56 lines
1.7 KiB
Python
56 lines
1.7 KiB
Python
"""
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Adapted from:
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https://github.com/coleifer/peewee/blob/master/playhouse/read_slave.py
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Support for using a dedicated read-slave. The read database is specified as a
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Model.Meta option, and will be used for SELECT statements:
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master = PostgresqlDatabase('master')
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read_slave = PostgresqlDatabase('read_slave')
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class BaseModel(ReadSlaveModel):
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class Meta:
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database = master
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read_slaves = [read_slave] # This database will be used for SELECTs.
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# Now define your models as you would normally.
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class User(BaseModel):
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username = CharField()
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# To force a SELECT on the master database, you can instantiate the SelectQuery
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# by hand:
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master_select = SelectQuery(User).where(...)
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"""
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from peewee import *
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class ReadSlaveModel(Model):
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@classmethod
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def _get_read_database(cls):
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if (not getattr(cls._meta, 'read_slaves', None) or
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cls._meta.database.transaction_depth() > 0):
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return cls._meta.database
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current_idx = getattr(cls, '_read_slave_idx', -1)
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cls._read_slave_idx = (current_idx + 1) % len(cls._meta.read_slaves)
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selected_read_slave = cls._meta.read_slaves[cls._read_slave_idx]
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if isinstance(selected_read_slave, Proxy) and selected_read_slave.obj is None:
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# It's possible the read slave was disabled by not initializing it
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return cls._meta.database
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return selected_read_slave
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@classmethod
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def select(cls, *args, **kwargs):
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query = super(ReadSlaveModel, cls).select(*args, **kwargs)
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query.database = cls._get_read_database()
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return query
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@classmethod
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def raw(cls, *args, **kwargs):
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query = super(ReadSlaveModel, cls).raw(*args, **kwargs)
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if query._sql.lower().startswith('select'):
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query.database = cls._get_read_database()
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return query
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