PURGE Function

This function purges pushed transactions from the deferred transaction queue at your current master site or materialized view site.

Syntax

DBMS_DEFER_SYS.PURGE (
   purge_method         IN  BINARY_INTEGER := purge_method_quick,
   rollback_segment     IN  VARCHAR2       := NULL,
   startup_seconds      IN  BINARY_INTEGER := 0,
   execution_seconds    IN  BINARY_INTEGER := seconds_infinity,
   delay_seconds        IN  BINARY_INTEGER := 0,
   transaction_count    IN  BINARY_INTEGER := transactions_infinity,
   write_trace          IN  BOOLEAN        := NULL);
  RETURN BINARY_INTEGER;

Parameters

Table 14-18 PURGE Function Parameters

Parameter	Description
purge_method	Controls how to purge the deferred transaction queue: `purge_method_quick` costs less, while `purge_method_precise` offers better precision. Specify the following for this parameter to use `purge_method_quick`: `dbms_defer_sys.purge_method_quick` Specify the following for this parameter to user `purge_method_precise`: `dbms_defer_sys.purge_method_precise` If you use `purge_method_quick`, deferred transactions and deferred procedure calls that have been successfully pushed may remain in the `DEFTRAN` and `DEFCALL` data dictionary views for longer than expected before they are purged. See "Usage Notes" for more information.
rollback_segment	Name of rollback segment to use for the purge, or `NULL` for default.
startup_seconds	Maximum number of seconds to wait for a previous purge of the same deferred transaction queue.
execution_seconds	If > 0, then stop purge cleanly after the specified number of seconds of real time.
delay_seconds	Stop purge cleanly after the deferred transaction queue has no transactions to purge for `delay_seconds`.
transaction_count	If > 0, then shut down cleanly after purging `transaction_count` number of transactions.
write_trace	When set to `true`, Oracle records the result value returned by the `PURGE` function in the server's trace file. When set to `false`, Oracle does not record the result value.

Returns

Table 14-19 Purge Function Returns

Value	Description
result_ok	OK, terminated after `delay_seconds` expired.
result_startup_seconds	Terminated by lock timeout while starting.
result_execution_seconds	Terminated by exceeding `execution_seconds`.
result_transaction_count	Terminated by exceeding `transaction_count`.
result_errors	Terminated after errors.
result_split_del_order_limit	Terminated after failing to acquire the enqueue in exclusive mode. If you receive this return code, then retry the purge. If the problem persists, then contact Oracle Support Services.
result_purge_disabled	Queue purging is disabled internally for synchronization when adding new master sites without quiesce.

Exceptions

Table 14-20 PURGE Function Exceptions

Exception	Description
argoutofrange	Parameter value is out of a valid range.
executiondisabled	Execution of purging is disabled.
defererror	Internal error.

Usage Notes

When you use the purge_method_quick for the purge_method parameter in the DBMS_DEFER_SYS.PURGE function, deferred transactions and deferred procedure calls may remain in the DEFCALL and DEFTRAN data dictionary views after they have been successfully pushed. This behavior occurs in replication environments that have more than one database link and the push is executed to only one database link.

To purge the deferred transactions and deferred procedure calls, perform one of the following actions:

Use purge_method_precise for the purge_method parameter instead of the purge_method_quick. Using purge_method_precise is more expensive, but it ensures that the deferred transactions and procedure calls are purged after they have been successfully pushed.
Using purge_method_quick for the purge_method parameter, push the deferred transactions to all database links. The deferred transactions and deferred procedure calls are purged efficiently when the push to the last database link is successful.