Oracle Built−in Packages- P153 ppsx

oname IN VARCHAR2, column_group IN VARCHAR2, sequence_no IN NUMBER, method IN VARCHAR2, {parameter_column_name IN dbms_repcat.varchar2s,| parameter_column_name IN VARCHAR2,} priority_group IN VARCHAR2 := NULL, function_name IN VARCHAR2 := NULL, comment IN VARCHAR2 := NULL); PROCEDURE DBMS_REPCAT.ADD_UNIQUE_RESOLUTION (sname IN VARCHAR2, oname IN VARCHAR2, constraint_name IN VARCHAR2, sequence_no IN NUMBER, method IN VARCHAR2, {parameter_column_name IN dbms_repcat.varchar2s, | parameter_column_name IN VARCHAR2,} comment IN VARCHAR2 := NULL); PROCEDURE DBMS_REPCAT.ADD_DELETE_RESOLUTION (sname IN VARCHAR2, oname IN VARCHAR2, sequence_no IN NUMBER, {parameter_column_name IN dbms_repcat.varchar2s, | parameter_column_name IN VARCHAR2,} function_name IN VARCHAR2 := NULL, comment IN VARCHAR2 := NULL); Parameters are summarized in the following table. Name Description sname Name of the schema containing the replicated schema. Defaults to current user. oname Name of the replicated table. column_group ADD_UPDATE_RESOLUTION only. Column group for which the conflict resolution method is being defined. constraint_name ADD_UNIQUE_RESOLUTION only. Name of the constraint name or unique index for which the conflict resolution method is being added. sequence_no Number indicating when this conflict resolution method should be applied relative to other methods defined for the same column group or priority group. method The conflict resolution method. Valid values are, • PRIORITY GROUP • SITE PRIORITY • USER FUNCTION or one of the methods in Table 16.14. parameter_column_name Comma−separated list of columns to be used to resolve the conflict (if VARCHAR2) or a PL/SQL table of column names. If column_group is passed, the column(s) passed to parameter_column_name [Appendix A] What's on the Companion Disk? 16.5.1 About Resolution Methods 751 must be in the group. A `*' indicates that all columns in the table or column group should be passed to the conflict resolution function, in alphabetical order. priority_group ADD_UPDATE_RESOLUTION only. If using a priority group or site priority group, the name of the group. function_name If designating a user−defined conflict resolution method, the name of the user function. comment Comment on the conflict resolution method, visible in the DBA_REPRESOLUTION data dictionary view. 16.5.1.1.1 Exception The ADD_<conflicttype>RESOLUTION procedure may raise the following exceptions: Name Number Description duplicatesequence −1 Resolution method already exists with sequence number sequence_no for this column or priority group invalidmethod −23340 Resolution method method does not exist invalidparameter −23342 Column(s) specified in parameter_column_name invalid missingcolumn −23334 Specified column(s) do not exist in table oname missingconstraint −23344 Constraint constraint_name specified in ADD_UNIQUE_RESOLUTION does not exist missingfunction −23341 User−defined function function_name does not exist missinggroup −23331 column_group does not exist missingobject −23308 Table oname does not exist in the replication group missingprioritygroup −23336 priority_group does not exist nonmasterdef −23312 Calling site is not the master definition site typefailure −23319 Datatype of one of the columns specified in parameter_column_name is not appropriate for the resolution method 16.5.1.1.2 Restrictions Note the following restrictions on calling ADD_<conflicttype>_RESOLUTION: • You must call this procedure from the master definition site. • After this call, you must generate replication support for the table passed to oname. 