Ndtyjky

I'm packaging SQLAlchemy, among other things, for deployment onto AWS Lambda and am looking to reduce the size of the zipped project archive. I see in sqlalchemy/dialects that there are a list of dialects of SQL which SQLAlchemy supports:

48K ./firebird

48K ./sybase

88K ./sqlite

112K    ./oracle

124K    ./mssql

204K    ./mysql

240K    ./postgresql 

Are there any issues with removing dialects for which this project is not using? If I'm only using MySQL, I surely wouldn't need an sqlite dialect definition.

Or perhaps removing the tests under sqlalchemy/testing:

12K ./testing/engines.py

12K ./testing/fixtures.py

12K ./testing/profiling.py

16K ./testing/assertsql.py

16K ./testing/exclusions.py

16K ./testing/provision.py

20K ./testing/assertions.py

28K ./testing/requirements.py

36K ./testing/plugin

136K    ./testing/suite

I did a search for the word "dialects" in the SQLAlchemy github repo and the main module that stood out was SQLAlchemy.databases.__init__.py:

from ..dialects.sqlite import base as sqlite

from ..dialects.postgresql import base as postgresql

postgres = postgresql

from ..dialects.mysql import base as mysql

from ..dialects.oracle import base as oracle

from ..dialects.firebird import base as firebird

from ..dialects.mssql import base as mssql

from ..dialects.sybase import base as sybase





__all__ = (

    'firebird',

    'mssql',

    'mysql',

    'postgresql',

    'sqlite',

    'oracle',

    'sybase',

)

Which I changed to:

from ..dialects.mysql import base as mysql





__all__ = (

    'mysql',

)

I also modified the __all__ declaration in sqlalchemy.dialects.__init__.py. This:

__all__ = (

    'firebird',

    'mssql',

    'mysql',

    'oracle',

    'postgresql',

    'sqlite',

    'sybase',

)

to:

__all__ = (

    'mysql'

)

(I actually don't know if modifying those __all__ declarations is necessary. I didn't test it without doing it.)

I then deleted all of the sqlalchemy.dialects.* sub directories except for mysql and I was able to run few MySQL CRUD apps that I have sitting around without exception.

Also deleting the sqlalchemy.testing folder didn't cause any problems.

I tried to run a sqllite app and got sqlalchemy.exc.NoSuchModuleError: Can't load plugin: sqlalchemy.dialects:sqlite.

So it seems that with only having to modify one or two files, you can get away with it as long as only running on the dialect that you leave behind.

The main thing is that after removing the dialects, all of the tests for your application pass (assuming your test coverage is good) as I only tested on a pretty limited set of small ORM apps.