123 DBMS_SQLDIAG

Using DBMS_SQLDIAG

• Overview

• Constants

• Examples

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Overview

In the rare case that a SQL statement fails with a critical error, you can run the SQL Repair Advisor to try to repair the failed statement.This section covers the following topics:

• About the SQL Repair Advisor

• Running the SQL Repair Advisor

• Removing a SQL Patch

About the SQL Repair Advisor

You run the SQL Repair Advisor after a SQL statement fails with a critical error. The advisor analyzes the statement and in many cases recommends a patch to repair the statement. If you implement the recommendation, the applied SQL patch circumvents the failure by causing the query optimizer to choose an alternate execution plan for future executions.

Running the SQL Repair Advisor

You run the SQL Repair Advisor by creating and executing a diagnostic task using the CREATE_DIAGNOSIS_TASK and EXECUTE_DIAGNOSIS_TASK respectively. The SQL Repair Advisor first reproduces the critical error and then tries to produce a workaround in the form of SQL patch.

1. Identify the problem SQL statement

   Consider the SQL statement that gives a critical error:

   DELETE FROM t t1 WHERE t1.a = 'a' AND ROWID <> (SELECT MAX(ROWID) FROM t t2 WHERE t1.a= t2.a AND t1.b = t2.b AND t1.d=t2.d)
   
   

   You use the SQL Repair advisor to repair this critical error.

2. Create a diagnosis task

   Invoke DBMS_SQLDIAG. CREATE_DIAGNOSIS_TASK. You can specify an optional task name, an optional time limit for the advisor task, and problem type. In the example below, we specify the SQL text, the task name as 'error_task' and a problem type as 'DBMS_SQLDIAG.PROBLEM_TYPE_COMPILATION_ERROR'.

   DECLARE
       rep_out         CLOB;
       t_id            VARCHAR2(50);
     BEGIN
       t_id := DBMS_SQLDIAG.CREATE_DIAGNOSIS_TASK( 
         sql_text => 'DELETE FROM t t1 WHERE t1.a = ''a'' AND ROWID <> (SELECT MAX(ROWID) FROM t t2 WHERE t1.a= t2.a AND t1.b = t2.b AND t1.d=t2.d)',
         task_name => 'error_task',
         problem_type =>DBMS_SQLDIAG.PROBLEM_TYPE_COMPILATION_ERROR);
   
   

3. Execute the diagnosis task

   To execute the workaround generation and analysis phase of the SQL Repair Advisor, you call DBMS_SQLDIAG.EXECUTE_DIAGNOSIS_TASK with the task ID returned by the CREATE_DIAGNOSIS_TASK. After a short delay, the SQL Repair Advisor returns. As part of its execution, the SQL Repair Advisor keeps a record of its findings which can be accessed through the reporting facilities of SQL Repair Advisor.

   DBMS_SQLDIAG.EXECUTE_DIAGNOSIS_TASK (t_id);
   
   

4. Report the diagnosis task

   The analysis of the diagnosis task is accessed through dbms_sqldiag.report_diagnosis_task. If the SQL Repair Advisor was able to find a workaround, it recommends a SQL Patch. A SQL Patch is similar to a SQL profile but unlike the SQL Profile, it is used to workaround compilation or execution errors.

   rep_out := DBMS_SQLDIAG.REPORT_DIAGNOSIS_TASK (t_id, DBMS_SQLDIAG.TYPE_TEXT);
    
     DBMS_OUTPUT.PUT_LINE ('Report : ' ||  rep_out);
    
     END;
     /
   
   

5. Applying the patch

   If a patch recommendation is present in the report, you can run the ACCEPT_SQL_PATCH command to accept the patch by invoking DBMS_SQLDIAG.ACCEPT_SQL_PATCH. This procedure takes the task_name as an argument.

   EXECUTE DBMS_SQLDIAG.ACCEPT_SQL_PATCH(task_name => 'error_task', task_owner => 'SYS', replace => TRUE);
   
   

6. Test the patch

   Now that you have accepted the patch, you can rerun the SQL statement. This time, it will not give you the critical error. If you run 'explain plan' for this statement, you will see that a SQL patch was used to generate the plan.

   DELETE FROM t t1 WHERE t1.a = 'a' AND ROWID <> (select max(rowid) FROM t t2 WHERE t1.a= t2.a AND t1.b = t2.b AND t1.d=t2.d);
   
   

Removing a SQL Patch

In a situation where you obtained an official patch from Oracle to fix an error, or upgraded to the next patchset or release of Oracle which included the fix for the error, you call DBMS_SQLDIAG.DROP_SQL_PATCH with the patch name to drop the SQL patch. The patch name can be obtained from the explain plan section or by querying the view DBA_SQL_PATCHES.

