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Fixed #31649 -- Added support for covering exclusion constraints on PostgreSQL 12+.

This commit is contained in:
Hannes Ljungberg 2020-06-11 21:05:38 +02:00 committed by Mariusz Felisiak
parent db8268bce6
commit e0cdd0fcf5
4 changed files with 175 additions and 7 deletions
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31
django/contrib/postgres/constraints.py
View File

@ -1,3 +1,4 @@
from django.db import NotSupportedError
from django.db.backends.ddl_references import Statement, Table
from django.db.models import Deferrable, F, Q
from django.db.models.constraints import BaseConstraint
@ -7,11 +8,11 @@ __all__ = ['ExclusionConstraint']
class ExclusionConstraint(BaseConstraint):
template = 'CONSTRAINT %(name)s EXCLUDE USING %(index_type)s (%(expressions)s)%(where)s%(deferrable)s'
template = 'CONSTRAINT %(name)s EXCLUDE USING %(index_type)s (%(expressions)s)%(include)s%(where)s%(deferrable)s'
def __init__(
self, *, name, expressions, index_type=None, condition=None,
deferrable=None,
deferrable=None, include=None,
):
if index_type and index_type.lower() not in {'gist', 'spgist'}:
raise ValueError(
@ -39,10 +40,19 @@ class ExclusionConstraint(BaseConstraint):
raise ValueError(
'ExclusionConstraint.deferrable must be a Deferrable instance.'
)
if not isinstance(include, (type(None), list, tuple)):
raise ValueError(
'ExclusionConstraint.include must be a list or tuple.'
)
if include and index_type and index_type.lower() != 'gist':
raise ValueError(
'Covering exclusion constraints only support GiST indexes.'
)
self.expressions = expressions
self.index_type = index_type or 'GIST'
self.condition = condition
self.deferrable = deferrable
self.include = tuple(include) if include else ()
super().__init__(name=name)
def _get_expression_sql(self, compiler, connection, query):
@ -67,15 +77,18 @@ class ExclusionConstraint(BaseConstraint):
compiler = query.get_compiler(connection=schema_editor.connection)
expressions = self._get_expression_sql(compiler, schema_editor.connection, query)
condition = self._get_condition_sql(compiler, schema_editor, query)
include = [model._meta.get_field(field_name).column for field_name in self.include]
return self.template % {
'name': schema_editor.quote_name(self.name),
'index_type': self.index_type,
'expressions': ', '.join(expressions),
'include': schema_editor._index_include_sql(model, include),
'where': ' WHERE (%s)' % condition if condition else '',
'deferrable': schema_editor._deferrable_constraint_sql(self.deferrable),
}
def create_sql(self, model, schema_editor):
self.check_supported(schema_editor)
return Statement(
'ALTER TABLE %(table)s ADD %(constraint)s',
table=Table(model._meta.db_table, schema_editor.quote_name),
@ -89,6 +102,12 @@ class ExclusionConstraint(BaseConstraint):
schema_editor.quote_name(self.name),
)
def check_supported(self, schema_editor):
if self.include and not schema_editor.connection.features.supports_covering_gist_indexes:
raise NotSupportedError(
'Covering exclusion constraints requires PostgreSQL 12+.'
)
def deconstruct(self):
path, args, kwargs = super().deconstruct()
kwargs['expressions'] = self.expressions
@ -98,6 +117,8 @@ class ExclusionConstraint(BaseConstraint):
kwargs['index_type'] = self.index_type
if self.deferrable:
kwargs['deferrable'] = self.deferrable
if self.include:
kwargs['include'] = self.include
return path, args, kwargs
def __eq__(self, other):
@ -107,15 +128,17 @@ class ExclusionConstraint(BaseConstraint):
self.index_type == other.index_type and
self.expressions == other.expressions and
self.condition == other.condition and
self.deferrable == other.deferrable
self.deferrable == other.deferrable and
self.include == other.include
)
return super().__eq__(other)
def __repr__(self):
return '<%s: index_type=%s, expressions=%s%s%s>' % (
return '<%s: index_type=%s, expressions=%s%s%s%s>' % (
self.__class__.__qualname__,
self.index_type,
self.expressions,
'' if self.condition is None else ', condition=%s' % self.condition,
'' if self.deferrable is None else ', deferrable=%s' % self.deferrable,
'' if not self.include else ', include=%s' % repr(self.include),
)

