Set PeriodicTask.name max_length = 191 to avoid issues with MySQL indexes.

Add readme

Add test settings

Remove index related changes

Author: dilin-sp

README.rst

@@ -229,6 +229,17 @@ pip command::
 
     $ pip install https://github.com/celery/django-celery-beat/zipball/master#egg=django-celery-beat
 
+Issues with mysql
+-----------------
+ If you want to run ``django-celery-beat`` with MySQL, you might run into some issues.
+
+ One such issue is when you try to run ``python manage.py migrate django_celery_beat``, you might get the following error::
+     django.db.utils.OperationalError: (1071, 'Specified key was too long; max key length is 767 bytes')
+ To get around this issue, you can set::
+     DJANGO_CELERY_BEAT_NAME_MAX_LENGTH=191
+ (or any other value if any other db other than MySQL is causing similar issues.)
+ max_length of **191** seems to work for MySQL.
+
 .. |build-status| image:: https://secure.travis-ci.org/celery/django-celery-beat.svg?branch=master
     :alt: Build status
     :target: https://travis-ci.org/celery/django-celery-beat

django_celery_beat/migrations/0001_initial.py

@@ -4,6 +4,7 @@
 
 from django.db import migrations, models
 import django.db.models.deletion
+from django.conf import settings
 
 
 class Migration(migrations.Migration):
@@ -71,8 +72,15 @@ class Migration(migrations.Migration):
                     auto_created=True, primary_key=True,
                     serialize=False, verbose_name='ID')),
                 ('name', models.CharField(
-                    help_text='Useful description', max_length=200,
-                    unique=True, verbose_name='name')),
+                    help_text='Useful description',
+                    max_length=getattr(
+                        settings,
+                        'DJANGO_CELERY_BEAT_NAME_MAX_LENGTH',
+                        200
+                    ),
+                    unique=True,
+                    verbose_name='name'
+                )),
                 ('task', models.CharField(
                     max_length=200, verbose_name='task name')),
                 ('args', models.TextField(

django_celery_beat/models.py

@@ -6,6 +6,7 @@
 import timezone_field
 from celery import schedules
 from celery.five import python_2_unicode_compatible
+from django.conf import settings
 from django.core.exceptions import MultipleObjectsReturned, ValidationError
 from django.core.validators import MaxValueValidator
 from django.db import models
@@ -248,8 +249,14 @@ class PeriodicTask(models.Model):
     """Model representing a periodic task."""
 
     name = models.CharField(
-        _('name'), max_length=200, unique=True,
-        help_text=_('Useful description'),
+        _('name'),
+        max_length=getattr(
+            settings,
+            'DJANGO_CELERY_BEAT_NAME_MAX_LENGTH',
+            200
+        ),
+        unique=True,
+        help_text=_('Useful description')
     )
     task = models.CharField(_('task name'), max_length=200)
     interval = models.ForeignKey(

t/proj/settings.py

@@ -122,3 +122,4 @@
 # https://docs.djangoproject.com/en/1.9/howto/static-files/
 
 STATIC_URL = '/static/'
+DJANGO_CELERY_BEAT_NAME_MAX_LENGTH = 191