Recompile the procedure in the SCOTT schema that shows employees. SQL> exec DBMS_DDL.ALTER_COMPILE ('PROCEDURE', USER, 'SHOWEMPS'); Notice that I pass in all arguments in uppercase to ensure a match. 2. Recompile the body of the empmaint package in the SALLY schema. SQL> exec DBMS_DDL.ALTER_COMPILE ('PACKAGE BODY', 'SALLY, 'EMPMAINT'); Here too, I pass in all arguments in uppercase to ensure a match. 3. Suppose that I had created a procedure as follows: CREATE OR REPLACE PROCEDURE "%$^abc" IS BEGIN END; / (Try it! You will discover that this syntax will be acceptable to the compiler! It turns out that if you enclose your identifier −− be it a table name, column name, program name or variable name −− in double quotes, all of the normal rules are suspended.) Then I can recompile this program with the following command: SQL> exec DBMS_DDL.ALTER_COMPILE ('PROCEDURE', USER, '%$^abc'); Strange, but true! 10.3.2.1.1 Exceptions The ALTER_COMPILE procedure may raise any of the following exceptions: ORA−20000 Insufficient privileges or object does not exist. You must either own the specified object or be granted the CREATE ANY PROCEDURE privilege. ORA−20001 Remote object, cannot compile. You can only recompile objects on the local database instance. ORA−20002 Bad value for object type. You need to provide one of the values listed in the previous section. Notice that these exceptions are not defined in the specification of the package. Instead, ALTER_COMPILE simply calls RAISE_APPLICATION_ERROR with one of the above error numbers. These error numbers may therefore conflict with your own −20NNN error number usages. If you embed calls to ALTER_COMPILE inside your application or utility, watch out for the confusion such conflicts can cause. 10.3.2.1.2 Example At first glance, you might say this of the ALTER_COMPILE procedure: "Why bother? The command is available in SQL*Plus. I'll just execute the ALTER PROCEDURE XXX COMPILE command when I need to recompile." [Appendix A] What's on the Companion Disk? 10.3.2 Compiling PL/SQL Objects 506 The big difference between that command and the ALTER_COMPILE procedure, of course, is that you can run the latter within a PL/SQL block or program. This allows you to apply the full power and flexibility of a procedural language to make the utility more useful. This technique is demonstrated by my recompile procedure, which follows. This program recompiles all stored PL/SQL objects that are identified by the parameters you provide to it. /* Filename on companion disk: recmpile.sp */* CREATE OR REPLACE PROCEDURE recompile (status_in IN VARCHAR2 := 'INVALID', name_in IN VARCHAR2 := '%', type_in IN VARCHAR2 := '%', schema_in IN VARCHAR2 := USER) IS v_objtype VARCHAR2(100); CURSOR obj_cur IS SELECT owner, object_name, object_type FROM ALL_OBJECTS WHERE status LIKE UPPER (status_in) AND object_name LIKE UPPER (name_in) AND object_type LIKE UPPER (type_in) AND owner LIKE UPPER (schema_in) ORDER BY DECODE (object_type, 'PACKAGE', 1, 'FUNCTION', 2, 'PROCEDURE', 3, 'PACKAGE BODY', 4); BEGIN FOR rec IN obj_cur LOOP IF rec.object_type = 'PACKAGE' THEN v_objtype := 'PACKAGE SPECIFICATION'; ELSE v_objtype := rec.object_type; END IF; DBMS_DDL.ALTER_COMPILE (v_objtype, rec.owner, rec.object_name); DBMS_OUTPUT.PUT_LINE ('Compiled ' || v_objtype || ' of ' || rec.owner || '.' || rec.object_name); END LOOP; END; / Here are a few interesting aspects to this procedure: • The default values are set up so that if you call recompile without any arguments, it will recompile all objects marked INVALID in your own schema. That seemed to be the most common usage for this utility, so why not design the interface to make that the easiest usage as well? • I translate the PACKAGE type to PACKAGE SPECIFICATION. I also order the objects retrieved so that they are compiled in the following order: package, function, procedure, and finally package body. I do this so that package specifications are compiled first, putting in place as many of the interfaces as possible, before moving on to the implementations of standalone programs and then package bodies. • [Appendix A] What's on the Companion Disk? 10.3.2 Compiling PL/SQL Objects 507 It was necessary to declare a local variable for the object type because the definition of the OBJECT_TYPE column in ALL_OBJECTS is as VARCHAR2(12). When I combine PACKAGE and SPECIFICATION into a single "type" for purposes of the recompilation, the new type is too big for the record−based field. • I call DBMS_OUTPUT.PUT_LINE to provide a "trace" of the recompilations that have taken place. • You can use wildcarded values in just about all of the arguments (name, type, owner) in order to perform just those recompilations that you need to perform. • I apply the UPPER function to all arguments. This will work (and make it easier to specify objects for recompilation) unless you use mixed case in your object names. So to recompile all invalid programs in my schema, I would enter this command: SQL> exec recompile To recompile only package bodies that are invalid, I would execute the following: SQL> exec recompile (type_in => 'PACKAGE BODY') 10.3.3 Computing Statistics for an Object Use the ANALYZE_OBJECT procedure to compute statistics for the specified table, index, or cluster. 