return;
  }
  db_multi_exec(
    "ALTER TABLE repository.pending_alert"
    " ADD COLUMN sentMod BOOLEAN DEFAULT false;"
  );
}

/*
** Process deferred alert events
*/
static int alert_process_deferred_triggers(void){
  if( db_table_exists("temp","deferred_chat_events")
   && db_table_exists("repository","chat")
  ){
    const char *zChatUser = db_get("chat-timeline-user", 0);
    if( zChatUser && zChatUser[0] ){
      db_multi_exec(
        "INSERT INTO chat(mtime,xfrom,xmsg)"
        " SELECT julianday(), %Q,"
               " chat_msg_from_event(type, objid, user, comment)\n"
        "   FROM deferred_chat_events;\n",
        zChatUser
      );
    }
  }
  return 0;
}

/*
** Enable triggers that automatically populate the pending_alert
** table. (Later:) Also add triggers that automatically relay timeline
** events to chat, if chat is configured for that.
*/
void alert_create_trigger(void){
  if( db_table_exists("repository","pending_alert") ){
    db_multi_exec(
      "DROP TRIGGER IF EXISTS repository.alert_trigger1;\n" /* Purge legacy */
      "CREATE TRIGGER temp.alert_trigger1\n"
      "AFTER INSERT ON repository.event BEGIN\n"
      "  INSERT INTO pending_alert(eventid)\n"
      "    SELECT printf('%%.1c%%d',new.type,new.objid) WHERE true\n"
      "    ON CONFLICT(eventId) DO NOTHING;\n"
      "END;"
    );
  }
  if( db_table_exists("repository","chat") ){
    const char *zChatUser = db_get("chat-timeline-user", 0);
    if( zChatUser && zChatUser[0] ){
      db_multi_exec(
         "CREATE TRIGGER temp.chat_trigger1\n"
         "AFTER INSERT ON repository.event BEGIN\n"
         "  INSERT INTO chat(mtime,xfrom,xmsg)"
  if( db_table_exists("repository","chat")
   && db_get("chat-timeline-user", "")[0]!=0 
  ){
    /* Record events that will be relayed to chat, but do not relay
    ** them immediately, as the chat_msg_from_event() function requires
    ** that TAGXREF be up-to-date, and that has not happened yet when
    ** the insert into the EVENT table occurs. */
    db_multi_exec(
       "CREATE TABLE temp.deferred_chat_events(\n"
       "  type TEXT,\n"
       "  objid INT,\n"
       "  user TEXT,\n"
       "  comment TEXT\n"
       ");\n"
       "CREATE TRIGGER temp.chat_trigger1\n"
       "AFTER INSERT ON repository.event BEGIN\n"
       "  INSERT INTO deferred_chat_events"
         "  SELECT julianday(), %Q,"
                 " format('[%%.12s]: %%s', blob.uuid, new.comment)"
       "   VALUES(new.type,new.objid,new.user,new.comment);\n"
         "  FROM blob WHERE rid=new.objid;\n"
         "END;\n",
       "END;\n"
         zChatUser
      );
    );
    }
    db_commit_hook(alert_process_deferred_triggers, 1);
  }
}

/*
** Disable triggers the event_pending and chat triggers.
**
** This must be called before rebuilding the EVENT table, for example