17
docs/ref/contrib/postgres/constraints.txt
View File

@ -12,7 +12,7 @@ PostgreSQL supports additional data integrity constraints available from the
``ExclusionConstraint``
=======================
.. class:: ExclusionConstraint(*, name, expressions, index_type=None, condition=None, deferrable=None)
.. class:: ExclusionConstraint(*, name, expressions, index_type=None, condition=None, deferrable=None, include=None)
Creates an exclusion constraint in the database. Internally, PostgreSQL
implements exclusion constraints using indexes. The default index type is
@ -106,6 +106,21 @@ enforced immediately after every command.
Deferred exclusion constraints may lead to a `performance penalty
<https://www.postgresql.org/docs/current/sql-createtable.html#id-1.9.3.85.9.4>`_.
``include``
-----------
.. attribute:: ExclusionConstraint.include
.. versionadded:: 3.2
A list or tuple of the names of the fields to be included in the covering
exclusion constraint as non-key columns. This allows index-only scans to be
used for queries that select only included fields
(:attr:`~ExclusionConstraint.include`) and filter only by indexed fields
(:attr:`~ExclusionConstraint.expressions`).
``include`` is supported only for GiST indexes on PostgreSQL 12+.
Examples
--------

3
docs/releases/3.2.txt
View File

@ -70,7 +70,8 @@ Minor features
:mod:`django.contrib.postgres`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* ...
* The new :attr:`.ExclusionConstraint.include` attribute allows creating
covering exclusion constraints on PostgreSQL 12+.
:mod:`django.contrib.redirects`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

