数据库服务器分配给排序的虚拟共享内存的数量取决于要进行排序的行数、每一行的大小以及是否为服务器设置了PDQPIORIDY。

The amount of virtual Shared memory that the database server allocates for a sort depends on the number of rows to be sorted and the size of the row, and whether PDQPIORIDY is set for the server.

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要实现伪事实查询主题，就要在数据库中创建一个一行的表格，或者使用虚拟表，例如SYSDUMMY1在DB 2中使用SYSDUMMY1，或者在Oracle中使用Dual。

To implement a fake fact query subject, either create a one row table in the database or use a virtual table such as SYSDUMMY1 for DB2 or Dual for Oracle.

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在实现虚拟模式时，您需要跟踪数据模型中何时需要新行，以及何时回滚新行的添加操作。

When you are implementing virtual mode, you will need to track when a new row is needed in the data model and when to rollback the addition of the new row.

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