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Oracle Golden Gate -Concepts and Mechanisms (ogg)

Golden Gate (OGG) provides real-time capture, transformation and delivery of transaction data in heterogeneous environments.

OGG supports heterogeneous environments such as:

Features of OGG:

Small impact on production system: read transaction log in real time, realize real-time replication of large transaction volume data with low resource occupation, and replicate in transaction unit.

Guaranteed transaction consistency:

Sync only submitted data

High performance:

Intelligent transaction restructuring and operational consolidation

Access using database native interfaces

parallel processing architecture

Flexible topology:

Support one-to-one, one-to-many, many-to-one, many-to-many and bidirectional replication

Support data filtering and conversion

You can customize filtering rules based on tables and rows.

Flexible mapping and transformation can be performed on real-time data.

Provides data compression and encryption:

Reduce the bandwidth required for transmission and improve transmission security.

How OGG works:

OGG process:

The Manager process is the control process of GoldenGate, running on both the source and destination sides. Its main functions are as follows: starting, monitoring, restarting other processes of Goldengate, reporting errors and events, allocating data storage space, publishing threshold reports, etc. There is one and only one manager process on both the target and source sides.

Extract runs on the source side of the database and is responsible for capturing data from source-side tables or logs.

The role of Extract can be divided into stages:

An initial time loading phase: In the initial data loading phase, the Extract process extracts data directly from the data table at the source.

Second, synchronization change capture phase: After the initial data synchronization is completed, the Extract process is responsible for capturing changes in the source data (DML and DDL).

The Data Pump process runs on the source side of the database, and its role is to send the local trail file generated by the source side to the target side in the form of data blocks through TCP/IP protocol, which is usually recommended. The pump process is essentially a special form of the extract process. If the trail file is not used, the extract process will deliver the data directly to the target after extracting the data and generate a remote trail file.

The Collector process corresponds to the Data Pump process called the Server Collector process. This process does not need to attract my attention, because in the actual operation process, we do not need to configure it, so it is transparent to us. It runs on the target side and its task is to reassemble the data delivered by Extract/Pump into a remote trail file.

Replicat process, usually also called application process. It runs on the target side and is the last stop of data transfer. It is responsible for reading the contents of the target trail file, parsing it into DML or DDL statements, and then applying them to the target database.

Trail files for OGG:

In order to deliver database transaction information from source to target more efficiently and securely. GoldenGate introduces the concept of trail files. As mentioned earlier, after extract extracts the data, Goldengate converts the extracted transaction information into a file in GoldGate proprietary format. Pump is then responsible for delivering the trail file from the source to the destination, so there will be such files on both sides of the source and destination.

The trail file exists to prevent single points of failure, to persist transaction information, and to use a checkpoint mechanism to record where it is read or written, so that if a failure occurs, the data can be retransmitted according to the location recorded by the checkpoint.

Oracle Golden Gate software is log-based structured data replication backup software that synchronizes source and target databases by parsing source online logs or archive logs for incremental changes in data and applying those changes to the target database. Oracle Golden Gate enables real-time replication of large amounts of data at sub-second level between heterogeneous IT infrastructures (including almost all common operating system platforms and database platforms), so that it can be applied in multiple scenarios such as emergency systems, online reporting, real-time data warehouse provisioning, transaction tracking, data synchronization, centralization/distribution, disaster recovery, database upgrade and migration, and dual service centers. At the same time, Oracle Golden Gate can implement one-to-one, broadcast (one-to-many), aggregation (many-to-one), bidirectional, point-to-point, cascade and other flexible topologies.

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