Support for read slaves

Hi @coleifer,

I’m using a master-slave(read-only) setup for our MySQL RDS. Currently, there’s no straightforward way to specify the database connection on the basis of SELECT vs other query types. I stumbled upon your read_slave module from playhouse extension v2.10.0 release of peewee.

Is it possible that I can use the same code to do it myself?

from peewee import *


class ReadSlaveModel(Model):
    @classmethod
    def _get_read_database(cls):
        if not getattr(cls._meta, 'read_slaves', None):
            return cls._meta.database
        current_idx = getattr(cls, '_read_slave_idx', -1)
        cls._read_slave_idx = (current_idx + 1) % len(cls._meta.read_slaves)
        return cls._meta.read_slaves[cls._read_slave_idx]

    @classmethod
    def select(cls, *args, **kwargs):
        query = super(ReadSlaveModel, cls).select(*args, **kwargs)
        query.database = cls._get_read_database()
        return query

    @classmethod
    def raw(cls, *args, **kwargs):
        query = super(ReadSlaveModel, cls).raw(*args, **kwargs)
        if query._sql.lower().startswith('select'):
            query.database = cls._get_read_database()
        return query

taken from https://github.com/coleifer/peewee/blob/2.10.2/playhouse/read_slave.py

Also, I’d like to know if there are any future plans to bring back the support for read slaves.

[aniljaiswal]

You basically create two connections, one for read and other for write. For read connection, you can specify the models to bind to the database.

[JishnuRamesh]

Got it. Thanks