If SQLITE_MAX_VARIABLE_NUMBER (default = 999) is changed at compile time
to be greater than SQLITE_MAX_COLUMN (default = 2000), which Debian does
by setting the former to 250000, Django raised an exception on queries
containing more than 2000 parameters when DEBUG = True.
The primary use case is to interact with a third-party database (not
primarily managed by Django) that doesn't support time zones and where
datetimes are stored in local time when USE_TZ is True.
Configuring a PostgreSQL database with the TIME_ZONE option while USE_TZ
is False used to result in silent data corruption. Now this is an error.
Refs #23820.
Fixed#19738.
Refs #17755. In order not to introduce a regression for raw queries,
parameters are passed through the connection.ops.value_to_db_* methods,
depending on their type.
Field.rel is now deprecated. Rel objects have now also remote_field
attribute. This means that self == self.remote_field.remote_field.
In addition, made the Rel objects a bit more like Field objects. Still,
marked ManyToManyFields as null=True.
Table alterations in SQLite require creating a new table and copying
data over from the old one. This change ensures that no Django model
ever exists with the temporary table name as its db_table attribute.
As suggested by Anssi. This has the slightly strange side effect of
passing the expression to Expression.convert_value has the expression
passed back to it, but it allows more complex patterns of expressions.
Refactored compiler SELECT, GROUP BY and ORDER BY generation.
While there, also refactored select_related() implementation
(get_cached_row() and get_klass_info() are now gone!).
Made get_db_converters() method work on expressions instead of
internal_type. This allows the backend converters to target
specific expressions if need be.
Added query.context, this can be used to set per-query state.
Also changed the signature of database converters. They now accept
context as an argument.
A field for storing periods of time - modeled in Python by timedelta. It
is stored in the native interval data type on PostgreSQL and as a bigint
of microseconds on other backends.
Also includes significant changes to the internals of time related maths
in expressions, including the removal of DateModifierNode.
Thanks to Tim and Josh in particular for reviews.