django-bulk-update-or-create

Everyone using Django ORM will eventually find himself doing batch update_or_create operations: ingest files from external sources, sync with external APIs, etc.

If the number of records is big, the slowliness of QuerySet.update_or_create will stand out: it is very practical to use but it always does one SELECT and then one INSERT (if select didn't return anything) or UPDATE/.save (if it did).

Searching online shows that this does indeed happen to quite a few people though it doesn't seem to be any good solution:

• bulk_create is really fast if you know all records are new (and you're not using multi-table inheritance)
• bulk_update does some nice voodoo to update several records with the same UPDATE statement (using a huge WHERE condition together with CASE), but you need to be sure they all exist
• UPSERTs (INSERT .. ON DUPLICATE KEY UPDATE) look interesting (TODO on different package) but they will be retricted by bulk_create limitations ==> cannot use on models with multi-table inheritance

This package tries to tackle this introducing bulk_update_or_create to model QuerySet/Manager:

• update_or_create: (1 SELECT + 1 INSERT/UPDATE) * N
• bulk_update_or_create: 1 BIG_SELECT + 1 BIG_UPDATE + (lte_N) INSERT

For a batch of records:

• SELECT all from database (based on the match_field parameter)
• Update records in memory
• Use bulk_update for those
• Use INSERT/.create on each of the remaining

The (SOFTCORE) performance test looks promising, more than 70% less time (average):

$ make testcmd
# default - sqlite
DJANGO_SETTINGS_MODULE=settings tests/manage.py bulk_it
loop of update_or_create - all creates: 3.966486692428589
loop of update_or_create - all updates: 4.020653247833252
loop of update_or_create - half half: 3.9968857765197754
bulk_update_or_create - all creates: 2.949239730834961
bulk_update_or_create - all updates: 0.15633511543273926
bulk_update_or_create - half half: 1.4585723876953125
# mysql
DJANGO_SETTINGS_MODULE=settings_mysql tests/manage.py bulk_it
loop of update_or_create - all creates: 5.511938571929932
loop of update_or_create - all updates: 5.321666955947876
loop of update_or_create - half half: 5.391834735870361
bulk_update_or_create - all creates: 1.5671980381011963
bulk_update_or_create - all updates: 0.14612770080566406
bulk_update_or_create - half half: 0.7262606620788574
# postgres
DJANGO_SETTINGS_MODULE=settings_postgresql tests/manage.py bulk_it
loop of update_or_create - all creates: 4.3584535121917725
loop of update_or_create - all updates: 3.6183276176452637
loop of update_or_create - half half: 4.145816087722778
bulk_update_or_create - all creates: 1.044851541519165
bulk_update_or_create - all updates: 0.14954638481140137
bulk_update_or_create - half half: 0.8407495021820068

Installation

pip install django-bulk-update-or-create

INSTALLED_APPS = [
    ...
    'bulk_update_or_create',
    ...
]

Usage

• use BulkUpdateOrCreateQuerySet as manager of your model(s)

from django.db import models
from bulk_update_or_create import BulkUpdateOrCreateQuerySet

class RandomData(models.Model):
    objects = BulkUpdateOrCreateQuerySet.as_manager()

    uuid = models.IntegerField(unique=True)
    data = models.CharField(max_length=200, null=True, blank=True)

• call bulk_update_or_create

items = [
    RandomData(uuid=1, data='data for 1'),
    RandomData(uuid=2, data='data for 2'),
]
RandomData.objects.bulk_update_or_create(items, ['data'], match_field='uuid')

• or use the context manager, if you are updating a big number of items, as it manages a batch queue

with RandomData.objects.bulk_update_or_create_context(['data'], match_field='uuid', batch_size=10) as bulkit:
    for i in range(10000):
        bulkit.queue(RandomData(uuid=i, data=i + 20))

bulk_update_or_create supports yield_objects=True so you can iterate over the created/updated objects.
bulk_update_or_create_context provides the same information to the callback function specified as status_cb

Docs

WIP

ToDo

• [ ] Docs!
• [ ] Add option to use bulk_create for creates: assert model is not multi-table, if enabled
• [ ] Fix the collation mess: the keyword arg case_insensitive_match should be dropped and collation detected in runtime
• [x] Add support for multiple match_field - probably will need to use WHERE (K1=X and K2=Y) or (K1=.. and K2 =..) instead of IN for those, as that SQL standard doesn't seem widely adopted yet
• [ ] Link to UPSERT alternative package once done!