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Constants

The DBMS_SQLDIAG package uses the constants shown in the following tables:

• Table 123-1, "DBMS_SQLDIAG Constants - SQLDIAG Advisor Name" describes the name of SQL repair advisor as seen by the advisor framework

• Table 123-2, "DBMS_SQLDIAG Constants - SQLDIAG Advisor Task Scope Parameter Values" describes SQLDIAG advisor task scope parameter values

• Table 123-3, "DBMS_SQLDIAG Constants - SQLDIAG Advisor time_limit Constants" describes SQLDIAG advisor time_limit constants

• Table 123-4, "DBMS_SQLDIAG Constants - Report Type (possible values) Constants" describes possible formats for a report

• Table 123-5, "DBMS_SQLDIAG Constants - Report Level (possible values) Constants" describes possible levels of detail in the report

• Table 123-6, "DBMS_SQLDIAG Constants - Report Section (possible values) Constants" describes possible report sections (comma delimited)

• Table 123-7, "DBMS_SQLDIAG Constants - Problem Type Constants" describes possible values for the problem_type parameter of the CREATE_DIAGNOSIS_TASK Functions

• Table 123-8, "DBMS_SQLDIAG Constants - Findings Filter Constants" describes possible values for the _sql_findings_mode parameter

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Examples

Patch Pack / Unpack

Patches can be exported out of one system and imported into another by means of a staging table, provided by subprograms in this package. Like with SQL diagnosis sets, the operation of inserting into the staging table is called a "pack", and the operation of creating patches from staging table data is termed the "unpack".

DBAs should perform a pack/unpack as follows:

1. Create a staging table owned by user 'SH' through a call to CREATE_STGTAB_SQLPATCH:

   EXEC DBMS_SQLDIAG.CREATE_STGTAB_SQLPATCH(
       table_name          =>  'STAGING_TABLE',
       schema_name         =>  'SH'); 
   
   

2. Call PACK_STGTAB_SQLPATCH one or more times to write SQL patch data into the staging table. In this case, copy data for all SQL patches in the DEFAULT category into a staging table owned by the current schema owner:

   EXEC DBMS_SQLDIAG.PACK_STGTAB_SQLPATCH(
       staging_table_name  =>  'STAGING_TABLE'); 
   
   

3. In this case, only a single SQL patch SP_FIND_EMPLOYEE is copied into a staging table owned by the current schema owner:

   EXEC DBMS_SQLDIAG.PACK_STGTAB_SQLPATCH(
       patch_name          =>  'SP_FIND_EMPLOYEE',
       staging_table_name  =>  'STAGING_TABLE'); 
   
   

   The staging table can then be moved to another system using either datapump, import/export commands or via a databaselink.

4. Call UNPACK_STGTAB_SQLPATCH to create SQL patches on the new system from the patch data in the staging table. In this case, change the name in the data for the SP_FIND_EMPLOYEE patch stored in the staging table to 'SP_FIND_EMP_PROD':

   exec dbms_sqldiag.remap_stgtab_sqlpatch(
      old_patch_name      =>  'SP_FIND_EMPLOYEE',
      new_patch_name      =>  'SP_FIND_EMP_PROD', 
   

Summary of DBMS_SQLDIAG Subprograms

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ACCEPT_SQL_PATCH Function & Procedure

This procedure accepts a recommended SQL patch as recommended by the specified SQL diagnosis task.

Syntax

DBMS_SQLDIAG.ACCEPT_SQL_PATCH (
   task_name      IN  VARCHAR2,
   object_id      IN  NUMBER := NULL,
   name           IN  VARCHAR2 := NULL,
   description    IN  VARCHAR2 := NULL,
   category       IN  VARCHAR2 := NULL,
   task_owner     IN  VARCHAR2 := NULL,
   replace        IN  BOOLEAN := FALSE,
   force_match    IN  BOOLEAN := FALSE)
 RETURN VARCHAR2;

DBMS_SQLDIAG.ACCEPT_SQL_PATCH (
   task_name      IN  VARCHAR2,
   object_id      IN  NUMBER := NULL,
   name           IN  VARCHAR2 := NULL,
   description    IN  VARCHAR2 := NULL,
   category       IN  VARCHAR2 := NULL,
   task_owner     IN  VARCHAR2 := NULL,
   replace        IN  BOOLEAN := FALSE,
   force_match    IN  BOOLEAN := FALSE);

Parameters

Return Values

Name of the SQL patch

Usage Notes

Requires CREATE ANY SQL PATCH privilege

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ALTER_SQL_PATCH Procedure

This procedure alters specific attributes of an existing SQL patch object.