10.3.3.1 The DBMS_DDL.ANALYZE_OBJECT procedure Here is the header for this procedure: PROCEDURE DBMS_DDL.ANALYZE_OBJECT (type IN VARCHAR2 ,schema IN VARCHAR2 ,name IN VARCHAR2 ,method IN VARCHAR2 ,estimate_rows IN NUMBER DEFAULT NULL ,estimate_percent IN NUMBER DEFAULT NULL ,method_opt IN VARCHAR2 DEFAULT NULL); Parameters are summarized in the following table. Parameter Description type The type of the database object. Legal values are TABLE, CLUSTER, or INDEX. schema The name of the schema containing the object for which you wish to compute statistics. If NULL, then the current schema is used. name The name of the object for which you wish to compute statistics. method Action to be taken by the program. ESTIMATE, DELETE, and COMPUTE are accepted values and are explained following. estimate_rows The number of rows to be used to perform the statistics estimate. Cannot be less than 1. Used only if method is ESTIMATE. estimate_percent The percentage of rows to be used to perform the statistics estimate. Ignored if [Appendix A] What's on the Companion Disk? 10.3.3 Computing Statistics for an Object 508 estimate_rows is non−NULL. Must be between 1 and 99. Used only if method is ESTIMATE. method_opt The method option, indicating which elements of the object will be analyzed. The schema and name arguments are case−sensitive. In almost every instance, the names of your PL/SQL objects are stored in uppercase. (Enclose those names in double quotes when creating the objects if you want mixed case). You will therefore need to specify the names in uppercase when you call COMPUTE_STATISTICS. This procedure offers a procedural equivalent to the SQL DDL statement: ANALYZE TABLE|CLUSTER|INDEX [<schema>.]<name> [<method>] STATISTICS [SAMPLE <n> [ROWS|PERCENT]] If the type you specify is not one of TABLE, CLUSTER, or INDEX, the procedure returns without taking action. NOTE: The type is not case−sensitive; it is always converted to uppercase. Here are the valid entries for the method argument, and the resulting activity. (Remember that when you pass one of these values, they must be enclosed in single quotes.) COMPUTE Exact statistics are computed based on the entire contents of the specified object. These values are then placed in the data dictionary. ESTIMATE Statistics are estimated. With this option, either estimate_rows or estimate_percent must be non−NULL. These values are then placed in the data dictionary. DELETE The statistics for this object are deleted from the data dictionary. Here are the valid method_opt entries and the resulting impact: FOR TABLE Collects statistics for the table. FOR ALL COLUMNS [SIZE N] Collects column statistics for all columns and scalar attributes. The size is the maximum number of partitions in the histogram, with a default of 75 and a maximum of 254. FOR ALL INDEXED COLUMNS [SIZE N} Collects column statistics for all indexed columns in the table. The size is the maximum number of partitions in the histogram, with a default of 75 and a maximum of 254. FOR ALL INDEXES Collects statistics for all indexes associated with the table. 10.3.3.1.1 Exceptions DBMS_DDL.ANALYZE_OBJECT may raise any of the following exceptions: ORA−20000 [Appendix A] What's on the Companion Disk? 10.3.3 Computing Statistics for an Object 509 Insufficient privileges or object does not exist. You must either own the specified object or be granted the CREATE ANY PROCEDURE privilege. ORA−20001 Bad value for object type. You must specify TABLE, INDEX, or CLUSTER. Notice that these exceptions are not defined in the specification of the package. Instead, ANALYZE_OBJECT simply calls RAISE_APPLICATION_ERROR with one of the above error numbers. These error numbers may therefore conflict with your own −20NNN error number usages. If you embed calls to ANALYZE_OBJECT inside your application or utility, watch out for the confusion such conflicts can cause. 10.3.4 Setting Referenceability of Tables When you create an object table, it automatically becomes referenceable, unless you use the OID AS clause when creating the table. The OID AS clause allows you to create an object table and to assign to the new table the same embedded object ID (EOID) as another object table of the same type. After you create a new table using the OID AS clause, you end up with two object tables with the same EOID; the new table is not referenceable, the original one is. All references that previously pointed to the objects in the original table still reference the same objects in the same original table. If you execute the ALTER_TABLE_REFERENCEABLE procedure of the DBMS_DDL package on the new table, it will make that table the referenceable table replacing the original one. Any references will then point to the objects in the new table instead of to the objects in the original table. With DBMS_DDL, available only in Oracle8, you can both make a table referenceable and reverse that step. 10.3.4.1 The DBMS_DDL. (Oracle8 only) To make a table referenceable, call the following procedure: PROCEDURE DBMS_DDL.ALTER_TABLE_REFERENCEABLE (table_name IN VARCHAR2 ,table_schema IN VARCHAR2 DEFAULT NULL ,affected_schema IN VARCHAR2 DEFAULT NULL); Parameters are summarized in the following table. Parameter Description table_name The name of the table to be made referenceable. You cannot use a synonym. The argument is case−sensitive. table_schema The schema containing the table to be made referenceable. If NULL, then the current schema is used. The argument is case−sensitive. affected_schema The schema that is to be affected by this change. If NULL, then the PUBLIC schema is used. In other words, the change takes effect in all schemas. The argument is case−sensitive. This program alters the specified object table, table_schema.table_name, so it becomes the referenceable table for the specified schema, affected_schema. This program is the equivalent of the following SQL statement, ALTER TABLE [<table_schema>.]<table_name> REFERENCEABLE FOR <affected_schema> which is currently neither supported nor available as a DDL statement. You can obtain this effect only through a call to the ALTER_TABLE_REFERENCEABLE built−in package. [Appendix A] What's on the Companion Disk? 10.3.4 Setting Referenceability of Tables 510 . original table. With DBMS_DDL, available only in Oracle8 , you can both make a table referenceable and reverse that step. 10.3.4.1 The DBMS_DDL. (Oracle8 only) To make a table referenceable, call. DDL statement. You can obtain this effect only through a call to the ALTER_TABLE_REFERENCEABLE built−in package. [Appendix A] What's on the Companion Disk? 10.3.4 Setting Referenceability