Do you want to know what are the most frequently asked questions in Oracle GoldenGate?
This post covers the common questions related to Oracle GoldenGate 12c that we get frequently from the trainees of our Oracle GoldenGate 12c Administration course.
If you are new to Oracle GoldenGate then I highly recommend you to look at Oracle GoldenGate 12c Overview & Components and Oracle GoldenGate 12c Download & Installation
Here are the Queries from Trainees:
Q1: What is extract, replicat?
Ans: Extract: The Extract process is responsible for capturing/extracting the committed data from transaction logs of source database. It always runs on source system.
Once extracted it writes the data on local machine into local trail (if exist) or send the data over TCP/IP network to write to remote trail.
Replicat: The Replicat process is the apply process in the Goldengate configuration.
This process runs at the end point of the data delivery chain on the target database.
This process reads the destination trail files and applies the data changes to the target systems.
Q2: What is the datapump in Goldengate?
Ans: The Pump process which is also known as secondary extract process is optional in the Goldengate setup.
This process reads the data from local trail and send it over TCP/IP network to write over to remote trail on target..
Q3: What are the Goldengate types or 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 source to target in cascaded way or thru intermediate server
Q4: Types of replication in Goldengate.
Ans: Goldengate supports replication of DML and DDL transactions.
DML replication is supported in both unidirectional and bidirectional mode.
DDL replication is supported in unidirectional mode only.
Q4: Difference between classic & integral extract process?
Ans: Classic extract reads data directly from transaction logs of database however integrated extract receives data from logminer server and writes to local trails.
Moreover, Integrated extract is only supported for Oracle Databases.
For more info, Refer our blog
GoldenGate: Upgrade Classic Capture to Integrated Capture
Q5: What is the difference between local trail / Remote Trail?
Ans: Local trail written by primary extract is local to source database and resides on source server.
Remote trails are remote to source database and resides on target server which receives data over TCP/IP network from data pump.
Q6: How to start/stop, extract/replicat for source & target?
Ans:The method to start/stop the process remains same as depicted below:
GGSCi> Start|STOP EXTRACT|REPLICAT <process name>
Q7: What is the format for trail file?
Ans: By default Oracle GoldenGate will write the trail files in it’s own Canonical Format. But other than this default format, we can make the Extract Process to write the Trail files in the below formats which is offered by Oracle GoldenGate itself.,
ASCII
SQL
XML
Q8: What is GLOBAL file in Goldengate & location?
Refer: GLOBALS file reside inside dirprm directory. GLOBALS is a parameter file. The parameters specified in GLOBALS file are global and applicable to all the processes in that particular instance.
Q9: What are the directory in Goldengate?
Ans: Goldengate directories are created during installation of goldengate. The directories are responsible for holding the trail files,checkpoint files,definition files,report files,process status files etc.
Q10: What is credential store?
Ans: Credential store by default resides inside dircrd directory under Goldengate home. The credential store manages user IDs and their encrypted passwords (together known as credentials ) that are used by Oracle GoldenGate processes to interact with the local database. The credential store eliminates the need to specify user names and clear-text passwords in the Oracle GoldenGate parameter files.
For more GoldenGate 12c questions and answers check our previous post: FAQ’s: Oracle GoldenGate 12c
If you wish to learn GoldenGate systematically then look at Activity Guides (tasks) you must perform from our Step by Step Guide to Learn Oracle GoldenGate or if you are already working/using Oracle GoldenGate then look at Oracle GoldenGate 12c Troubleshooting using Logdump Utility
This post is from our Oracle GoldenGate 12c Administration Training, in which we cover Architecture, Installation, Configuring & Preparing the Environment, DML Replication – Online Change Synchronization, Initial Load, Zero Downtime Migration & Upgrading using GoldenGate, Oracle GoldenGate Security, Performance of Oracle GoldenGate and Troubleshooting and much more.
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