ITPub博客

首页 > 数据库 > Oracle > Cell smart table scan等待事件

Cell smart table scan等待事件

Oracle 作者:kakaxi9521 时间:2021-07-28 09:53:18 1 删除 编辑

cell smart table scan This is an Exadata wait event typically seen during full table scans that have been offloaded to the storage cells. This event replaces waits on "direct path read" in many cases. As with direct path reads, data is returned directly to the PGA rather than going through the buffer cache. When the storage cells process full table scans they can apply columns filters and perform column projection so that not all blocks are returned, only the ones that are needed. Solutions This event indicates that a full table scan is being performed. In some cases this could be faster than an index lookup, but is not a replacement for query tuning. If the query will return a small subset of the data, utilizing an index may be more efficient. Test the differences to understand any performance penalties incurred by doing a smart table scan vs. the index lookup. Also, ensure the smart table scan is being done effectively by reviewing the Cell Smart Table Scan Latency metric on the Exadata tab under Resources in Ignite. The Objects tab in Ignite will also show response time information by object. This is critical for understanding which table is causing the majority of wait times.

来自 “ ITPUB博客 ” ,链接:http://blog.itpub.net/21374452/viewspace-2783700/,如需转载,请注明出处,否则将追究法律责任。

上一篇: sync_binlog
请登录后发表评论 登录
全部评论

注册时间:2009-04-13

  • 博文量
    119
  • 访问量
    120756