UTL_RECOMP

The UTL_RECOMP package recompiles invalid PL/SQL modules, invalid views, Java classes, indextypes and operators in a database, either sequentially or in parallel.

This chapter contains the following topics:

UTL_RECOMP Overview

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.

UTL_RECOMP Operational Notes

UTL_RECOMP has several operational notes.

This package uses the job queue for parallel recompilation.
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.

UTL_RECOMP Examples

These examples show various ways that UTL_RECOMP can recompile objects.

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');
```

Summary of UTL_RECOMP Subprograms

This table lists the UTL_RECOMP subprograms and briefly describes them.

Table 1 UTL_RECOMP Package Subprograms

Subprogram	Description
RECOMP_PARALLEL Procedure	Recompiles invalid objects in a given schema, or all invalid objects in the database, in parallel
RECOMP_SERIAL Procedure	Recompiles invalid objects in a given schema or all invalid objects in the database

RECOMP_PARALLEL Procedure

This procedure uses the information exposed in the DBA_Dependencies view to recompile invalid objects in the database, or in a given schema, in parallel.

Syntax

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

Parameters

Table 2 RECOMP_PARALLEL Procedure 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 UTL_RECOMP_COMPILED table is updated with objects that RECOMP_PARALLEL has attempted to compile, or that it has compiled so far. If you monitor the progress of the recompilation, then the number of objects should increase with time. These tables are used internally by RECOMP_PARALLEL to prevent an object from being compiled more than once.

Table 3 Tables Generated by UTL_RECOMP.RECOMP_PARALLEL

Table	Purpose
`UTL_RECOMP_ERRORS`	A table of objects that are sorted into groups, based on dependencies. It is used internally by `RECOMP_PARALLEL` to guide parallel recompilation.
`UTL_RECOMP_COMPILED`	A table of objects that `RECOMP_PARALLEL` has attempted to compile. It is used internally by recomp_parallel to prevent an object from being compiled more than once.
`UTL_RECOMP_COMP_IDX1`	An index created on `UTL_RECOMP_COMPILED`, which uses object number as the primary key.
`UTL_RECOMP_SKIP_LIST`	A table of objects that `RECOMP_PARALLEL` will not attempt to compile. Typical usage is for `RECOMP_PARALLEL` to call `UTL_RECOMP.POPULATE_UTL_RECOMP_SKIP_LIST` before the update starts so that this table is filled with previously identified invalid objects. Afterward, when `RECOMP_PARALLEL` is run after upgrade, it will not attempt to compile those previously identified invalid objects.

Table 4 Views Generated by UTL_RECOMP.RECOMP_PARALLEL

View	Purpose
`UTL_RECOMP_ALL_OBJECTS`	A view that includes all objects that can be compiled.
`UTL_RECOMP_INVALID_ALL`	A view that selects invalid objects from `UTL_RECOMP_ALL_OBJECTS` that have not been compiled and are not on the skip list.
`UTL_RECOMP_INVALID_SEQ`	A view that selects objects from `UTL_RECOMP_INVALID_ALL` that must be compiled sequentially.
`UTL_RECOMP_INVALID_PARALLEL`	A view that selects objects from `UTL_RECOMP_INVALID_ALL` that can be compiled in parallel.
`UTL_RECOMP_INVALID_JAVA_SYN`	A view that selects from `UTL_RECOMP_ALL_OBJECTS` objects that are invalid `JAVA` synonyms.
`UTL_RECOMP_CIRCULAR_MV`	A view that selects from `UTL_RECOMP_ALL_OBJECTS` materialized view objects that have a circular dependency chain.
`UTL_RECOMP_INVALID_MV`	A view that selects from `UTL_RECOMP_ALL_OBJECTS` materialized view objects that are invalid but don’t have a circular dependency chain.
`UTL_RECOMP_ALL_STUBS`	A view that includes all stub objects that have not been compiled, and are not on the skip list. When this view is used in `RECOMP_PARALLEL`, it is restricted to show only stubs in the current edition.

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

Table 5 RECOMP_SERIAL Procedure 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.