- Transformation rules in oracle apex sql query return value how to#
- Transformation rules in oracle apex sql query return value upgrade#
- Transformation rules in oracle apex sql query return value full#
This access path is available for statements that join tables stored in the same cluster if both of the following conditions are true: The EXPLAIN PLAN output for this statement might look like this: OPERATION OPTIONS OBJECT_NAME To execute the statement, Oracle accesses the table by rowid.įor example: SELECT * FROM emp WHERE ROWID = 'AAAA7bAA5AAAA1UAAA' This access path is available only if the statement's WHERE clause identifies the selected rows by rowid or with the CURRENT OF CURSOR embedded SQL syntax supported by the Oracle precompilers.
Transformation rules in oracle apex sql query return value full#
RBO Path 15: Full Table Scan Details of the RBO Access PathsĮach of the following sections describes an access path, discusses when it is available, and shows the output generated for it by the EXPLAIN PLAN statement. RBO Path 13: MAX or MIN of Indexed Column RBO Path 11: Unbounded Range Search on Indexed Columns RBO Path 10: Bounded Range Search on Indexed Columns RBO Path 4: Single Row by Unique or Primary Key RBO Path 3: Single Row by Hash Cluster Key with Unique or Primary Key The list shows access paths and their ranking: Usually, operations of lower rank execute faster than those associated with constructs of higher rank. If there is more than one way to execute a SQL statement, then the RBO always uses the operation with the lower rank. Oracle's ranking of the access paths is heuristic. Using the RBO, the optimizer chooses an execution plan based on the access paths available and the ranks of these access paths.
Transformation rules in oracle apex sql query return value how to#
You can also use this value if you want to collect and examine statistics for data without using the cost-based approach.Ĭhapter 3, "Gathering Optimizer Statistics" for an explanation of how to gather statistics You can then return to the RBO by deleting the statistics or by setting either the value of the OPTIMIZER_MODE initialization parameter or the OPTIMIZER_MODE clause of the ALTER SESSION statement to RULE. You can enable the CBO on a trial basis simply by collecting statistics. Migrate existing applications to use the cost-based approach. If OPTIMIZER_MODE= FIRST_ROWS, FIRST_ROWS_ n, or ALL_ROWS and no statistics exist, then the CBO uses default statistics. You can use the RBO to access both relational data and object types.
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If OPTIMIZER_MODE= CHOOSE, if statistics do not exist, and if you do not add hints to SQL statements, then SQL statements use the RBO. If you are using applications provided by third-party vendors, then check with the vendors to determine which type of optimizer is best suited to that application.
Transformation rules in oracle apex sql query return value upgrade#
If you have developed OLTP applications using Oracle version 6, and if you have tuned the SQL statements carefully based on the rules of the optimizer, then you might want to continue using the RBO when you upgrade these applications to a new Oracle release.