perf(hybridcloud): Skip correlated subqueries in user.serialize_many

[scttcper]

sentry/src/sentry/users/services/user/impl.py

Lines 358 to 375 in a8fcbce

	def base_query(self, select_related: bool = True) -> QuerySet[User]:
	if not select_related:
	return User.objects.all()
	return User.objects.extra(
	select={
	"permissions": "select array_agg(permission) from sentry_userpermission where user_id=auth_user.id",
	"roles": """
	SELECT array_agg(permissions)
	FROM sentry_userrole
	JOIN sentry_userrole_users
	ON sentry_userrole_users.role_id=sentry_userrole.id
	WHERE user_id=auth_user.id""",
	"useremails": "select array_agg(row_to_json(sentry_useremail)) from sentry_useremail where user_id=auth_user.id",
	"authenticators": "SELECT array_agg(row_to_json(auth_authenticator)) FROM auth_authenticator WHERE user_id=auth_user.id",
	"useravatar": "SELECT array_agg(row_to_json(sentry_useravatar)) FROM sentry_useravatar WHERE user_id = auth_user.id",
	}
	)

base_query() adds 5 correlated subqueries via .extra() (permissions, roles, useremails, authenticators, useravatar) that are only consumed by serialize_rpc_user() in the get_many path. serialize_many goes through the API serializer which re-queries the same data in get_attrs(), so the extra subqueries were pure overhead - the data was fetched, attached to the User objects, and then ignored.

Threads select_related through FilterQueryDatabaseImpl.serialize_many as an opt-in parameter and has the user service pass False. The select_related=False escape hatch already exists (added after #48088) and is used by get_many_ids and get_many_profiles, but serialize_many wasn't using it.

Context: #45564 moved base_query into FilterQueryDatabaseImpl, #48088 added the eager-loaded subqueries to fix N+1s in the serialize_rpc path.

[markstory]

Nice find 👏