zulip/zerver/migrations/0527_presencesequence.py

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# Generated by Django 5.0.5 on 2024-05-02 22:36
import django.db.models.deletion
from django.db import migrations, models
from django.db.backends.base.schema import BaseDatabaseSchemaEditor
from django.db.migrations.state import StateApps
def create_presence_sequence_for_old_realms(
apps: StateApps, schema_editor: BaseDatabaseSchemaEditor
) -> None:
Realm = apps.get_model("zerver", "Realm")
PresenceSequence = apps.get_model("zerver", "PresenceSequence")
max_id = Realm.objects.aggregate(models.Max("id"))["id__max"]
if max_id is None:
# Nothing to do if there are no rows yet.
return
BATCH_SIZE = 2000
lower_bound = 0
# Add a slop factor to make it likely we run past the end in case
# of new rows created while we run. Races with realm creation are
# pretty unlikely, and should throw an exception, so we should
# catch them.
max_id += BATCH_SIZE / 2
while lower_bound < max_id:
realm_ids = Realm.objects.filter(
id__gt=lower_bound,
id__lte=lower_bound + BATCH_SIZE,
# Filter to realm whose PresenceSequence does not exist, to avoid
# running into IntegrityError by trying to create duplicate PresenceSequence.
presencesequence=None,
).values_list("id", flat=True)
PresenceSequence.objects.bulk_create(
PresenceSequence(realm_id=realm_id, last_update_id=0) for realm_id in realm_ids
)
lower_bound += BATCH_SIZE
class Migration(migrations.Migration):
atomic = False
dependencies = [
("zerver", "0526_user_presence_backfill_last_update_id_to_0"),
]
operations = [
migrations.CreateModel(
name="PresenceSequence",
fields=[
(
"id",
models.AutoField(
auto_created=True, primary_key=True, serialize=False, verbose_name="ID"
),
),
("last_update_id", models.PositiveBigIntegerField()),
(
"realm",
models.OneToOneField(
on_delete=django.db.models.deletion.CASCADE, to="zerver.realm"
),
),
],
),
migrations.RunPython(
create_presence_sequence_for_old_realms,
reverse_code=migrations.RunPython.noop,
elidable=True,
),
]