 | Chapter 17 |  |
| Chapter 17 | |
Contents:
About Deferred Transactions and RPCs
DBMS_DEFER_SYS: Managing Deferred Transactions
DBMS_DEFER: Building Deferred Calls
DBMS_DEFER_QUERY: Performing Diagnostics and Maintenance
Oracle's advanced replication option relies primarily on deferred transactions and remote procedure calls (RPCs). When you commit a transaction against a replicated table, for example, the replication support triggers queue a deferred transaction to do your bidding in one or more remote databases. In addition to providing many of the underpinnings for the advanced replication option, the packages used to create and manipulate deferred calls are available for direct use in your applications. You will use the packages described in this chapter for deferred transactions and RPCs.
Performs administrative tasks such as scheduling, executing, and deleting queued transactions.
Builds deferred calls.
Provides access to parameters passed to deferred calls, primarily for diagnostic purposes.
NOTE: Users must have explicit EXECUTE privileges on DBMS_DEFER in order to create deferred calls.
This section provides some basic information you'll find useful in using the packages described in this chapter.
Every remote procedure call has to be executed somewhere, and Oracle offers several methods of specifying where.
If you are using the advanced replication option, you have implicitly named the destinations for deferred RPCs and transactions by creating master sites. Whenever a user performs DML on a table, the transaction is applied locally and is queued for delivery to all other sites where the table is replicated; these sites are listed in the DBA_REPSITES data dictionary view. Similarly, replicated procedure calls are also queued for all master sites in the replicated environment. Refer to Chapter 15, Advanced Replication, for details on using DBMS_REPCAT, which performs most replicated environment administration operations.
If you are not using the advanced replication option, then the destination site(s) are determined by one of the following means, listed in order of precedence:
The sites specified in the nodes parameter in the call to DBMS_DEFER.CALL, described later in this chapter.
The sites specified in the nodes parameter to DBMS_DEFER.TRANSACTION, described later in this chapter.
The sites specified in the DEFDEFAULTDEST data dictionary view, described later in this chapter (Table 17.4).
If Oracle cannot determine a call's destination by any of these methods, or if you specify differing destinations in the DBMS_DEFER.TRANSACTION and DBMS_DEFER.CALL procedures, the deferred call will raise an exception.
There are eight data dictionary views (see Table 17.1) that contain data about deferred transactions and RPCs. You can query these views to determine information such as the destination of RPC calls, error messages, and scheduled execution times. Most of the packages associated with deferred calls reference and/or modify the data in these views.
Tables 17-2 through 17-9 provide details about the contents of these views.
View Name | Description |
|---|---|
Contains information about all deferred RPCs. Queries SYSTEM.DEF$_CALL table. | |
Contains the destination database(s) for each deferred RPC in DEFCALL. Queries SYSTEM.DEF$_CALL, SYSTEM.DEF$_DESTINATION, SYSTEM.DEF$_CALLDEST, SYSTEM.DEF$_ERROR, and SYSTEM.REPCAT$_REPPROP. | |
Contains the default destinations for deferred RPCs. Queries SYSTEM.DEF$_DEFAULTDEST. | |
Contains error information for deferred calls that could not be applied at their destination. Queries SYSTEM. DEF$_ERROR. | |
Contains the count of errors for each destination. Queries SYSTEM.DEF$_ERROR. | |
Contains information about the scheduling of deferred jobs. Queries SYSTEM.DEF$_DESTINATION and SYS.JOB$. | |
Contains information about all deferred calls. Queries SYSTEM.DEF$_CALL and SYS.USER$. | |
Contains the destination database(s) for each deferred transaction. Queries SYSTEM.DEF$_CALL, SYSTEM.DEF$_DESTINATION, SYSTEM.DEF$_ERROR, SYSTEM.DEF$_CALLDEST, and SYSTEM.REPCAT$_REPPROP. |
Column Name | Description |
|---|---|
CALLNO | Unique ID of call at deferred_tran_db |
DEFERRED_TRAN_DB | Global name of database that originated the call |
DEFERRED_TRAN_ID | Unique ID of the transaction |
SCHEMANAME | Schema that owns the package |
PACKAGENAME | Name of the package |
PROCNAME | Name of the procedure within the package |
ARGCOUNT | Number of arguments passed to the procedure |
Column Name | Description |
|---|---|
CALLNO | Unique ID of call at deferred_tran_db. |
DEFERRED_TRAN_ID | Unique ID of the transaction. Note that each deferred_tran_id has one or more calls. |
DEFERRED_TRAN_DB | Global name of database that originated the call. |
DBLINK | Global name of the destination database. |
Column Name | Description |
|---|---|
DBLINK | Global name of the destination database |
Column Name | Description |
|---|---|
DEFERRED_TRAN_DB | Global name of the database that originated the RPC |
DEFERRED_TRAN_ID | ID of the transaction originating or copying the deferred RPC |
CALLNO | Unique ID of call at deferred_tran_db |
DESTINATION | Database link used to specify the destination database |
ERROR_TIME | Time the error occurred |
ERROR_NUMBER | Oracle error number |
ERROR_MSG | Error message text |
Column Name | Description |
|---|---|
ERRCOUNT | Number of errors in deferred RPC calls to destination |
DESTINATION | Global name of destination database |
Column Name | Description |
|---|---|
DBLINK | Global name of the database for which pushes of deferred RPC calls is scheduled |
JOB | Number of the job (job column in DBA_JOBS) |
INTERVAL | Date expression that determines how often the job runs |
NEXT_DATE | Next time the job is scheduled to run |
LAST_DATE | Last time the job ran |
DISABLED | Y if propagation to destination is disabled, otherwise N |
LAST_TXN_COUNT | Number of transactions pushed last time job ran |
LAST_ERROR | Oracle error number from the most recent push |
LAST_MSG | Error message text from the most recent push |
Column Name | Description |
|---|---|
DEFERRED_TRAN_ID | ID of the transaction that originated or copied the deferred RPCs. |
DEFERRED_TRAN_DB | Global name of the database that originated or copied the deferred RPCs. |
ORIGIN_TRAN_ID | ID of the transaction that originated the deferred RPCs. |
ORIGIN_TRAN_DB | Global name of the database that originated the deferred RPCs. |
ORIGIN_USER | USERID of user originating deferred RPC calls. |
DELIVERY_ORDER | SCN of the deferred transaction in the queue. |
DESTINATION_LIST | R if destinations are determined by the DBA_REPSCHEMA data dictionary view. D if destinations were specified in DEFDEFAULTDEST or the NODE_LIST parameter to the DBMS_DEFER.TRANSACTION, DBMS_DEFER.CALL, or DBMS_DEFER.COPY procedures. |
START_TIME | Start time of the origination transaction. |
COMMIT_COMMENT | User-supplied comments. |
Column Name | Description |
|---|---|
DEFERRED_TRAN_ID | ID of the transaction to propagate to database specified by dblink |
DEFERRED_TRAN_DB | Global name of the database that originated the deferred transaction |
DBLINK |
|  | |
| 16.6 Monitoring Conflict Resolution with DBMS_REPCAT |  | 17.2 DBMS_DEFER_SYS: Managing Deferred Transactions |
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