16.5.1.1.3 Examples The following examples illustrate how to assign various conflict resolution methods to replicated tables. These examples use the products table used in earlier examples; for convenience, we've included its description here again. Sql>desc products Name Null? Type −−−−−−−−−−−−−−−−−−−−− −−−−−−−−− −−− [Appendix A] What's on the Companion Disk? 16.5.1 About Resolution Methods 752 PRODUCT_ID NOT NULL NUMBER(9) PRODUCT_TYPE NOT NULL NUMBER(6) CATALOG_ID NOT NULL VARCHAR2(15) DESCRIPTION NOT NULL VARCHAR2(30) REV_LEVEL NOT NULL VARCHAR2(15) PRODUCTION_DATE NOT NULL DATE PRODUCTION_STATUS NOT NULL VARCHAR2(12) AUDIT_DATE NOT NULL DATE AUDIT_USER NOT NULL VARCHAR2(30) GLOBAL_NAME NOT NULL VARCHAR2(20) 16.5.1.1.4 Examples of ADD_UPDATE_RESOLUTION Assume that we have created a priority group PG_PRODUCTION_STATUS and have designated priorities to the full range of values for the column PRODUCTION_STATUS. The following call implements this priority group as the conflict handler that Oracle invokes first (because sequence_no = 1) when an update conflict occurs. BEGIN DBMS_REPCAT.ADD_UPDATE_RESOLUTION( sname => 'SPROCKET', oname => 'PRODUCTS', sequence_no => 1, method => 'PRIORITY GROUP', priority_group => 'PG_PRODUCTION_STATUS', comment => 'Update Res. 1 added on '||sysdate); END; This next call assigns the column group CG_PRODUCT_MFG_COLS as the second update conflict resolution handler for table products. Oracle invokes this resolution method if and only if the first method failed to resolve the conflict. BEGIN DBMS_REPCAT.ADD_UPDATE_RESOLUTION( sname => 'SPROCKET', oname => 'PRODUCTS', colunn_group => 'CG_PRODUCT_PRICE_COLS', method => 'LATEST TIMESTAMP', parameter_column_name => 'PRODUCTION_DATE', comment => 'Update Res. 2 added on '||sysdate); END; The following example assigns a third update conflict resolution handler to the products table. This handler would simply ignore an update if the first two conflict handlers failed to resolve it. BEGIN DBMS_REPCAT.ADD_UPDATE_RESOLUTION( sname => 'SPROCKET', oname => 'PRODUCTS', sequence_no => 3, method => 'DISCARD', comment => 'Update Res. 3 added on '||sysdate); END; 16.5.1.1.5 Examples of ADD_UNIQUE_RESOLUTION Uniqueness conflicts may occur during inserts; for example, two different sites may insert a record with the same primary key. While you can guard against this sort of conflict by partitioning primary key values among your sites, this design is not always possible. Note that if you wish to use the APPEND SITE NAME or APPEND SEQUENCE NUMBER methods, the column with the unique constraint must specify a character datatype (CHAR or VARCHAR2). This choice of datatype may not be appropriate for a primary key column. [Appendix A] What's on the Companion Disk? 16.5.1 About Resolution Methods 753 The following example configures the products table to discard records that result in uniqueness conflicts: BEGIN DBMS_REPCAT.ADD_UNIQUE_RESOLUTION( sname => 'SPROCKET', oname => 'PRODUCTS', constraint_name => 'PK_PRODUCTS', sequence_no => 1, method => 'DISCARD', parameter_column => 'PRODUCT_ID', comment => 'Unique Res. 1 added on '||sysdate); END; 16.5.1.1.6 Examples of ADD_DELETE_RESOLUTION As we have mentioned, Oracle does not provide any built−in conflict resolution techniques for delete conflicts. In fact, Oracle recommends that applications that use the advanced replication option avoid delete entirely, and simply use a status column to flag records as deleted. However, if you must delete rows, you can write your own conflict resolution method and assign it to your table. See the Section 16.5.1.1.7, "User−defined methods"" section later in this chapter. The