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What is cursor SHARING?
The CURSOR_SHARING parameter basically influences the extent to which SQL statements (or cursors) can be shared. So basically it means that the SQL statement will be shared even though literals are different as long as it does not affect the execution plan of the statement. This is the case for SIMILAR setting.
How to set CURSOR_SHARING in oracle?
Execute the following command: ALTER SYSTEM SET CURSOR_SHARING=FORCE SCOPE=BOTH; This will set the value immediately and also make it permanent across shutdown/startup. You must also shutdown and restart the application server or cluster for this to fully take effect.
How do I turn off adaptive cursor sharing?
Adaptive cursor sharing in Oracle
- Check Status of Adaptive cursor sharing. col parameter for a35.
- Disable the Adaptive cursor sharing in Oracle. alter system set “_optimizer_adaptive_cursor_sharing”=false scope= both;
- Enable the Adaptive cursor sharing. alter system set “_optimizer_adaptive_cursor_sharing”=TRUE scope= both;
What is parent and child cursor in Oracle?
While parent cursor stores the SQL Text, the child cursor stores other important information related to SQL statement like: Environment details, Statistics details, Bind Variables details, Execution Plan details Bind Variables details.
Is bind aware Oracle?
Starting in release 11.1. 0.7 and beyond, using the bind_aware hint forces bind-aware cursor_sharing from the first execution of the SQL statement. By making the SQL statement bind aware, Oracle considers the bind variable value in determining whether to use the existing execution plan or generate a new execution plan.
What is the default value of cursor_sharing?
1.46 CURSOR_SHARING
| Property | Description |
|---|---|
| Parameter type | String |
| Syntax | CURSOR_SHARING = { EXACT | FORCE } |
| Default value | EXACT |
| Modifiable | ALTER SESSION , ALTER SYSTEM |
What is a child cursor?
Every parent cursor has one or more child cursors. A child cursor contains the execution plan, bind variables, metadata about objects referenced in the query, optimizer environment, and other information. In contrast to the parent cursor, the child cursor does not store the text of the SQL statement.
In which view child cursors of the query are stored?
PARENT CURSOR Parent cursors are represented in the view V$SQLAREA. VERSION_COUNT column in the v$sqlarea can tell us how many child cursors does this parent cursor have.
Is there a force setting for cursor sharing in Oracle?
If you set CURSOR_SHARING, then Oracle recommends the FORCE setting unless you are in a DSS environment. FORCE limits the growth of child cursors that can occur when the setting is SIMILAR. The value of the CURSOR_SHARING parameter has performance implications. Refer to Oracle Database Performance Tuning Guide…
CURSOR_SHARING determines what kind of SQL statements can share the same cursors. Forces statements that may differ in some literals, but are otherwise identical, to share a cursor, unless the literals affect the meaning of the statement.
How to disable adaptive cursor sharing in databases?
For these types of databases, the overhead of adaptive cursor sharing may be bypassed by disabling the adaptive cursor sharing feature. According to MOSC Bug 11657468.8, adaptive cursor sharing can be disabled by setting hidden parameters: Turn off adaptive cursor sharing: alter system set “cursor_sharing”=exact scope=both;
Do you set cursor sharing to similar or similar?
SIMILAR – Only equivalence conditions are converted to bind variables (WONUM=’1234′ is converted but WONUM LIKE ‘123%’ is not). You should at least set cursor_sharing to SIMILAR, but you will usually see much greater performance improvement by using FORCE.