what is UTL_RECOMP in Oracle

This script is particularly useful after a major-version upgrade that typically invalidates all PL/SQL and Java objects. Although invalid objects are recompiled automatically on use, it is useful to run this script prior to operation because this will either eliminate or minimize subsequent latencies due to on-demand automatic recompilation at runtime.

Parallel recompilation can exploit multiple CPUs to reduce the time taken to recompile invalid objects. The degree of parallelism is specified by the first argument to RECOMP_PARALLEL Procedure.

In general, a parallelism setting of one thread for each available CPU provides a good initial setting. However, please note that the process of recompiling an invalid object writes a significant amount of data to system tables and is fairly I/O intensive. A slow disk system may be a significant bottleneck and limit speedups available from a higher degree of parallelism.

Operational Notes

• This package uses the job queue for parallel recompilation. It temporarily disables existing jobs (by marking them broken) so that recompile jobs can be run instead.
• This package must be run using SQL*PLUS.
• You must be connected AS SYSDBA to run this script.
• This package expects the following packages to have been created with VALID status:
  • STANDARD (standard.sql)
  • DBMS_STANDARD (dbmsstdx.sql)
  • DBMS_JOB (dbmsjob.sql)
  • DBMS_RANDOM (dbmsrand.sql)
• There should be no other DDL on the database while running entries in this package. Not following this recommendation may lead to deadlocks.

Examples

Recompile all objects sequentially:

EXECUTE UTL_RECOMP.RECOMP_SERIAL();

Recompile objects in schema SCOTT sequentially:

EXECUTE UTL_RECOMP.RECOMP_SERIAL('SCOTT');

Recompile all objects using 4 parallel threads:

EXECUTE UTL_RECOMP.RECOMP_PARALLEL(4);

Recompile objects in schema JOE using the number of threads specified in the parameter JOB_QUEUE_PROCESSES:

EXECUTE UTL_RECOMP.RECOMP_PARALLEL(NULL, 'JOE');

Subprogram
Description


RECOMP_PARALLEL Procedure

Recompiles invalid objects in the database, or in a given schema, in parallel in dependency order


RECOMP_SERIAL Procedure

Recompiles invalid objects in a given schema or all invalid objects in the database







RECOMP_PARALLEL Procedure

This procedure is the main driver that recompiles invalid objects in the database, or in a given schema, in parallel in dependency order. It uses information in dependency$ to order recompilation of dependents after parents.

Syntax
UTL_RECOMP.RECOMP_PARALLEL(
   threads  IN   PLS_INTEGER DEFAULT NULL,
   schema   IN   VARCHAR2    DEFAULT NULL,
   flags    IN   PLS_INTEGER DEFAULT 0);


Parameters

Parameter
Description


threads

The number of recompile threads to run in parallel. If NULL, use the value of 'job_queue_processes'.


schema

The schema in which to recompile invalid objects. If NULL, all invalid objects in the database are recompiled.


flags

Flag values are intended for internal testing and diagnosability only.



Usage Notes

The parallel recompile exploits multiple CPUs to reduce the time taken to recompile invalid objects. However, please note that recompilation writes significant amounts of data to system tables, so the disk system may be a bottleneck and prevent significant speedups.





RECOMP_SERIAL Procedure

This procedure recompiles invalid objects in a given schema or all invalid objects in the database.

Syntax
UTL_RECOMP.RECOMP_SERIAL(
   schema   IN   VARCHAR2    DEFAULT NULL,
   flags    IN   PLS_INTEGER DEFAULT 0);


Parameters

Parameter
Description


schema

The schema in which to recompile invalid objects. If NULL, all invalid objects in the database are recompiled.


flags

Flag values are intended for internal testing and diagnosability only.