Databases Reference
In-Depth Information
consistency, isolation, and durability (ACID) properties as transactions are moved be‐
tween systems and ensures data consistency and referential integrity across multiple
masters, backup systems, and reporting databases.
GoldenGate can be deployed in a variety of scenarios in addition to replication among
transactional databases. As part of a data warehouse infrastructure, it can be integrated
with Oracle Data Integrator Enterprise Edition for ETL and changed data can target
staging tables.
Key components in Oracle GoldenGate include the Capture mechanism, Trail Files, the
Delivery mechanism, and GoldenGate Manager. “Classic Capture” relies on access to
transaction logs (in the case of Oracle or other databases such as Microsoft SQL Server,
IBM DB2, and Sybase) or APIs (such as with Teradata). This Capture mode supports
checkpoints, enabling restarts from the last good checkpoint. In “Integrated Capture
Mode,” GoldenGate provides integration between GoldenGate Extract and the Oracle
log mining server, enabling data to be received as Logical Change Records (LCRs).
Trail Files consist of changed data in the GoldenGate Universal Data Format. Trail Files
exist on the source and are most often pumped to the target(s) using the GoldenGate
Data Pump capabilities. Most often, data is transported using TCP/IP, though the Java
Message Service (JMS) is also supported. Data can be compressed and encrypted (vari‐
able key length) during transportation.
On the Delivery side, transactional data is applied to the target database(s). This is where
changed data is published to JMS or pushed to ETL tools. Changes can be applied
immediately or on a deferred basis. Bounded recovery is supported.
The GoldenGate Manager provides a command line interface to set GoldenGate pa‐
rameters, the capability to start, stop, and monitor the GoldenGate Capture and Delivery
modules, event and threshold reporting, resource management, and Trail File manage‐
ment. The Management Pack for Oracle GoldenGate provides a monitor and plug-in
for Oracle Enterprise Manager.
Oracle GoldenGate Veridata is an option for GoldenGate and is used to detect data
discrepancies between databases. The databases might include Oracle and non-Oracle
databases such as Teradata and Microsoft SQL Server. Administrators can pick and
choose what data they want to compare between the various databases.
GoldenGate is paired with Data Guard for replication in high availability implementa‐
tions where zero data loss is required. We covered high availability and introduced Data
Guard and this concept in
Chapter 11
.
Global Data Services
Oracle
Global Data Services
(GDS), introduced in Oracle Database 12
c
, are used to
integrate multiple replicated Oracle databases into a common configuration accessed
