Oracle GoldenGate Initial Loading: Oracle Database to Oracle Database


For Oracle DB to Oracle DB initial loading, you can use the following approaches:

  • Import/Export with the flashback_scn option and start replication with aftercsn
  • Backup with RMAN and start replciat with atcsn
Different Between SCN and CSN
SCN is used in Oracle Database means SCN (System Change/Commit Number). CSN is used by Oracle GoldenGate means CSN (Checkpoint Sequence Number). They both refer to the same number for Oracle database transactions.

​1. Import/Export with flashback and start replication with AFTERCSN. 
The steps are as follows:​
Step 1. Start the Extract
GGSCI>start extract exext, begin now
Step 2. Check the Current SCN
SQL> select dbms_flashback.get_system_change_number() from dual; (for schema export) 
SQL> select current_scn from v$database ; (for database export)

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Oracle GoldenGate Best Practices: Oracle Migrations and Upgrades 9i and up


Introduction

Eliminating database downtime poses a significant challenge for IT organizations that need to upgrade or migrate mission-critical database environments running Oracle Database 9i or Oracle Database 10g to Oracle Database 11g. This is particularly true for applications that must provide continuous or near-continuous operations to users who increasingly expect uninterrupted availability of online services. Any outage of an application or website, even if that outage is scheduled or planned, has an impact on the revenue and reputation of the business.

For databases that host the data for these mission-critical applications, availability requirements have become stringent. Unfortunately, there are essential events that require application downtime, including modifying hardware or database software, upgrading applications, applying software patches, and migrating to different computing architectures. Because such events are not considered a system or data failure, they are aptly classified as planned outages.

This document explains how organizations can upgrade or migrate from Oracle Database 9i or Oracle Database 10g to Oracle Database 11g with minimum downtime. Using Oracle GoldenGate’s real-time data integration and replication capabilities, businesses can create a clone database to offload instantiation and conversions, keep transactions in sync across the databases, manage partial or phased migrations and upgrades, conduct post upgrade/ migration data verification and implement a reliable failback strategy.

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Oracle Goldengate on DBFS for RAC and Exadata


Let us take a look at the process of configuring Goldengate 12c to work in an Oracle 12c Grid Infrastructure RAC or Exadata environment using DBFS on Linux x86-64.

Simply put the Oracle Database File System (DBFS) is a standard file system interface on top of files and directories that are stored in database tables as LOBs.

In one of my earlier posts we had seen how we can configure Goldengate in an Oracle 11gR2 RAC environment using ACFS as the shared location.

Until recently Exadata did not support using ACFS but ACFS is now supported on version 12.1.0.2 of the RAC Grid Infrastructure.

In this post we will see how the Oracle DBFS (Database File System) will be setup and configured and used as the shared location for some of the key Goldengate files like the trail files and checkpoint files.

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Supplemental logging for Golden Gate


I have submitted my post in another forum where discussion for supplemental logging was going on.

Here is the my reply but I am intending to write a separate blog on Golden Gate.

There are two level of supplemental logging mentioned in oracle documentation

1. Database level supplemental logging
2. Table level supplemental logging

WHY WE NEED SUPPLEMENTAL LOGGING?

One of the main reason to enable supplemental logging is to generate logs for update statement. As insert and delete involves change to whole row (either addition or deletion of complete row) and all columns change in it where as update can happen on a column of a row. Supplemental logging make sure that enough information is captured during this update that can be used by any method based on logminer technology.