Oracle Essentials Oracle Database 11g by Rick Greenwald Read Free Book Online Page A

complete the distributed transactions.
    Distributed Database Features
    |
    17

    Distributed transactions can also be implemented using popular transaction monitors (TPs) that interact with Oracle via XA, an industry-standard (X/Open) interface.
    Oracle8 i added native transaction coordination with the Microsoft Transaction Server (MTS), so you can implement a distributed transaction initiated under the control of MTS through an Oracle database.
    Heterogeneous Services
    Heterogeneous Services allow non-Oracle data and services to be accessed from an Oracle database through generic connectivity via ODBC and OLE-DB included with the database.
    Optional Transparent Gateways use agents specifically tailored for a variety of target systems. Transparent Gateways allow users to submit Oracle SQL statements to a non-Oracle distributed database source and have them automatically translated into the SQL dialect of the non-Oracle source system, which remains transparent to the user. In addition to providing underlying SQL services, Heterogeneous Services provide transaction services utilizing Oracle’s two-phase commit with non-Oracle databases and procedural services that call third-generation language routines on non-Oracle systems. Users interact with the Oracle database as if all objects are stored in the Oracle database, and Heterogeneous Services handle the transparent interaction with the foreign database on the user’s behalf.
    Data Movement Features
    Moving data from one Oracle database to another is often a requirement when using distributed databases, or when a user wants to implement multiple copies of the same database in multiple locations to reduce network traffic or increase data availability. Youcan export data and data dictionaries (metadata) from one database and import them into another. Oracle Database 10 g introduced a high-speed data pump for the import and export.
    Oracle also offers many other advanced features in this category, including transportable tablespaces, Advanced Queuing/Oracle Streams, and extraction, transformation and loading (ETL) solutions. We introduce these next.
    Transportable Tablespaces
    Transportable tablespaces first appeared in Oracle8 i . Instead of using the export/
    import process, which dumps data and the structures that contain it into an intermediate file for loading, youcan place a tablespace in read-only mode, move or copy it from one database to another, and then mount it. The same data dictionary (metadata) describing the tablespace must exist on the source and the target. This feature can save a lot of time since it simplifies the movement of large amounts of data.
    18
    |
    Chapter 1: Introducing Oracle

    Starting with Oracle Database 10 g , youcan move data with transportable tablespaces between heterogeneous platforms or operating systems.
    Advanced Queuing and Oracle Streams
    Advanced Queuing (AQ), first introduced in Oracle8, provides the means to asynchronously send messages from one Oracle database to another. Because messages are stored in a queue in the database and sent asynchronously when a connection is made, the amount of overhead and network traffic is much lower than it would be using traditional guaranteed delivery through the two-phase commit protocol between source and target. By storing the messages in the database, AQ provides a solution with greater recoverability than other queuing solutions that store messages in filesystems.
    Oracle messaging adds the capability to develop and deploy a content - based publish and subscribe solution using a rules engine to determine relevant subscribing applications. As new content is published to a subscriber list, the rules on the list determine which subscribers should receive the content. This approach means that a single list can efficiently serve the needs of different subscriber communities. In the first release of Oracle9 i , AQ added XML support and Oracle Internet Directory (OID) integration.
    As of the second