DBCC FREESESSIONCACHE
DBCC FREEPROCCACHE
DBCC DROPCLEANBUFFERS

在对SQL查询执行性能分析之前.

然而,例如,后来的一个DROPCLEANBUFFERS：

Use DBCC DROPCLEANBUFFERS to test queries with a cold buffer cache
without shutting down and restarting the server.

To drop clean buffers from the buffer pool,first use CHECKPOINT to
produce a cold buffer cache. This forces all dirty pages for the
current database to be written to disk and cleans the buffers. After
you do this,you can issue DBCC DROPCLEANBUFFERS command to remove all
buffers from the buffer pool.

我猜,这意味着您将测试您的查询,就像它是在服务器中运行的第一个查询一样,因此查询的实际“现实生活”影响将会更低.

运行这三个命令以了解查询成本是否真的是可取的,还是让您获得与实时环境中实际查询时间无关的实证结果？