Difference Between Oracle Goldengate & Oracle Dataguard

Difference Between Oracle Goldengate & Oracle Dataguard

Oracle GoldenGate Basics

Oracle GoldenGate Basics

What is Oracle GoldenGate ?

Oracle Golden Gate is a software product that allows you to replicate, filter, and transform data from one database to another database.

What You Can do By using Oracle GoldenGate ?

-> Using Oracle Golden Gate, you can move committed transactions across multiple heterogeneous systems in your enterprise.
-> It enables you to replicate data between Oracle databases to other supported heterogeneous database, and between heterogeneous databases.
-> You can replicate to Java Messaging Queues, Flat Files, and to Big Data targets in combination with Oracle Golden Gate for Big Data.

Oracle GoldenGate Purposes ?

-> A static extraction of data records from one database and the loading of those records to another database.
-> Continuous extraction and replication of transactional Data Manipulation Language (DML) operations and data definition language (DDL) changes (for supported databases) to keep source and target data consistent.
-> Extraction from a database and replication to a file outside the database.

Oracle GoldenGate Key Features

-> Data movement is in real-time, reducing latency.
-> Only committed transactions are moved, enabling consistency and improving performance.
-> Different versions and releases of Oracle Database are supported along with a wide range of heterogeneous databases running on a variety of operating systems.
-> You can replicate data from an Oracle Database to a different heterogeneous database.
-> Simple architecture and easy configuration.
-> High performance with minimal overhead on the underlying databases and infrastructure.

GoldenGate supported Heterogeneous Environments ?

-> Different platforms (Linux, Windows, etc.)
-> Different databases (Oracle, MySQL, SQLServer, etc.)
-> Different database versions

Oracle GoldenGate Components

-> Extract
-> Data pump
-> Replicat
-> Trails or extract files
-> Checkpoints
-> Manager
-> Collector

Oracle GoldenGate Logical Architecture ?

When Do You Use Oracle GoldenGate ?

The most common use cases are
-> Business continuity and high availability
-> Initial load and database migration and upgrades with zero downtime
-> Data integration
-> Decision support and data warehousing.

How Do You Use Oracle GoldenGate ?

There are many different architectures that can be configured; which range from a simple uni-directional architecture to the more complex peer-to-peer. No matter the architecture, Oracle GoldenGate provides similarities between them, making administration easier.

Oracle Golden Gate Supported Topologies ?

Oracle Goldengate Interview Questions & Answers

Oracle Goldengate Interview Questions & Answers

Q. What database does GoldenGate support for replication?

-Oracle Database
-TimesTen
-MySQL
-IBM DB2
-Microsoft SQL Server
-Informix
-Teradata
-Sybase
-Enscribe
-SQL/MX
-NOSQL
-INFORMIX

Q. What transaction types does GoldenGate support for Replication?

GoldenGate supports both DML and DDL Replication from the source to target. DDL and DML could be enabled separately without enabling the other transaction types.

Q. What are the GoldenGate setup pre-requisites?

Source:
The following supplemental logging is required. -
Database supplemental logging
Object level supplemental logging (ADD TRANDATA)
Database level GoldenGate user with GoldenGate level privileges for extraction of data from
source database.
Target:
Database level GoldenGate user with GoldenGate level privileges for replication of data to target
database.

Q. Why is Supplemental logging required for Replication?

When a transaction is committed on the source database, only new data is written to the Redo
log. However for Oracle to apply these transactions on the destination database, the before image
key values are required to identify the effected rows. This data is also placed in the trail file and
used to identify the rows on the destination, using the key value the transactions are executed
against them. So to say in few words, to uniquely identify the row Supplemental logging is required.

Q. Why are the Parameter files in GoldenGate?

Parameter files are heartbeat of GoldenGate. GoldenGate process works based on Parameters defined in Parameter files. Every Process in GoldenGate has its own Parameter file.

Q. What is the location of Report files?

The report file for each process is written inside dirrpt. GoldenGate stored 10 latest report file for each process in dirrpt.

Q. Which Parameter id used to housekeep the trail Files of GoldenGate?

PURGEOLDEXTRACTS is used in manager parameter file to housekeep the trail files.

