diff options
Diffstat (limited to 'lib/sqlalchemy')
| -rw-r--r-- | lib/sqlalchemy/engine/result.py | 11 | ||||
| -rw-r--r-- | lib/sqlalchemy/orm/context.py | 42 | ||||
| -rw-r--r-- | lib/sqlalchemy/orm/session.py | 18 |
3 files changed, 49 insertions, 22 deletions
diff --git a/lib/sqlalchemy/engine/result.py b/lib/sqlalchemy/engine/result.py index 60474c0ed..3c2e682be 100644 --- a/lib/sqlalchemy/engine/result.py +++ b/lib/sqlalchemy/engine/result.py @@ -1054,6 +1054,17 @@ class Result(_WithKeys, ResultInternal): column of the first row, use the :meth:`.Result.scalar` method, or combine :meth:`.Result.scalars` and :meth:`.Result.first`. + Additionally, in contrast to the behavior of the legacy ORM + :meth:`_orm.Query.first` method, **no limit is applied** to the + SQL query which was invoked to produce this :class:`_engine.Result`; + for a DBAPI driver that buffers results in memory before yielding + rows, all rows will be sent to the Python process and all but + the first row will be discarded. + + .. seealso:: + + :ref:`migration_20_unify_select` + :return: a :class:`.Row` object, or None if no rows remain. diff --git a/lib/sqlalchemy/orm/context.py b/lib/sqlalchemy/orm/context.py index 83b6586cc..9318bb163 100644 --- a/lib/sqlalchemy/orm/context.py +++ b/lib/sqlalchemy/orm/context.py @@ -417,7 +417,10 @@ class ORMFromStatementCompileState(ORMCompileState): ) _QueryEntity.to_compile_state( - self, statement_container._raw_columns, self._entities + self, + statement_container._raw_columns, + self._entities, + is_current_entities=True, ) self.current_path = statement_container._compile_options._current_path @@ -590,6 +593,7 @@ class ORMSelectCompileState(ORMCompileState, SelectState): self, memoized_entities._raw_columns, [], + is_current_entities=False, ) for memoized_entities in ( select_statement._memoized_select_entities @@ -597,7 +601,10 @@ class ORMSelectCompileState(ORMCompileState, SelectState): } _QueryEntity.to_compile_state( - self, select_statement._raw_columns, self._entities + self, + select_statement._raw_columns, + self._entities, + is_current_entities=True, ) self.current_path = select_statement._compile_options._current_path @@ -839,7 +846,9 @@ class ORMSelectCompileState(ORMCompileState, SelectState): # entities will also set up polymorphic adapters for mappers # that have with_polymorphic configured - _QueryEntity.to_compile_state(self, query._raw_columns, self._entities) + _QueryEntity.to_compile_state( + self, query._raw_columns, self._entities, is_current_entities=True + ) return self @classmethod @@ -2278,13 +2287,18 @@ class _QueryEntity(object): use_id_for_hash = False @classmethod - def to_compile_state(cls, compile_state, entities, entities_collection): + def to_compile_state( + cls, compile_state, entities, entities_collection, is_current_entities + ): for idx, entity in enumerate(entities): if entity._is_lambda_element: if entity._is_sequence: cls.to_compile_state( - compile_state, entity._resolved, entities_collection + compile_state, + entity._resolved, + entities_collection, + is_current_entities, ) continue else: @@ -2294,7 +2308,10 @@ class _QueryEntity(object): if entity.is_selectable: if "parententity" in entity._annotations: _MapperEntity( - compile_state, entity, entities_collection + compile_state, + entity, + entities_collection, + is_current_entities, ) else: _ColumnEntity._for_columns( @@ -2343,12 +2360,15 @@ class _MapperEntity(_QueryEntity): "_polymorphic_discriminator", ) - def __init__(self, compile_state, entity, entities_collection): + def __init__( + self, compile_state, entity, entities_collection, is_current_entities + ): entities_collection.append(self) - if compile_state._primary_entity is None: - compile_state._primary_entity = self - compile_state._has_mapper_entities = True - compile_state._has_orm_entities = True + if is_current_entities: + if compile_state._primary_entity is None: + compile_state._primary_entity = self + compile_state._has_mapper_entities = True + compile_state._has_orm_entities = True entity = entity._annotations["parententity"] entity._post_inspect diff --git a/lib/sqlalchemy/orm/session.py b/lib/sqlalchemy/orm/session.py index 8302f70d6..fdef99370 100644 --- a/lib/sqlalchemy/orm/session.py +++ b/lib/sqlalchemy/orm/session.py @@ -1049,17 +1049,13 @@ class Session(_SessionClassMethods): :param enable_baked_queries: defaults to ``True``. A flag consumed by the :mod:`sqlalchemy.ext.baked` extension to determine if "baked queries" should be cached, as is the normal operation - of this extension. When set to ``False``, all caching is disabled, - including baked queries defined by the calling application as - well as those used internally. Setting this flag to ``False`` - can significantly reduce memory use, however will also degrade - performance for those areas that make use of baked queries - (such as relationship loaders). Additionally, baked query - logic in the calling application or potentially within the ORM - that may be malfunctioning due to cache key collisions or similar - can be flagged by observing if this flag resolves the issue. - - .. versionadded:: 1.2 + of this extension. When set to ``False``, caching as used by + this particular extension is disabled. + + .. versionchanged:: 1.4 The ``sqlalchemy.ext.baked`` extension is + legacy and is not used by any of SQLAlchemy's internals. This + flag therefore only affects applications that are making explicit + use of this extension within their own code. :param expire_on_commit: Defaults to ``True``. When ``True``, all instances will be fully expired after each :meth:`~.commit`, |