Syntax

DBMS_SQLDIAG.ALTER_SQL_PATCH (
   name            IN  VARCHAR2,
   attribute_name  IN  VARCHAR2,
   value           IN  VARCHAR2);

Parameters

Usage Notes

Requires ALTER ANY SQL PATCH privilege

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CANCEL_DIAGNOSIS_TASK Procedure

This procedure cancels a diagnostic task.

Syntax

DBMS_SQLDIAG.CANCEL_DIAGNOSIS_TASK (
    taskname        IN   VARCHAR2); 

Parameters

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CREATE_DIAGNOSIS_TASK Functions

This function creates a diagnostic task in order to diagnose a single SQL statement. It returns a SQL diagnosis task unique name

Syntax

Prepares the diagnosis of a single statement given its text:

DBMS_SQLDIAG.CREATE_DIAGNOSIS_TASK (
    sql_text           IN   CLOB,
    bind_list          IN   sql_binds := NULL,
    user_name          IN   VARCHAR2  := NULL,
    scope              IN   VARCHAR2  := SCOPE_COMPREHENSIVE,
    time_limit         IN   NUMBER    := TIME_LIMIT_DEFAULT,
    task_name          IN   VARCHAR2  := NULL,
    description        IN   VARCHAR2  := NULL,
    problem_type       IN   NUMBER    := PROBLEM_TYPE_PERFORMANCE)
  RETURN VARCHAR2;

Prepares the diagnosis of a single statement from the Cursor Cache given its identifier:

DBMS_SQLDIAG.CREATE_DIAGNOSIS_TASK (
    sql_id             IN   VARCHAR2,
    plan_hash_value    IN   NUMBER    := NULL,
    scope              IN   VARCHAR2  := SCOPE_COMPREHENSIVE,
    time_limit         IN   NUMBER    := TIME_LIMIT_DEFAULT,
    task_name          IN   VARCHAR2  := NULL,
    description        IN   VARCHAR2  := NULL,
    problem_type       IN   NUMBER    := PROBLEM_TYPE_PERFORMANCE)
  RETURN VARCHAR2;

Prepares the diagnosis of a Sqlset:

DBMS_SQLDIAG.CREATE_DIAGNOSIS_TASK (
    sqlset_name       IN VARCHAR2,
    basic_filter      IN VARCHAR2 :=  NULL,
    object_filter     IN VARCHAR2 :=  NULL,
    rank1             IN VARCHAR2 :=  NULL,
    rank2             IN VARCHAR2 :=  NULL,
    rank3             IN VARCHAR2 :=  NULL,
    result_percentage IN NUMBER   :=  NULL,
    result_limit      IN NUMBER   :=  NULL,
    scope             IN VARCHAR2 :=  SCOPE_COMPREHENSIVE,
    time_limit        IN NUMBER   :=  TIME_LIMIT_DEFAULT,
    task_name         IN VARCHAR2 :=  NULL,
    description       IN VARCHAR2 :=  NULL,
    plan_filter       IN VARCHAR2 :=  'MAX_ELAPSED_TIME',
    sqlset_owner      IN VARCHAR2 :=  NULL,
    problem_type      IN NUMBER   := PROBLEM_TYPE_PERFORMANCE)  RETURN VARCHAR2;

Parameters

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CREATE_STGTAB_SQLPATCH Procedure

This procedure creates the staging table used for transporting SQL patches from one system to another.

Syntax

DBMS_SQLDIAG.CREATE_STGTAB_SQLPATCH (
   table_name       IN  VARCHAR2,
   schema_name      IN  VARCHAR2 := NULL,
   tablespace_name  IN  VARCHAR2 := NULL);

Parameters

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DROP_DIAGNOSIS_TASK Procedure

This procedure drops a diagnostic task.

Syntax

DBMS_SQLDIAG.DROP_DIAGNOSIS_TASK (
    taskname        IN   VARCHAR2); 

Parameters

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DROP_SQL_PATCH Procedure

This procedure drops the named SQL patch from the database.

Syntax

DBMS_SQLDIAG.DROP_SQL_PATCH (
   name     IN  VARCHAR2,   ignore   IN  BOOLEAN := FALSE);

Parameters

Usage Notes

Requires DROP ANY SQL PATCH privilege

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EXECUTE_DIAGNOSIS_TASK Procedure

This procedure executes a diagnostic task.

Syntax

DBMS_SQLDIAG.EXECUTE_DIAGNOSIS_TASK (
    taskname        IN   VARCHAR2); 

Parameters

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EXPLAIN_SQL_TESTCASE Function

This procedure explains a SQL test case.

