Dequeue Options Type

The dequeue_options_t data structure specifies the options available for the dequeue operation.

Syntax

TYPE dequeue_options_t IS RECORD (
   consumer_name    VARCHAR2(30)   DEFAULT NULL,
   dequeue_mode     BINARY_INTEGER DEFAULT REMOVE,
   navigation       BINARY_INTEGER DEFAULT NEXT_MESSAGE,
   visibility       BINARY_INTEGER DEFAULT ON_COMMIT,
   wait             BINARY_INTEGER DEFAULT FOREVER,
   msgid            RAW(16)        DEFAULT NULL,
   correlation      VARCHAR2(128)  DEFAULT NULL,
   deq_condition    VARCHAR2(4000) DEFAULT NULL,
   transformation   VARCHAR2(60)   DEFAULT NULL );

Attributes

Table 4-6 Dequeue Options Type Attributes

Attribute	Description
consumer_name	Name of the consumer. Only those messages matching the consumer name are accessed. If a queue is not set up for multiple consumers, then this field should be set to NULL.
dequeue_mode	Specifies the locking behavior associated with the dequeue. BROWSE: Read the message without acquiring any lock on the message. This is equivalent to a select statement. LOCKED: Read and obtain a write lock on the message. The lock lasts for the duration of the transaction. This is equivalent to a select for update statement. REMOVE: Read the message and update or delete it. This is the default. The message can be retained in the queue table based on the retention properties. REMOVE_NODATA: Mark the message as updated or deleted. The message can be retained in the queue table based on the retention properties.
navigation	Specifies the position of the message that will be retrieved. First, the position is determined. Second, the search criterion is applied. Finally, the message is retrieved. NEXT_MESSAGE: Retrieve the next message which is available and matches the search criteria. If the previous message belongs to a message group, then AQ retrieves the next available message which matches the search criteria and belongs to the message group. This is the default. NEXT_TRANSACTION: Skip the remainder of the current transaction group (if any) and retrieve the first message of the next transaction group. This option can only be used if message grouping is enabled for the current queue. FIRST_MESSAGE: Retrieves the first message which is available and matches the search criteria. This resets the position to the beginning of the queue.
visibility	Specifies whether the new message is dequeued as part of the current transaction.The visibility parameter is ignored when using the BROWSE mode. ON_COMMIT: The dequeue will be part of the current transaction. This is the default case. IMMEDIATE: The dequeued message is not part of the current transaction. It constitutes a transaction on its own.
wait	Specifies the wait time if there is currently no message available which matches the search criteria. FOREVER: wait forever. This is the default. NO_WAIT: do not wait number: wait time in seconds
msgid	Specifies the message identifier of the message to be dequeued.
correlation	Specifies the correlation identifier of the message to be dequeued. Special pattern matching characters, such as the percent sign (%) and the underscore (_) can be used. If more than one message satisfies the pattern, then the order of dequeuing is undetermined.
deq_condition	A conditional expression based on the message properties, the message data properties and PL/SQL functions. A deq_condition is specified as a Boolean expression using syntax similar to the WHERE clause of a SQL query. This Boolean expression can include conditions on message properties, user data properties (object payloads only), and PL/SQL or SQL functions (as specified in the where clause of a SQL query). Message properties include priority, corrid and other columns in the queue table To specify dequeue conditions on a message payload (object payload), use attributes of the object type in clauses. You must prefix each attribute with tab.user_data as a qualifier to indicate the specific column of the queue table that stores the payload. The deq_condition parameter cannot exceed 4000 characters.
transformation	Specifies a transformation that will be applied after dequeuing the message. The source type of the transformation must match the type of the queue.