 @@ class DatabaseOperations(BaseDatabaseOperations):
             return "TIME(%s)" % (field_name)
 
     def date_interval_sql(self, timedelta):
-        return "INTERVAL '%06f' SECOND_MICROSECOND" % timedelta.total_seconds()
+        return 'INTERVAL %s MICROSECOND' % duration_microseconds(timedelta)
 
     def format_for_duration_arithmetic(self, sql):
         return 'INTERVAL %s MICROSECOND' % sql
diff --git a/django/db/backends/sqlite3/base.py b/django/db/backends/sqlite3/base.py
index d15352dcc6..d3caa6d12a 100644
--- a/django/db/backends/sqlite3/base.py
+++ b/django/db/backends/sqlite3/base.py
@@ -17,6 +17,7 @@ from django.utils import timezone
 from django.utils.dateparse import (
     parse_date, parse_datetime, parse_duration, parse_time,
 )
+from django.utils.duration import duration_microseconds
 
 from .client import DatabaseClient                          # isort:skip
 from .creation import DatabaseCreation                      # isort:skip
@@ -471,7 +472,7 @@ def _sqlite_time_diff(lhs, rhs):
 def _sqlite_timestamp_diff(lhs, rhs):
     left = backend_utils.typecast_timestamp(lhs)
     right = backend_utils.typecast_timestamp(rhs)
-    return (left - right).total_seconds() * 1000000
+    return duration_microseconds(left - right)
 
 
 def _sqlite_regexp(re_pattern, re_string):
diff --git a/django/db/models/fields/__init__.py b/django/db/models/fields/__init__.py
index a67cf9b647..188b5bb907 100644
--- a/django/db/models/fields/__init__.py
+++ b/django/db/models/fields/__init__.py
@@ -24,7 +24,7 @@ from django.utils.datastructures import DictWrapper
 from django.utils.dateparse import (
     parse_date, parse_datetime, parse_duration, parse_time,
 )
-from django.utils.duration import duration_string
+from django.utils.duration import duration_microseconds, duration_string
 from django.utils.encoding import force_bytes, smart_text
 from django.utils.functional import Promise, cached_property
 from django.utils.ipv6 import clean_ipv6_address
@@ -1617,8 +1617,7 @@ class DurationField(Field):
             return value
         if value is None:
             return None
-        # Discard any fractional microseconds due to floating point arithmetic.
-        return round(value.total_seconds() * 1000000)
+        return duration_microseconds(value)
 
     def get_db_converters(self, connection):
         converters = []
diff --git a/django/utils/duration.py b/django/utils/duration.py
index 53322b51d2..466603d46c 100644
--- a/django/utils/duration.py
+++ b/django/utils/duration.py
@@ -38,3 +38,7 @@ def duration_iso_string(duration):
     days, hours, minutes, seconds, microseconds = _get_duration_components(duration)
     ms = '.{:06d}'.format(microseconds) if microseconds else ""
     return '{}P{}DT{:02d}H{:02d}M{:02d}{}S'.format(sign, days, hours, minutes, seconds, ms)
+
+
+def duration_microseconds(delta):
+    return (24 * 60 * 60 * delta.days + delta.seconds) * 1000000 + delta.microseconds