Oracle 在2009年收購了Golden Gate，之后Oracle 把Stream 的一些優(yōu)點(diǎn)引入到了Golden Gate。 所以以后在數(shù)據(jù)復(fù)制這塊，Oracle 肯定也是大力發(fā)展Golden Gate。
官網(wǎng)參考：
http://www.oracle.com/us/corporate/Acquisitions/goldengate/index.html
Golden Gate復(fù)制原理是通過挖掘Oracle的日志（redo和歸檔），然后生成自己的隊列文件，通過隊列文件傳輸?shù)侥繕?biāo)端，目標(biāo)端通過讀取相應(yīng)的隊列文件在目標(biāo)數(shù)據(jù)庫中重演事務(wù)。
Golden Gate 可以跨不同的數(shù)據(jù)庫進(jìn)行復(fù)制，如Oracle、IBM DB2、MS SQL Server等。Quest 公司也有一個復(fù)制軟件：SharePlex，不過它只支持Oracle到Oracle的復(fù)制。用過Toad 的人應(yīng)該都知道Quest 公司。
在聯(lián)機(jī)文檔上找了點(diǎn)這塊的資料，粘貼如下，有空在研究下Golden Gate.
Oracle Database High Availability Solutions for Unplanned Downtime
http://download.oracle.com/docs/cd/E11882_01/server.112/e17157/unplanned.htm#HAOVW121
3.7 Oracle GoldenGate and Oracle Streams
Oracle GoldenGate is Oracle's strategic product for data distribution and data integration. It is a high-performance software application that uses log-based bidirectional data replication for real-time capture, transformation, routing, and delivery of database transactions across heterogeneous systems.（GG 說明）Oracle GoldenGate helps you achieve continuous availability and real-time integration for your mission-critical data. It is described in more detail in Section 3.7.1.
Oracle Streams is also a very flexible and powerful database replication feature that Oracle will continue to support but will not make major enhancements in future releases.(Oracle 在Stream 上不會在投入太多了) You can continue to use an existing Oracle Streams deployment to maximize your return on investment. However, you should consider Oracle GoldenGate as the long-term replication strategy for your organization. See the Oracle Database 2 Day + Data Replication and Integration Guide, Oracle Streams Concepts and Administration, and the Oracle Streams Replication Administrator's Guide for more information about Oracle Streams data replication and integration.
Oracle GoldenGate will be enhanced with many of the best capabilities of Oracle Streams to create a best-of-both worlds information distribution solution.
3.7.1 About Oracle GoldenGate
Oracle GoldenGate is an asynchronous, log-based, real-time data replication product that moves high volumes of transactional data in real-time across heterogeneous database, hardware, and operating system environments with minimal impact.
A typical environment includes a capture, pump and delivery process. Each of these processes can run on most of the popular operating systems and databases, including Oracle Database and non-Oracle databases. All or a portion of the data may be replicated, and the data within any of these processes may be manipulated for not only heterogeneous environments but also different database schemas. Oracle GoldenGate supports multimaster replication, hub-and-spoke deployment, and data transformation. Thus, Oracle GoldenGate enables you to ensure that your critical systems are operational 24/7, and the associated data is distributed across the enterprise to optimize decision making.
Oracle GoldenGate is also an excellent method to minimize downtime during planned maintenance, including application and database upgrades, in addition to platform migrations.
Benefits of Oracle GoldenGate
Oracle GoldenGate optimizes real-time information access and availability because it:
（1）Supports replication involving a heterogeneous mix of Oracle Database and non-Oracle databases
（2）Maintains continuous availability to mission-critical systems:
1）Disaster recovery and data protection
Creates and maintains an immediate failover site with up-to-the-minute data to minimize recovery time for mission-critical systems.
2）Zero downtime operations
Enables uninterrupted business operations during system upgrades, migration, and maintenance activities.
3）Data distribution
Synchronizes data for distributed applications in real time for improved availability and scalability.
4）Query offloading
Ensures high performance for production systems while still supporting necessary read-only activities by replicating data between heterogeneous sources and targets.
（3）Enables real-time data integration across the enterprise:
1）Real-time data warehousing
Provides continuous, real-time capture and delivery of the most recent change data between OLTP systems and the data warehouse.
2）Operational reporting
Off loads reporting activity from the production database to lower-cost secondary systems that have current data for real-time reporting.
3）Operational data integration
Integrates operational data between OLTP systems in real time.
3.7.2 Using Oracle GoldenGate with Oracle Active Data Guard
Oracle Golden Gate and Oracle Active Data GuardFoot 2 are strategic capabilities within Oracle's software portfolio and are complementary to each other. When used together, Oracle GoldenGate and Oracle Active Data Guard offer a unique data protection and information distribution solution not offered by any other product.
While these features generally fall into the category of replication technologies, each has a very different area of focus:
（1）Oracle Active Data Guard is Oracle's strategic product for data protection and disaster recovery for Oracle Database.
Oracle Active Data Guard is a superset of standard Data Guard functionality included in Oracle Database Enterprise Edition, thus Active Data Guard also inherits all Data Guard functionality:
1) Transparent operation across all data types, storage attributes, DML and DDL
2) Management simplicity; simple one-way replication of the entire database
3) Superior corruption protection
4) Choice of asynchronous or synchronous (zero data loss) protection
5) High availability during unplanned events via automatic database and client failover
6) Minimized downtime by implementing database upgrades, system and site maintenance, or technology refresh, in rolling fashion across primary and standby databases
Oracle Active Data Guard requires a separate license and can only be used with Oracle Database Enterprise Edition. It can be purchased as the Active Data Guard Option for Oracle Database Enterprise Edition. It is also included with Oracle GoldenGate. Basic Data Guard functionality does not require a separate license, and it is included with Oracle Enterprise Edition. Oracle Active Data Guard is described in Section 3.6.2.
（2）Oracle GoldenGate is Oracle's strategic product for data distribution and data integration.
Oracle GoldenGate supplements Active Data Guard with its heterogeneous and bidirectional replication capabilities to enable enterprise-wide information distribution, zero-downtime upgrades and migrations, query offloading to heterogeneous systems, and multimaster database solutions.
Depending on the business situation:
1）Choose Oracle Active Data Guard for a simple, high-performance, drop-in solution for disaster recovery, data protection, and high availability for the entire Oracle database.
2）Choose Oracle GoldenGate to set up a data distribution and data synchronization solution through this Oracle-Oracle replication configuration, or a more flexible multimaster HA solution.
Figure 3-1 shows a configuration in which an Oracle Data Guard physical standby database provides optimal data protection and offloads read-only workload from the primary database. It also provides for heterogeneous replication of various subsets of the production database to multiple target databases. Rather than host Oracle GoldenGate replication on the production database, the Oracle GoldenGate capture process is offloaded to the physical standby database where changes are captured from archived redo logs and replicated, without necessitating overhead for Oracle GoldenGate processing on the production system.
Figure 3-1 Oracle GoldenGate and Oracle Data Guard for Unplanned Outages
Description of "Figure 3-1 Oracle GoldenGate and Oracle Data Guard for Unplanned Outages"
Oracle GoldenGate is also an excellent method to minimize downtime during planned maintenance, including application and database upgrades and platform migrations.
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