Migrate model (Table) data from one database to another database in chunks

migrate_data.py

import sys

from django.core import serializers


def migrate(model, dest_db, size=2000, start=0, old_db="default"):
    """
    Migrate data from one database to another database in chunks
    Args:
    - model: Model class
    - dest_db: Destination database
    - size: Chunk size, default is 2000
    - start: The start of the chunk, default 0
    - old_db: The Old database, default is `default`
    """

    count = model.objects.using(old_db).count()
    print("%s objects in model %s" % (count, model))
    for i in range(start, count, size):
        print(i)
        sys.stdout.flush()
        original_data = model.objects.using(old_db).all()[i : i + size]
        original_data_json = serializers.serialize("json", original_data)
        new_data = serializers.deserialize("json", original_data_json, using=dest_db)
        for n in new_data:
            n.save(using=dest_db)

    print("copied all for: ", model)



for model in desired_models:
    migrate(model, dest_db)