Oracle Forms Developer – Form Builder Reference, Volume 1

Optimizer Hint property
Description
Specifies a hint string that Form Builder passes on to the RDBMS optimizer when constructing queries.
Using the optimizer can improve the performance of database transactions.
Applies to block
Set Designer, programmatically
Refer to Built-in
• GET_BLOCK_PROPERTY
• SET_BLOCK_PROPERTY
Restrictions:
Valid only for applications running against the Oracle7 Server or Oracle8 Server.
Usage Notes
Consider a form that contains a block named DeptBlock based on the DEPT table. If the end user enters
a criteria of " > 25 " for the DEPTNO column and executes the query, the default SELECT statement
that Form Builder generates to query the appropriate rows from the database is as follows:
SELECT DEPTNO,DNAME,LOC,ROWID
FROM DEPT
WHERE (DEPTNO > 25)
The designer can use SET_BLOCK_PROPERTY to set the Optimizer Hint property to request that the
Oracle7 Server attempt to optimize the SQL statement for best response time:
Set_Block_Property(’DeptBlock’,OPTIMIZER_HINT,’FIRST_ROWS’);
SELECT /*+ FIRST_ROWS */ DEPTNO,DNAME,LOC,ROWID
FROM DEPT
WHERE (DEPTNO > 25)
For more information on how to use this feature with Oracle7, refer to the following sources:
• Oracle7 Server Application Developer’s Guide, Chapter 5, "Tuning SQL Statements"
• Oracle7 Server Concepts Manual, Chapter 13, "The Optimizer"
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