Bulk update using Peewee library

user_10109777 0
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I'm trying to update many records inside a table using Peewee library. Inside a for loop, i fetch a single record and then I update it but this sounds awful in terms of performance so I need to do the update in bulk. Current code look like this:

usernames_to_update = get_target_usernames()
for username in usernames_to_update:
    user = User.get(User.username == username) # username is primary key
    if user.type == 'type_1':
        user.some_attr_1 = some_value_1
    elif user.type == 'type_2':
        user.some_attr_2 = some_value_2
    # elif ....
    user.save()

In the documentation, there is insert_many function but nothing like update_many. Searching around i came up with these solutions:

  1. Executing raw query using CASE: Link
  2. Using replace_many: Link
  3. Using update : Link

But i couldn't find any examples of how to use the second or third solution. Can somebody clarify how cases 2 and 3 can be used?

peewee sql-update mysql python
2 Answers

You want the .update() method:

query = User.update(validated=True).where(User.username.in_(usernames_to_update))
query.execute()

Edit: so you want to conditionally set the value during an update. You can use the Case helper. Untested:

some_value_1 = 'foo'
some_value_2 = 'bar'
case_stmt = Case(User.type, [
    ('type_1', some_value_1),
    ('type_2', some_value_2)])
query = User.update(some_field=case_stmt).where(User.username.in_(list_of_usernames))
query.execute()

Docs can be found here: http://docs.peewee-orm.com/en/latest/peewee/api.html#Case

user_2543460

The new best answer is to use the bulk_update() method found here:

with database.atomic():
    User.bulk_update(user_list, fields=['username'], batch_size=50)
user_55730740
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