Hi,
I am using sqlalchemy in my pyramid application. I have situation here,
where I need to map a table on the fly in the application during run time.
I also dont want to re-map all tables, there are some table which are
defined using a declarative base. I need those mapping to remain as is. How
can we do this?. Does clear_mappers() remove even declarative base mapping ?
DBSession =
scoped_session(sessionmaker(extension=ZopeTransactionExtension()))
Base = declarative_base()
class User(Base):
__tablename__ ="youzer"
uid = Column(Integer,autoincrement=True, primary_key=True)
uname = Column(Text,nullable=False,index=True)
Just one of the tables as example. There are many tables that I need to map
for different request
class GroupOrder()
gtid = Column(Integer, autoincrement=True,primary_key=True)
group_id = Column(Integer,
ForeignKey("group.gid",ondelete="CASCADE"),nullable=False)
...
...
These groups can grow huge , so decision was made to shard these group
based on a hash. These are similar structured tables , with different names.
Tables
group_order_<shard1>
group_order_<shard1>
group_order_<shard1>
table_object = Table(<shard table name with similar structure>,
Base.metadata,
Column('gtid', Integer, primary_key=True),
Column('group_id', ForeignKey('group.gid',ondelete="CASCADE"),
nullable=False),
....
...
Based on the request, I need to map the GroupOrder to the concerned table
and process the request.
This is a uwsgi application will the clear_mapper affect other worker
threads. ?
Srikanth Bemineni
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http://www.sqlalchemy.org/
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