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Fixed #30375 -- Added FOR NO KEY UPDATE support to QuerySet.select_for_update() on PostgreSQL.

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This commit is contained in:
Manuel Weitzman
2020-05-10 12:25:06 -04:00
committed by Mariusz Felisiak
parent 0e893248b2
commit a4e6030904
10 changed files with 57 additions and 9 deletions
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1
django/db/backends/base/features.py
View File

@@ -38,6 +38,7 @@ class BaseDatabaseFeatures:
has_select_for_update_nowait = False
has_select_for_update_skip_locked = False
has_select_for_update_of = False
has_select_for_no_key_update = False
# Does the database's SELECT FOR UPDATE OF syntax require a column rather
# than a table?
select_for_update_of_column = False

5
django/db/backends/base/operations.py
View File

@@ -207,11 +207,12 @@ class BaseDatabaseOperations:
"""
return []
def for_update_sql(self, nowait=False, skip_locked=False, of=()):
def for_update_sql(self, nowait=False, skip_locked=False, of=(), no_key=False):
"""
Return the FOR UPDATE SQL clause to lock rows for an update operation.
"""
return 'FOR UPDATE%s%s%s' % (
return 'FOR%s UPDATE%s%s%s' % (
' NO KEY' if no_key else '',
' OF %s' % ', '.join(of) if of else '',
' NOWAIT' if nowait else '',
' SKIP LOCKED' if skip_locked else '',

1
django/db/backends/postgresql/features.py
View File

@@ -18,6 +18,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
has_select_for_update_nowait = True
has_select_for_update_of = True
has_select_for_update_skip_locked = True
has_select_for_no_key_update = True
can_release_savepoints = True
supports_tablespaces = True
supports_transactions = True

3
django/db/models/query.py
View File

@@ -1018,7 +1018,7 @@ class QuerySet:
return self
return self._combinator_query('difference', *other_qs)
def select_for_update(self, nowait=False, skip_locked=False, of=()):
def select_for_update(self, nowait=False, skip_locked=False, of=(), no_key=False):
"""
Return a new QuerySet instance that will select objects with a
FOR UPDATE lock.
@@ -1031,6 +1031,7 @@ class QuerySet:
obj.query.select_for_update_nowait = nowait
obj.query.select_for_update_skip_locked = skip_locked
obj.query.select_for_update_of = of
obj.query.select_for_no_key_update = no_key
return obj
def select_related(self, *fields):

13
django/db/models/sql/compiler.py
View File

@@ -546,19 +546,26 @@ class SQLCompiler:
nowait = self.query.select_for_update_nowait
skip_locked = self.query.select_for_update_skip_locked
of = self.query.select_for_update_of
# If it's a NOWAIT/SKIP LOCKED/OF query but the backend
# doesn't support it, raise NotSupportedError to prevent a
# possible deadlock.
no_key = self.query.select_for_no_key_update
# If it's a NOWAIT/SKIP LOCKED/OF/NO KEY query but the
# backend doesn't support it, raise NotSupportedError to
# prevent a possible deadlock.
if nowait and not self.connection.features.has_select_for_update_nowait:
raise NotSupportedError('NOWAIT is not supported on this database backend.')
elif skip_locked and not self.connection.features.has_select_for_update_skip_locked:
raise NotSupportedError('SKIP LOCKED is not supported on this database backend.')
elif of and not self.connection.features.has_select_for_update_of:
raise NotSupportedError('FOR UPDATE OF is not supported on this database backend.')
elif no_key and not self.connection.features.has_select_for_no_key_update:
raise NotSupportedError(
'FOR NO KEY UPDATE is not supported on this '
'database backend.'
)
for_update_part = self.connection.ops.for_update_sql(
nowait=nowait,
skip_locked=skip_locked,
of=self.get_select_for_update_of_arguments(),
no_key=no_key,
)
if for_update_part and self.connection.features.for_update_after_from:

1
django/db/models/sql/query.py
View File

@@ -189,6 +189,7 @@ class Query(BaseExpression):
self.select_for_update_nowait = False
self.select_for_update_skip_locked = False
self.select_for_update_of = ()
self.select_for_no_key_update = False
self.select_related = False
# Arbitrary limit for select_related to prevents infinite recursion.