如何解释 sybase RESTRICT Operator (VA = 1)(4)(0)(0)(0)(0)

Question

谁能帮忙解释一下 restrict 运算符？

我了解 Sybase 限制运算符用于计算基于列的表达式。但是我仍然无法弄清楚查询计划中RESTRICT Operator的确切含义。

例如，下面是我的 sql 的查询计划片段。限制运算符（VA = 1）（4）（0）（0）（0）（0）：（4）（0）（0）（0）（0）是什么意思？

    10 operator(s) under root



   |ROOT:EMIT Operator (VA = 10)

   |

   |   |SCALAR AGGREGATE Operator (VA = 9)

   |   |  Evaluate Ungrouped COUNT AGGREGATE.

   |   |

   |   |   |N-ARY NESTED LOOP JOIN Operator (VA = 8) has 7 children.

   |   |   |

   |   |   |   |RESTRICT Operator (VA = 1)(4)(0)(0)(0)(0)

   |   |   |   |

   |   |   |   |   |SCAN Operator (VA = 0)

   |   |   |   |   |  FROM TABLE

   |   |   |   |   |  trade

   |   |   |   |   |  t

   |   |   |   |   |  Index : i1

   |   |   |   |   |  Forward Scan.

   |   |   |   |   |  Positioning by key.

   |   |   |   |   |  Keys are:

   |   |   |   |   |    order_number ASC

   |   |   |   |   |  Using I/O Size 16 Kbytes for index leaf pages.

   |   |   |   |   |  With LRU Buffer Replacement Strategy for index leaf pages.

   |   |   |   |   |  Using I/O Size 16 Kbytes for data pages.

   |   |   |   |   |  With LRU Buffer Replacement Strategy for data pages.

   |   |   |

   |   |   |   |SCAN Operator (VA = 2)

   |   |   |   |  FROM TABLE

   |   |   |   |  product

   |   |   |   |  mp

   |   |   |   |  Index : mp

   |   |   |   |  Forward Scan.

   |   |   |   |  Positioning by key.

   |   |   |   |  Keys are:

   |   |   |   |    prod_id ASC

   |   |   |   |  Using I/O Size 16 Kbytes for index leaf pages.

   |   |   |   |  With LRU Buffer Replacement Strategy for index leaf pages.

   |   |   |   |  Using I/O Size 16 Kbytes for data pages.

   |   |   |   |  With LRU Buffer Replacement Strategy for data pages.

   |   |   |

   |   |   |   |SCAN Operator (VA = 3)

   |   |   |   |  FROM TABLE

   |   |   |   |  Accounts

   |   |   |   |  a

   |   |   |   |  Index : i2

   |   |   |   |  Forward Scan.

   |   |   |   |  Positioning by key.

   |   |   |   |  Index contains all needed columns. Base table will not be read.

   |   |   |   |  Keys are:

   |   |   |   |    account ASC

   |   |   |   |  Using I/O Size 16 Kbytes for index leaf pages.

   |   |   |   |  With LRU Buffer Replacement Strategy for index leaf pages.

Answer 1

showplan 输出的一部分，如运算符后面的那些数字，是 ASE 优化器的内部结构。没有关于这些的记录信息，包含此信息是为了帮助技术支持解决问题。 'VA = n' 部分仅反映查询计划中每个运算符的唯一编号 'n'。

如何解释 sybase RESTRICT Operator (VA = 1)(4)(0)(0)(0)(0)

How to interpret sybase RESTRICT Operator (VA = 1)(4)(0)(0)(0)(0)

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