是否动态设置__tablename__以在SQLAlchemy中进行分片? [英] Dynamically setting __tablename__ for sharding in SQLAlchemy?

问题描述

为了处理不断增长的数据库表，我们对表名进行了分片.因此，我们可以将数据库表命名为:

In order to handle a growing database table, we are sharding on table name. So we could have database tables that are named like this:

table_md5one
table_md5two
table_md5three

所有表都具有完全相同的架构.

All tables have the exact same schema.

我们如何使用SQLAlchemy并为与此对应的类动态指定表名?看起来declarative_base()类需要预先指定 tablename .

How do we use SQLAlchemy and dynamically specify the tablename for the class that corresponds to this? Looks like the declarative_base() classes need to have tablename pre-specified.

最终将有太多表无法手动指定从父/基类派生的类.

There will eventually be too many tables to manually specify derived classes from a parent/base class. We want to be able to build a class that can have the tablename set up dynamically (maybe passed as a parameter to a function.)

推荐答案

好的，我们使用了自定义的SQLAlchemy声明，而不是声明性的声明.

OK, we went with the custom SQLAlchemy declaration rather than the declarative one.

因此我们创建一个动态表对象，如下所示:

So we create a dynamic table object like this:

from sqlalchemy import MetaData, Table, Column

def get_table_object(self, md5hash):
    metadata = MetaData()
    table_name = 'table_' + md5hash
    table_object = Table(table_name, metadata,
        Column('Column1', DATE, nullable=False),
        Column('Column2', DATE, nullable=False)
    )
    clear_mappers()
    mapper(ActualTableObject, table_object)
    return ActualTableObject

其中ActualTableObject是映射到表的类.

Where ActualTableObject is the class mapping to the table.

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