Q. I want to view description regarding a particular Parameter. Is there any parameter in GoldenGate?

From 12.2 onwards u can use parameter INFO PARAM <PARAMETER NAME> in GGSCI.
GGSCI> info param<PARAMETER NAME>

Q. What is data pump process in GoldenGate?

The Data Pump (not to be confused with the Oracle Export Import Data Pump) is an optional secondary Extract group that is created on the source system. When Data Pump is not used, the Extract process writes to a remote trail that is located on the target system using TCP/IP. When Data Pump is configured, the Extract process writes to a local trail and from here Data Pump will read the trail and write the data over the network to the remote trail located on the target system. The advantages of this be it protects against a network failure as in the absence of a storage device on the local system, the Extract process writes data into memory before the same is sent over the network. Any failures in the network could then cause the Extract process to abort (abend). Also, if we are doing any complex data transformation or filtering, the same can be performed by the Data Pump. It will also be useful when we are consolidating data from several sources into one central target where data pump on each individual source system can write to one common trail file on the target.

Q. Where can filtering of data for a column be configured?

Filtering of the columns of a table can be set at the Extract, Pump or Replicat level.

Q. Is it a requirement to configure a PUMP extract process in OGG replication?

PUMP extract is an option, but it is highly recommended to use this to safe guard against network failures. Normally it is configured when you are setting up OGG replication across the network.

Q. List the minimum parameters that can be used to create the extract process?

The following are the minimum required parameters which must be defined in the extract
parameter file.
EXTRACT NAME
USERID
EXTTRAIL
TABLE

Q. What is the command line utility in GoldenGate (or) what is ggsci?

GoldenGate Command Line Interface essential commands – GGSCI
GGSCI — (Oracle) GoldenGate Software Command Interpreter

Q. What type of Encryption is supported in GoldenGate?

Oracle GoldenGate provides 3 types of Encryption.

-Data Encryption using Blow fish.
-Password Encryption in dircrd
-Network Encryption.

Q. What are the different password encryption options available with OGG?
You can encrypt a password in OGG using Blowfish algorithm and Advance Encryption Standard (AES) algorithm

Q. Is there a way to check the syntax of the commands in the parameter file without running the GoldenGate process?

Yes, you can place the SHOWSYNTAX parameter in the parameter file and try starting. If there is any error, you will see it.

Q. What information can you expect when there us data in the discard file?

When data is discarded, the discard file can contain:
Discard row details
Database Errors
Trail file number

Q. What command can be used to switch writing the trail data to a new trail file?

You can use the following command to write the trail data to a new trail file.
SEND EXTRACT ext_name, ROLLOVER

Q. How can you determine if the parameters for a process was recently changed?
Whenever a process is started, the parameters in the.prm file for the process is written to the process REPORT. You can look at the older process reports to view the parameters which were used to start up the process. By comparing the older and the current reports you can identify the changes in the parameters.

Oracle GoldenGate Processes & Status

Oracle GoldenGate Processes & Status

Manager Process
-Manager process is common for source and target datatabase.
-It is required for Stop and Start GoldenGate Extract, Pump and Replicat processes
-It will monitor the livileness of other processes within the system.
-Default port is 7809
-It is the actual process which control other sub-components.
-It makes the communication using GG user.

Status of manager process:
-Stopped
-Running

Extract Process
-This is the actual process on source side which reads the actual data.
-It reads database from online redo log files and optionally from archive log files and write data to local or remote trail files.

Status of extract process:
-Stopped
-Starting
-Running
-Abended

Pump Process
-It is optional process avaliable on source side.
-To reduce the load of extract process.
-It reads data from local trail file and writes data to remote trail over the TCP/IP network. It is an optional process but highly recommended.

Status of pump process:
-Stopped
-Starting
-Running
-Abended

Replicat Process
-This is the actual process which available on target and it is actually apply the data to the database.
-It reads data from remote trail files and write to the database one transaction at a time.

Status of replicat process:
-Stopped
-Starting
-Running
-Abended

Collector Process
-This process is only available on target side.
-It receives data from Pump Extract and writes data to remote trail files.

Trails and Files
- Trail files ar the files which actually contains the data in the source and target side.
-Trails files are required for continuous data replication. These files are canonical structured files which only GoldenGate process can read.

