django-db-retry 0.1.1

Adds support for database query retries

django-db-retry

Motivation

Main motivation - to avoid data loss.

Usually when you develop a project locally with a single user - everything works perfectly. Local network is super-stable, and simultaneous users doesn't bother you. When it comes to the real world - your application can (and definitely will) face network issues. Second case - deadlocks, which I personally see too often across different projects. And the only possible solution here to avoid the data-loss - to do a query retry.

IMPORTANT: Now this works ONLY WITH MYSQL. If someone requires postgres/other dbs support - please create an issue

Usage

Install: pip install django-db-retry

Choose your flow (or use both):

• Monkey-patch django methods globally
• Use a decorator

Monkey-patch:

IMPORTANT: global patching won't handle retries for atomic transactions. with_query_retry should be used

Add next code somewhere on the top level of your project

from django_db_retry import install as install_db_retries
install_db_retries()

Decorator

Can be used on top of any function/view and will do a retry if deadlock/network error will happen. Default number of retries is 5. This value can be configured by using the QueryRetry class (see example 2):

from django_db_retry import with_query_retry
from django.db.transaction import atomic

@with_query_retry
def some_view():
    query_0, query_1 = ...
    with atomic():
        query_0()
        query_1()
    return ...

Default number of retries is 5. It can be configured by creating your own retry decorator, e.g.

from django_db_retry import QueryRetry
from django.db.transaction import atomic

my_retry_decorator = QueryRetry(max_tries=100)

@my_retry_decorator
def some_view():
    query_0, query_1 = ...
    with atomic():
        query_0()
        query_1()
    return ...

Todo

• Deal with atomic transactions during global patching