Sequence Project Showplan Operator 序列映射運算符

序列映射運算符會從一個已經排序的集合里通過不停添加集合里的列執行計算。

運算符根據一個或多個列的值把輸入集合分為多個片段。然后運算符一次輸出一個片段。

這些列在序列映射運算符里會被顯示為參數。

SQL Server支持四種類型函數：RANK, DENSE_RANK, ROW_NUMBER, NTILE

序列映射會生成有（一個序列映射）和（兩個片段）的執行計劃

The Sequence Project operator adds columns to perform computations over an ordered set. It divides the input set into segments based on the value of one or more columns. The operator then outputs one segment at a time. These columns are shown as arguments in the Sequence Project operator.

Microsoft SQL Server supports four types of functions: RANK, DENSE_RANK, ROW_NUMBER, and NTILE. Sequence Projectwill generate plans that have a Sequence Project and generally two segments.

Sequence Project is a physical and a logical operator.

https://msdn.microsoft.com/en-us/library/ms187041(v=sql.105).aspx