Megosztás a következőn keresztül:

SYS(3054) - Rushmore Query Optimization Level

  • Cikk

Enables or disables display of Rushmore optimization levels for queries.

SYS(3054 [, 0 | 1 | 11 | 2 | 12] [, cMEMVAR])

Return Values

Character

Parameters

  • 0
    (Default) Disables the display of Rushmore optimization levels.
  • 1
    Enables the display of the Rushmore filter optimization levels.
  • 11
    Enables the display of Rushmore join optimization levels.
  • 2
    Includes SQL statement with the display of the Rushmore filter optimization levels.
  • 12
    Includes SQL statement with the display of Rushmore join optimization levels.
  • cMEMVAR
    Specifies an undeclared or declared PUBLIC or LOCAL memory variable in which to store the showplan information. If you have not declared cMEMVAR, Visual FoxPro creates it as a PRIVATE variable.

Remarks

SYS(3054) returns the current Rushmore optimization level setting as a character string to the active screen or to a memory variable.

The showplan output displays the table alias as reference for table name.

Use SYS(3054) to improve query performance by determining the extent to which the query is optimized by Rushmore technology.

Issue SYS(3054, 1) to display the Rushmore filter optimization level after a query is executed. The filter optimization level is displayed in the active window.

The following table lists the three levels of Rushmore optimization:

Optimization Level Description
None The query could not be optimized with Rushmore technology.
Partial Some expressions in the query could be optimized with Rushmore technology. The index tags used for Rushmore optimization are listed.
Full The query was fully optimized with Rushmore technology. The index tags used for Rushmore optimization are listed.

If SYS(3054,1) indicates that a query could not be optimized or could be optimized only partially, you can modify the query to take advantage of Rushmore optimization.

Issue SYS(3054, 11) to display the Rushmore join optimization level after a query is executed. The optimization level is displayed in the active window.

Issue SYS(3054, 0) to stop display of the Rushmore optimization level after a query is executed.

For more information about Rushmore technology and optimizing queries, see Using Rushmore Query Optimization to Speed Data Access.

Example

The following code displays the Rushmore Optimization level after performing a query:

LOCAL cmemvar
=SYS(3054,11,"cmemvar")
SELECT * FROM HOME()+"labels.dbf"
? cmemvar

See Also

PUBLIC Command | LOCAL Command | PRIVATE Command | SELECT - SQL Command | Using Rushmore Query Optimization to Speed Data Access