Syntax

DBMS_SQLDIAG.EXPLAIN_SQL_TESTCASE (
    sqlTestCase        IN   CLOB)
  RETURN CLOB; 

Parameters

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EXPORT_SQL_TESTCASE Procedures

This procedure exports a SQL test case to a directory.

Syntax

This variant has to be provided with the SQL information.

DBMS_SQLDIAG.EXPORT_SQL_TESTCASE (
    directory          IN   VARCHAR2,
    sql_text           IN   CLOB,
    user_name          IN   VARCHAR2  := 'SYS',
    bind_list          IN   sql_binds :=  NULL,
    exportEnvironment  IN   BOOLEAN   :=  TRUE,
    exportMetadata     IN   BOOLEAN   :=  TRUE,
    exportData         IN   BOOLEAN   :=  TRUE,
    samplingPercent    IN   NUMBER    :=  100,
    ctrlOptions        IN   VARCHAR2  :=  NULL,
    timeLimit          IN   NUMBER    :=  0,
    testcase_name      IN   VARCHAR2  :=  NULL,
    testcase           IN OUT NOCOPY CLOB); 

This variant extracts the SQL information from an incident file.

DBMS_SQLDIAG.EXPORT_SQL_TESTCASE (
    directory          IN   VARCHAR2,
    incident_id        IN   VARCHAR2,
    exportEnvironment  IN   BOOLEAN   :=  TRUE,
    exportMetadata     IN   BOOLEAN   :=  TRUE,
    exportData         IN   BOOLEAN   :=  TRUE,
    samplingPercent    IN   NUMBER    :=  100,
    ctrlOptions        IN   VARCHAR2  :=  NULL,
    timeLimit          IN   NUMBER    :=  0,
    testcase_name      IN   VARCHAR2  :=  NULL,
    testcase           IN OUT NOCOPY CLOB);

This variant allow the SQL Test case to be generated from a cursor present in the cursor cache. Use V$SQL to get the SQL identifier and the SQL hash value.

DBMS_SQLDIAG.BUILD_SQL_TESTCASE (
    directory          IN   VARCHAR2,
    sql_id             IN   VARCHAR2,
    plan_hash_value    IN   NUMBER    := NULL,
    exportEnvironment  IN   BOOLEAN   :=  TRUE,
    exportMetadata     IN   BOOLEAN   :=  TRUE,
    exportData         IN   BOOLEAN   :=  TRUE,
    samplingPercent    IN   NUMBER    :=  100,
    ctrlOptions        IN   VARCHAR2  :=  NULL,
    timeLimit          IN   NUMBER    :=  0,
    testcase_name      IN   VARCHAR2  :=  NULL,
    testcase           IN OUT NOCOPY CLOB); 

Parameters

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EXPORT_SQL_TESTCASE_DIR_BY_INC Function

This function generates a SQL Test Case corresponding to the incident ID passed as an argument. It creates a set of scripts and dump file in the directory passed as an argument.

Syntax

DBMS_SQLDIAG.EXPORT_SQL_TESTCASE_DIR_BY_INC (
    incident_id        IN   NUMBER,
    directory          IN   VARCHAR2,
    exportEnvironment  IN   VARCHAR2 := 'TRUE',
    exportMetadata     IN   VARCHAR2 := 'TRUE',
    exportData         IN   VARCHAR2 := 'FALSE',
    samplingPercent    IN   VARCHAR2 := '100', 
    ctrlOptions        IN   VARCHAR2 := NULL)
 RETURN BOOLEAN;

Parameters

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EXPORT_SQL_TESTCASE_DIR_BY_TXT Function

This function generates a SQL Test Case corresponding to the SQL passed as an argument. It creates a set of scripts and dump files in the directory passed as an argument.

Syntax

DBMS_SQLDIAG.EXPORT_SQL_TESTCASE_DIR_BY_TXT (
    incident_id        IN   NUMBER,
    directory          IN   VARCHAR2,
    sql_text           IN   CLOB,
    user_name          IN   VARCHAR2 := 'SYS',
    exportEnvironment  IN   VARCHAR2 := 'TRUE',
    exportMetadata     IN   VARCHAR2 := 'TRUE',
    exportData         IN   VARCHAR2 := 'FALSE',
    samplingPercent    IN   VARCHAR2 := '100',     ctrlOptions        IN   VARCHAR2 := NULL)
  RETURN BOOLEAN;

Parameters

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GET_SQL Function

This function loads a sql_setrow from the trace file associated to an the given incident ID.