following function serves as a delete conflict handler for the products table. It forces a delete against the table. CREATE OR REPLACE FUNCTION products_delete_handler ( old_product_id IN OUT NUMBER, Old_product_type IN OUT NUMBER, old_catalog_id IN OUT VARCHAR2, old_description IN OUT VARCHAR2, old_rev_level IN OUT VARCHAR2, old_production_date IN OUT DATE, old_production_status IN OUT VARCHAR2, old_audit_date IN OUT DATE, old_audit_user IN OUT VARCHAR2, old_global_name IN OUT VARCHAR2, ignore_discard_flag OUT BOOLEAN ) RETURN BOOLEAN IS BEGIN DELETE FROM products WHERE product_id = old_product_id; ignore_discard_flag := TRUE; RETURN TRUE; END products_delete_handler; This final example designates the function products_delete_handler from the previous example and a user−defined delete conflict handler for the PRODUCTS_TABLE: DECLARE param_col_list DBMS_REPCAT.VARCHAR2S; BEGIN param_col_list( 1) := 'PRODUCT_ID'; param_col_list( 2) := 'PRODUCT_TYPE'; param_col_list( 3) := 'CATALOG_ID'; param_col_list( 4) := 'DESCRIPTION'; param_col_list( 5) := 'REV_LEVEL'; param_col_list( 6) := 'PRODUCTION_DATE'; param_col_list( 7) := 'PRODUCTION_STATUS', param_col_list( 8) := 'AUDIT_DATE', param_col_list( 9) := 'AUDIT_USER', param_col_list(10) := 'GLOBAL_NAME', DBMS_REPCAT.ADD_DELETE_RESOLUTION( [Appendix A] What's on the Companion Disk? 16.5.1 About Resolution Methods 754 sname => 'SPROCKET', oname => 'PRODUCTS', sequence_no => 1, paramekter_column_name => param_col_list, function_name => 'PRODUCTS_DELETE_HANDLER', comment => 'Del handler 1 added on ' || sysdate); END; 16.5.1.1.7 User−defined methods User−defined methods must meet the following criteria: 1. Must be a PL/SQL function. 2. Must return BOOLEAN TRUE if successful, FALSE otherwise. 3. Must not perform DDL. 4. Must not perform transaction control (e.g., ROLLBACK). 5. Must not perform session control (e.g., ALTER SESSION). 6. Must not perform system control (e.g. ALTER SYSTEM). 7. Update handlers accept old, new, and current column values for columns specified in parameter_column_name parameter of ADD_UPDATE_RESOLUTION. Old and current column values are IN parameters, new column values are IN OUT parameters. 8. Delete handlers accept old column values as IN parameters for all table columns. 9. Uniqueness handlers accept new values as IN OUT parameters for columns specified in the parameter_column_name parameter of ADD_UNIQUE_RESOLUTION. 10. Last parameter is ignore_discard_flag OUT BOOLEAN, which is set to TRUE if new values are to be discarded, or FALSE if they are to be accepted. 16.5.1.2 The DBMS_REPCAT.DROP_<conflicttype>_RESOLUTION procedure The DROP_<conflicttype>_RESOLUTION procedure removes a conflict resolution type from a table. The value of <conflicttype> can be UPDATE, UNIQUE, DELETE. Here are the specifications: PROCEDURE DBMS_REPCAT.DROP_UPDATE_RESOLUTION (sname IN VARCHAR2, oname IN VARCHAR2, column_group IN VARCHAR2, sequence_no IN NUMBER) ; [Appendix A] What's on the Companion Disk? 16.5.1 About Resolution Methods 755 . of ADD_DELETE_RESOLUTION As we have mentioned, Oracle does not provide any built−in conflict resolution techniques for delete conflicts. In fact, Oracle recommends that applications that use the. group CG_PRODUCT_MFG_COLS as the second update conflict resolution handler for table products. Oracle invokes this resolution method if and only if the first method failed to resolve the conflict. BEGIN . PRODUCTION_STATUS. The following call implements this priority group as the conflict handler that Oracle invokes first (because sequence_no = 1) when an update conflict occurs. BEGIN DBMS_REPCAT.ADD_UPDATE_RESOLUTION(