code: private void checkForNewShard(DBObject dbObj) {
          int shardNumber = m_tableDef.getShardNumber(dbObj);
          if (shardNumber > 0) {
              SpiderService.instance().verifyShard(m_tableDef, shardNumber);
          }
      }
docs: If object is sharded, see if we need to add a new column to the "current shards" row.