Syntax

DBMS_SQLDIAG.GET_SQL (
    incident_id  IN     VARCHAR2)
  RETURN SQLSET_ROW;

Parameters

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INCIDENTID_2_SQL Procedure

This procedure initializes a sql_setrow from an incident ID.

Syntax

DBMS_SQLDIAG.INCIDENTID_2_SQL (
    incident_id   IN     VARCHAR2,
    sql_stmt      OUT    SQLSET_ROW,
    problem_type  OUT    NUMBER, 
    err_code      OUT    BINARY_INTEGER,
    err_mesg      OUT    VARCHAR2);

Parameters

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INTERRUPT_DIAGNOSIS_TASK Procedure

This procedure interrupts a diagnostic task.

Syntax

DBMS_SQLDIAG.INTERRUPT_DIAGNOSIS_TASK (
    taskname        IN   VARCHAR2); 

Parameters

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PACK_STGTAB_SQLPATCH Procedure

This procedure packs SQL patches into the staging table created by a call to the CREATE_STGTAB_SQLPATCH Procedure.

Syntax

DBMS_SQLDIAG.UPPACK_STGTAB_SQLPATCH (
   patch_name            IN  VARCHAR2 := '%',
   patch_category        IN  VARCHAR2 := 'DEFAULT',
   staging_table_name    IN  VARCHAR2,
   staging_schema_owner  IN  VARCHAR2 := NULL);

Parameters

Usage Notes

• Requires: ADMINISTER SQL PLAN MANAGEMENT OBJECT privilege and INSERT privilege on the staging table

• By default, we move all SQL patches in category DEFAULT. See the Examples for details. Note that the subprogram issues a COMMIT after packing each SQL patch, so if an error is raised in mid-execution, some patches may be in the staging table.

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REPORT_DIAGNOSIS_TASK Function

This function reports on a diagnostic task. It returns a CLOB containing the desired report.

Syntax

DBMS_SQLDIAG.REPORT_DIAGNOSIS_TASK (
    taskname           IN   VARCHAR2,
    type               IN   VARCHAR2  := TYPE_TEXT,
    level              IN   VARCHAR2  := LEVEL_TYPICAL,
    section            IN   VARCHAR2  := SECTION_ALL,
    object_id          IN   NUMBER    := NULL,
    result_limit       IN   NUMBER    := NULL,
    owner_name         IN   VARCHAR2  := NULL)
  RETURN CLOB;

Parameters

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RESET_DIAGNOSIS_TASK Procedure

This procedure resets a diagnostic task.

Syntax

DBMS_SQLDIAG.RESET_DIAGNOSIS_TASK (
    taskname        IN   VARCHAR2); 

Parameters

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RESUME_DIAGNOSIS_TASK Procedure

This procedure resumes a diagnostic path.

Syntax

DBMS_SQLDIAG.RESUME_DIAGNOSIS_TASK (
    taskname        IN   VARCHAR2); 

Parameters

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SET_DIAGNOSIS_TASK_PARAMETER Procedure

This procedure is called to update the value of a SQL diagnosis parameter of type VARCHAR2. The task must be set to its initial state before calling this procedure. The diagnosis parameters that can be set by this procedure are:

• MODE : diag scope (comprehensive, limited)

• _SQLDIAG_FINDING_MODE : findings in the report (see "DBMS_SQLDIAG Constants - Findings Filter Constants" for possible values)

Syntax

DBMS_SQLDIAG.SET_DIAGNOSIS_TASK_PARAMETER (
    taskname           IN   VARCHAR2,
    parameter          IN   VARCHAR2,    value              IN   NUMBER);

Parameters

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UNPACK_STGTAB_SQLPATCH Procedure

This procedure unpacks from the staging table populated by a call to the PACK_STGTAB_SQLPATCH Procedure. It uses the patch data stored in the staging table to create patches on this system. Users can opt to replace existing patches with patch data when they exist already. In this case, note that it is only possible to replace patches referring to the same statement if the names are the same (see the ACCEPT_SQL_PATCH Function & Procedure).

Syntax

DBMS_SQLDIAG.UPPACK_STGTAB_SQLPATCH (
   patch_name            IN  VARCHAR2 := '%',
   patch_category        IN  VARCHAR2 := '%',
   replace               IN  BOOLEAN,
   staging_table_name    IN  VARCHAR2,
   staging_schema_owner  IN  VARCHAR2 := NULL);

Parameters

Usage Notes

• Requires: ADMINISTER SQL MANAGEMENT OBJECT privilege and SELECT privilege on the staging table

• By default, all SQL patches in the staging table are moved. The function commits after successfully loading each patch. If it fails in creating an individual patch, it raises an error and does not proceed to those remaining in the staging table.