    class Meta:
        indexes = [
            GinIndex("search_tsvector", fastupdate=False, name="zerver_message_search_tsvector"),
            models.Index(
                # For moving messages between streams or marking
                # streams as read.  The "id" at the end makes it easy
                # to scan the resulting messages in order, and perform
                # batching.
                "realm_id",
                "recipient_id",
                "id",
                name="zerver_message_realm_recipient_id",
            ),
            models.Index(
                # For generating digest emails and message archiving,
                # which both group by stream.
                "realm_id",
                "recipient_id",
                "date_sent",
                name="zerver_message_realm_recipient_date_sent",
            ),
            models.Index(
                # For exports, which want to limit both sender and
                # receiver.  The prefix of this index (realm_id,
                # sender_id) can be used for scrubbing users and/or
                # deleting users' messages.
                # Also used in send_welcome_bot_response
                "realm_id",
                "sender_id",
                "recipient_id",
                name="zerver_message_realm_sender_recipient",
            ),

Warm-up