Menu
I'm under the impression that database calls through SQLAlchemy will block and aren't suitable for use in anything other than synchronous code. Am I correct (I hope I'm not!) or is there a way to configure it to be non-blocking?
383
Using a SQL BETWEEN operator will evaluate ranges in an inclusive manner. BETWEEN 10 AND 20 is the same as [10, 20]. To write a simple query that represents [10, 20), you can do the following as suggested by Ilja Everilä.
If you want to view your data in a more schema-centric view (as used in SQL), use Core. If you have data for which business objects are not needed, use Core. If you view your data as business objects, use ORM. If you are building a quick prototype, use ORM.
SQLAlchemy is great because it provides a good connection / pooling infrastructure; a good Pythonic query building infrastructure; and then a good ORM infrastructure that is capable of complex queries and mappings (as well as some pretty stone-simple ones).
SQLAlchemy is the ORM of choice for working with relational databases in python. The reason why SQLAlchemy is so popular is because it is very simple to implement, helps you develop your code quicker and doesn't require knowledge of SQL to get started.
You can use SQLA in a non-blocking style using gevent. Here's an example using psycopg2, using psycopg2's coroutine support:
https://bitbucket.org/zzzeek/green_sqla/
I've also heard folks use the same idea with pymysql. As pymysql is in pure Python and uses the sockets library, gevent patches the socket library to be asynchronous.
109
Have a look at Tornado as they've got some neat non-blocking libraries, particularly tornado.gen.
We use that along with Momoko, a non-blocking psycopg wrapper lib for Tornado. It's been great so far. Perhaps the only drawback is you lose all the model object stuff that SQLAlchemy gives you. Performance is unreal though.
25
Without the help of greenlet, the answer is no, in the context of asyncio.
However it is possible to use only a part of SQLAlchemy in asyncio. Please find example in the GINO project, where we used only SQLAlchemy core without engine and full execution context to make a simple ORM in asyncio.
45
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
