diff options
| -rw-r--r-- | CHANGES | 7 | ||||
| -rw-r--r-- | examples/sharding/attribute_shard.py | 3 | ||||
| -rw-r--r-- | lib/sqlalchemy/orm/session.py | 34 | ||||
| -rw-r--r-- | lib/sqlalchemy/orm/shard.py | 14 | ||||
| -rw-r--r-- | lib/sqlalchemy/orm/strategies.py | 5 | ||||
| -rw-r--r-- | test/orm/sharding/shard.py | 5 |
6 files changed, 46 insertions, 22 deletions
@@ -24,6 +24,13 @@ CHANGES - column defaults and onupdates, executing inline, will add parenthesis for subqueries and other parenthesis-requiring expressions +- fixes to ShardedSession to work with deferred columns [ticket:771]. + +- user-defined shard_chooser() function must accept "clause=None" + argument; this is the ClauseElement passed to session.execute(statement) + and can be used to determine correct shard id (since execute() doesn't + take an instance) + 0.4.0beta5 ---------- diff --git a/examples/sharding/attribute_shard.py b/examples/sharding/attribute_shard.py index 25da98872..0a9e992a3 100644 --- a/examples/sharding/attribute_shard.py +++ b/examples/sharding/attribute_shard.py @@ -22,6 +22,7 @@ from sqlalchemy import * from sqlalchemy.orm import * from sqlalchemy.orm.shard import ShardedSession from sqlalchemy.sql import operators +from sqlalchemy import sql import datetime # step 2. databases @@ -107,7 +108,7 @@ shard_lookup = { # note that we need to define conditions for # the WeatherLocation class, as well as our secondary Report class which will # point back to its WeatherLocation via its 'location' attribute. -def shard_chooser(mapper, instance): +def shard_chooser(mapper, instance, clause=None): if isinstance(instance, WeatherLocation): return shard_lookup[instance.continent] else: diff --git a/lib/sqlalchemy/orm/session.py b/lib/sqlalchemy/orm/session.py index b616570ab..6f06474b7 100644 --- a/lib/sqlalchemy/orm/session.py +++ b/lib/sqlalchemy/orm/session.py @@ -488,20 +488,19 @@ class Session(object): If this ``Session`` is transactional, the connection will be in the context of this session's transaction. Otherwise, the - connection is returned by the ``contextual_connect()`` method, which - some Engines override to return a thread-local connection, and - will have `close_with_result` set to `True`. - - The given `**kwargs` will be sent to the engine's - ``contextual_connect()`` method, if no transaction is in - progress. + connection is returned by the ``contextual_connect()`` method + on the engine. the "mapper" argument is a class or mapper to which a bound engine will be located; use this when the Session itself is either bound to multiple engines or connections, or is not bound to any connectable. + + \**kwargs are additional arguments which will be passed to get_bind(). + See the get_bind() method for details. Note that the "ShardedSession" + subclass takes a different get_bind() argument signature. """ - return self.__connection(self.get_bind(mapper)) + return self.__connection(self.get_bind(mapper, **kwargs)) def __connection(self, engine, **kwargs): if self.transaction is not None: @@ -592,8 +591,23 @@ class Session(object): self.__binds[table] = bind - def get_bind(self, mapper, clause=None): - + def get_bind(self, mapper, clause=None, **kwargs): + """return an engine corresponding to the given arguments. + + mapper + mapper relative to the desired operation + + clause + a ClauseElement which is to be executed. if + mapper is not present, this may be used to locate + Table objects, which are then associated with mappers + which have associated binds. + + \**kwargs + Subclasses (i.e. ShardedSession) may add additional arguments + to get_bind() which are passed through here. + """ + if mapper is None and clause is None: if self.bind is not None: return self.bind diff --git a/lib/sqlalchemy/orm/shard.py b/lib/sqlalchemy/orm/shard.py index 752806c0c..48e057966 100644 --- a/lib/sqlalchemy/orm/shard.py +++ b/lib/sqlalchemy/orm/shard.py @@ -9,11 +9,11 @@ class ShardedSession(Session): """construct a ShardedSession. shard_chooser - a callable which, passed a Mapper and a mapped instance, returns a - shard ID. this id may be based off of the attributes present within the - object, or on some round-robin scheme. If the scheme is based on a - selection, it should set whatever state on the instance to mark it in - the future as participating in that shard. + a callable which, passed a Mapper, a mapped instance, and possibly a + SQL clause, returns a shard ID. this id may be based off of the + attributes present within the object, or on some round-robin scheme. If + the scheme is based on a selection, it should set whatever state on the + instance to mark it in the future as participating in that shard. id_chooser a callable, passed a query and a tuple of identity values, @@ -47,9 +47,9 @@ class ShardedSession(Session): else: return self.get_bind(mapper, shard_id=shard_id, instance=instance).contextual_connect(**kwargs) - def get_bind(self, mapper, shard_id=None, instance=None): + def get_bind(self, mapper, shard_id=None, instance=None, clause=None): if shard_id is None: - shard_id = self.shard_chooser(mapper, instance) + shard_id = self.shard_chooser(mapper, instance, clause=clause) return self.__binds[shard_id] def bind_shard(self, shard_id, bind): diff --git a/lib/sqlalchemy/orm/strategies.py b/lib/sqlalchemy/orm/strategies.py index 86be77ae0..1ece80616 100644 --- a/lib/sqlalchemy/orm/strategies.py +++ b/lib/sqlalchemy/orm/strategies.py @@ -196,8 +196,9 @@ class DeferredColumnLoader(LoaderStrategy): statement = sql.select([p.columns[0] for p in group], clause, from_obj=[localparent.mapped_table], use_labels=True) else: statement, params = create_statement() - - result = session.execute(statement, params, mapper=localparent) + + conn = session.connection(mapper=localparent, instance=instance) + result = conn.execute(statement, params) try: row = result.fetchone() for prop in group: diff --git a/test/orm/sharding/shard.py b/test/orm/sharding/shard.py index e82de73ea..c63a29e80 100644 --- a/test/orm/sharding/shard.py +++ b/test/orm/sharding/shard.py @@ -66,7 +66,7 @@ class ShardTest(PersistTest): 'South America':'south_america' } - def shard_chooser(mapper, instance): + def shard_chooser(mapper, instance, clause=None): if isinstance(instance, WeatherLocation): return shard_lookup[instance.continent] else: @@ -116,7 +116,8 @@ class ShardTest(PersistTest): self.temperature = temperature mapper(WeatherLocation, weather_locations, properties={ - 'reports':relation(Report, backref='location') + 'reports':relation(Report, backref='location'), + 'city': deferred(weather_locations.c.city), }) mapper(Report, weather_reports) |