131
tests/postgres_tests/test_constraints.py
View File

@ -1,8 +1,11 @@
import datetime
from unittest import mock
from django.db import IntegrityError, connection, transaction
from django.db import (
IntegrityError, NotSupportedError, connection, transaction,
)
from django.db.models import CheckConstraint, Deferrable, F, Func, Q
from django.test import skipUnlessDBFeature
from django.utils import timezone
from . import PostgreSQLTestCase
@ -146,6 +149,25 @@ class ExclusionConstraintTests(PostgreSQLTestCase):
deferrable=Deferrable.DEFERRED,
)
def test_invalid_include_type(self):
msg = 'ExclusionConstraint.include must be a list or tuple.'
with self.assertRaisesMessage(ValueError, msg):
ExclusionConstraint(
name='exclude_invalid_include',
expressions=[(F('datespan'), RangeOperators.OVERLAPS)],
include='invalid',
)
def test_invalid_include_index_type(self):
msg = 'Covering exclusion constraints only support GiST indexes.'
with self.assertRaisesMessage(ValueError, msg):
ExclusionConstraint(
name='exclude_invalid_index_type',
expressions=[(F('datespan'), RangeOperators.OVERLAPS)],
include=['cancelled'],
index_type='spgist',
)
def test_repr(self):
constraint = ExclusionConstraint(
name='exclude_overlapping',
@ -180,6 +202,16 @@ class ExclusionConstraintTests(PostgreSQLTestCase):
"<ExclusionConstraint: index_type=GIST, expressions=["
"(F(datespan), '-|-')], deferrable=Deferrable.IMMEDIATE>",
)
constraint = ExclusionConstraint(
name='exclude_overlapping',
expressions=[(F('datespan'), RangeOperators.ADJACENT_TO)],
include=['cancelled', 'room'],
)
self.assertEqual(
repr(constraint),
"<ExclusionConstraint: index_type=GIST, expressions=["
"(F(datespan), '-|-')], include=('cancelled', 'room')>",
)
def test_eq(self):
constraint_1 = ExclusionConstraint(
@ -218,6 +250,23 @@ class ExclusionConstraintTests(PostgreSQLTestCase):
],
deferrable=Deferrable.IMMEDIATE,
)
constraint_6 = ExclusionConstraint(
name='exclude_overlapping',
expressions=[
('datespan', RangeOperators.OVERLAPS),
('room', RangeOperators.EQUAL),
],
deferrable=Deferrable.IMMEDIATE,
include=['cancelled'],
)
constraint_7 = ExclusionConstraint(
name='exclude_overlapping',
expressions=[
('datespan', RangeOperators.OVERLAPS),
('room', RangeOperators.EQUAL),
],
include=['cancelled'],
)
self.assertEqual(constraint_1, constraint_1)
self.assertEqual(constraint_1, mock.ANY)
self.assertNotEqual(constraint_1, constraint_2)
@ -225,7 +274,9 @@ class ExclusionConstraintTests(PostgreSQLTestCase):
self.assertNotEqual(constraint_1, constraint_4)
self.assertNotEqual(constraint_2, constraint_3)
self.assertNotEqual(constraint_2, constraint_4)
self.assertNotEqual(constraint_2, constraint_7)
self.assertNotEqual(constraint_4, constraint_5)
self.assertNotEqual(constraint_5, constraint_6)
self.assertNotEqual(constraint_1, object())
def test_deconstruct(self):
@ -286,6 +337,21 @@ class ExclusionConstraintTests(PostgreSQLTestCase):
'deferrable': Deferrable.DEFERRED,
})
def test_deconstruct_include(self):
constraint = ExclusionConstraint(
name='exclude_overlapping',
expressions=[('datespan', RangeOperators.OVERLAPS)],
include=['cancelled', 'room'],
)
path, args, kwargs = constraint.deconstruct()
self.assertEqual(path, 'django.contrib.postgres.constraints.ExclusionConstraint')
self.assertEqual(args, ())
self.assertEqual(kwargs, {
'name': 'exclude_overlapping',
'expressions': [('datespan', RangeOperators.OVERLAPS)],
'include': ('cancelled', 'room'),
})
def _test_range_overlaps(self, constraint):
# Create exclusion constraint.
self.assertNotIn(constraint.name, self.get_constraints(HotelReservation._meta.db_table))
@ -417,3 +483,66 @@ class ExclusionConstraintTests(PostgreSQLTestCase):
adjacent_range.delete()
RangesModel.objects.create(ints=(10, 19))
RangesModel.objects.create(ints=(51, 60))
@skipUnlessDBFeature('supports_covering_gist_indexes')
def test_range_adjacent_include(self):
constraint_name = 'ints_adjacent_include'
self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
constraint = ExclusionConstraint(
name=constraint_name,
expressions=[('ints', RangeOperators.ADJACENT_TO)],
include=['decimals', 'ints'],
index_type='gist',
)
with connection.schema_editor() as editor:
editor.add_constraint(RangesModel, constraint)
self.assertIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
RangesModel.objects.create(ints=(20, 50))
with self.assertRaises(IntegrityError), transaction.atomic():
RangesModel.objects.create(ints=(10, 20))
RangesModel.objects.create(ints=(10, 19))
RangesModel.objects.create(ints=(51, 60))
@skipUnlessDBFeature('supports_covering_gist_indexes')
def test_range_adjacent_include_condition(self):
constraint_name = 'ints_adjacent_include_condition'
self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
constraint = ExclusionConstraint(
name=constraint_name,
expressions=[('ints', RangeOperators.ADJACENT_TO)],
include=['decimals'],
condition=Q(id__gte=100),
)
with connection.schema_editor() as editor:
editor.add_constraint(RangesModel, constraint)
self.assertIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
@skipUnlessDBFeature('supports_covering_gist_indexes')
def test_range_adjacent_include_deferrable(self):
constraint_name = 'ints_adjacent_include_deferrable'
self.assertNotIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
constraint = ExclusionConstraint(
name=constraint_name,
expressions=[('ints', RangeOperators.ADJACENT_TO)],
include=['decimals'],
deferrable=Deferrable.DEFERRED,
)
with connection.schema_editor() as editor:
editor.add_constraint(RangesModel, constraint)
self.assertIn(constraint_name, self.get_constraints(RangesModel._meta.db_table))
def test_include_not_supported(self):
constraint_name = 'ints_adjacent_include_not_supported'
constraint = ExclusionConstraint(
name=constraint_name,
expressions=[('ints', RangeOperators.ADJACENT_TO)],
include=['id'],
)
msg = 'Covering exclusion constraints requires PostgreSQL 12+.'
with connection.schema_editor() as editor:
with mock.patch(
'django.db.backends.postgresql.features.DatabaseFeatures.supports_covering_gist_indexes',
False,
):
with self.assertRaisesMessage(NotSupportedError, msg):
editor.add_constraint(RangesModel, constraint)