SQL/MX Queuing and Publish/Subscribe Services

HP NonStop SQL/MX Queuing and Publish/Subscribe Services—523734-002
2-1
2 Major Queuing Features
The queuing extensions to SQL/MX are special operations defined on regular
database tables. These operations are specified as extensions to the Data
Manipulation Language (DML) and do not introduce any new database objects.
Applications access tables that are defined by the Data Definition Language (DDL).
Publish/subscribe supports only audited tables.
The single most important feature for the queuing and publish/subscribe services is the
stream access mode. Additionally, the queueing and publish/subscribe services are
implemented through the following SQL language extensions and special access
modes.
This section describes:
Stream Access on page 2-2 Allows an application to access SQL/MP or
SQL/MX database tables as continuous data
streams.
Stream Timeout Attribute on
page 2-3
Allows an application to set the time for a fetch
operation that uses stream access to wait for
more rows before timing out.
Embedded DELETE on page 2-3 Allows an application to select and delete rows
in one statement execution.
Embedded UPDATE on page 2-5 Allows an application to select and update rows
in one statement execution.
Skip Conflict Access on page 2-7 Allows an application to skip rows that are
locked by a concurrent transaction.
AFTER LAST ROW on page 2-8 Allows a SELECT statement to skip all existing
rows in the table and return only rows that are
published after the stream's cursor is opened.
Set Column Values On Rollback
on page 2-9
Allows an application to update columns due to
a rollback of a delete or update operation.
Holdable Cursors on page 2-10 Allows an application to retain an open cursor
across transactions.
Rowset Integration on page 2-12 Allows an application to enqueue or dequeue
multiple rows at one time.
Partitioned Queues on page 2-13 Allows an application to distribute data to
balance the load across individual devices in a
cluster.
Ordered Streams on page 2-14 Allows an application to order rows in a data
stream according to user-specified column
values, where the order is enforced by the
clustering key or a secondary index.