Checkpoint Table
-CKPT is to maintain the integrity of data on the soure and target system.
-Incase of failure it doesn't read from the scratch, it reads from the point-of-failure.
-It provides the transaction recovery in case GoldenGate processes stopped abnormally.

Wallet
-It is a secure common storage for User IDs and Passwords. It is highly recommended to use wallet for secure credentials

Oralce Goldengate Topologies

Oralce Goldengate Topologies

• Uni-directional: Data is replicated in one direction from source to target.
• Bi-Directional: The data flows in both direction and stays synced up between site A and site B.
• Peer to Peer: Similar to Bi-directional but involves more that 2 databases which stay synced up.
• Broadcast: Data from source is sent to multiple destinations.
• Consolidation: Data from multiple sources is delivered to one destination DB.
• Cascading: Data from one source is sent to multiple destinations.

Oracle GoldenGate Key Features and Benefits

Oracle GoldenGate Key Features and Benefits

Oracle GoldenGate provides the following features and benefits that enable you to rapidly move transactional data between enterprise systems, Maintain Continuous Availability to Critical Systems and Oracle GoldenGate helps organizations eliminate the downtime caused by both unplanned and planned outages, and improve system performance and scalability.

The software can be configured to support the following scenarios:

-Disaster recovery and data protection. Create and maintain an immediate failover with up-to-the-minute data to minimize recovery time for missioncritical systems—deploy with Oracle Database or in non-Oracle environments.

-Zero-downtime operations. Enable uninterrupted business operations during system upgrade, migration, and maintenance activities.

-Data distribution. Synchronize data for distributed applications in real time for improved availability and scalability.

-Query offloading. Ensure high performance for production systems while still supporting necessary read-only activities by replicating data between heterogeneous sources and targets.

-Real-time data: Immediately capture, transform, and deliver transactional data to other systems with subsecond latency. Improve organizational decision-making through enterprise-wide visibility into accurate, up-to-date information.

-Heterogeneous support: Utilize heterogeneous databases and platforms to increase IT department flexibility. Extract data from existing IT investments and lower your total cost of ownership while unifying data from all enterprise systems

-Reliability: Deliver all committed records to the target, even in the event of network outages. Move data without requiring system interruption or outage windows.

-High performance with low impact: Move thousands of transactions per second with negligible impact on source and target systems. Access critical information in real time without bogging down production systems.

-Flexible topology support: Manage data in one-source-to-one-target, one-to-many, many-to-one, many-to-many, cascading, and bidirectional configurations.

Oracle Goldengate Faq's

Oracle Goldengate Faq's

Question: What is a checkpoint table?

Answer: A checkpoint table is a small table in the target database used by the Replicat process to maintain checkpoints. A checkpoint records a known position in the trail from which to start after an expected or unexpected shutdown. By default, a record of these checkpoints is maintained in a file on disk in the GoldenGate directory. Optionally, the checkpoint record can also be maintained in a checkpoint table in the target database.

Question: Why should I use a checkpoint table?

Answer: Using a checkpoint table (database checkpointing) is recommended because it enables the checkpoint to be included within Replicat's transaction, which improves recovery in certain situations. If you elect not to use a checkpoint table, data integrity will still be maintained by means of the checkpoint file on disk, although there may be correctable database errors in those circumstances that otherwise would be handled by means of database checkpointing.

Question: How large will the checkpoint table get?

Answer: The checkpoint table should remain small because rows are deleted when no longer needed, and it will not affect database performance.

Question: Does it matter where I create this table?

Answer: The checkpoint table can reside in a schema of your choice, but GoldenGate recommends using one that is dedicated to GoldenGate.

Question: Do I need a checkpoint table for each Replicat or each instance of GoldenGate on a system?

Answer: No. You only need to create one checkpoint table for all GoldenGate installations and Replicat groups. GoldenGate keeps track of the checkpoints, even if Replicat group names are the same in different instances.

Question: Could I use different checkpoint tables for different groups if I want?

Answer: Yes. Use as many as you like to customize database checkpointing to your needs. If you like, you can specify a default checkpoint table (recommended) and also specify overrides to the default as needed. When you use a default checkpoint table, you do not have to remember its name or specify it whenever you add new Replicat groups.