snapshot of https://github.com/zulip/zulip.git @ 48c69911c7dd4e03b20552eb3bd77ad8151c1357 (2026-09-15)

zerver/migrations/0527_presencesequence.py

@@ -0,0 +1,76 @@
+# 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,
+        ),
+    ]