zulip/zerver/migrations/0564_purge_nagios_messages.py

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import time
from django.conf import settings
from django.db import connection, migrations, transaction
from django.db.backends.base.schema import BaseDatabaseSchemaEditor
from django.db.migrations.state import StateApps
from psycopg2.sql import SQL, Literal
def purge_nagios_messages(apps: StateApps, schema_editor: BaseDatabaseSchemaEditor) -> None:
Realm = apps.get_model("zerver", "Realm")
UserProfile = apps.get_model("zerver", "UserProfile")
with connection.cursor() as cursor:
cursor.execute("SELECT MIN(id), MAX(id) FROM zerver_message")
(min_id, max_id) = cursor.fetchone()
if min_id is None:
return
bot_realm = Realm.objects.get(string_id=settings.SYSTEM_BOT_REALM)
nagios_bot_tuples = [
(settings.NAGIOS_SEND_BOT, settings.NAGIOS_RECEIVE_BOT),
(settings.NAGIOS_STAGING_SEND_BOT, settings.NAGIOS_STAGING_RECEIVE_BOT),
]
for sender_email, recipient_email in nagios_bot_tuples:
sender_id = UserProfile.objects.get(
delivery_email=sender_email, realm_id=bot_realm.id
).id
recipient_id = UserProfile.objects.get(
delivery_email=recipient_email, realm_id=bot_realm.id
).recipient_id
batch_size = 10000
while True:
with transaction.atomic():
# This query is an index only scan of the
# zerver_message_realm_sender_recipient_id index
message_id_query = SQL(
"""
SELECT id
FROM zerver_message
WHERE realm_id = {realm_id}
AND sender_id = {sender_id}
AND recipient_id = {recipient_id}
ORDER BY id ASC
LIMIT {batch_size}
FOR UPDATE
"""
).format(
realm_id=bot_realm.id,
sender_id=sender_id,
recipient_id=recipient_id,
batch_size=Literal(batch_size),
)
cursor.execute(message_id_query)
message_ids = [id for (id,) in cursor.fetchall()]
if not message_ids:
break
message_id_str = SQL(",").join(map(Literal, message_ids))
cursor.execute(
SQL(
"DELETE FROM zerver_usermessage WHERE message_id IN ({message_ids})"
).format(message_ids=message_id_str)
)
# We do not expect any attachments, but for
# correctness, we ensure they are detached before
# deleting the messages
cursor.execute(
SQL(
"DELETE FROM zerver_attachment_messages WHERE message_id IN ({message_ids})"
).format(message_ids=message_id_str)
)
cursor.execute(
SQL("DELETE FROM zerver_message WHERE id IN ({message_ids})").format(
message_ids=message_id_str
)
)
time.sleep(0.1)
class Migration(migrations.Migration):
atomic = False
elidable = True
dependencies = [
("zerver", "0563_zulipinternal_can_delete"),
]
operations = [migrations.RunPython(purge_nagios_messages)]