Oracle GoldenGate Processes – Part 4 – Replicat

The replicat process is the apply process within the Oracle GoldenGate environment.  The replicat is responsible for reading the remote trail files and applying the data found in cronilogical order.  This ensures that the data is applied in the same order it was captured.  

Until recently there was only one version of a replicat, that version was the classic version.  As of 12.1.2.0, there are now three distinct versions of a replicat.  These replicat types are:

• Classic Mode
• Coordinated Mode
• Integrated Mode

Each of on these modes provide some sort of benefit depending on the database being applied to.  Oracle is pushing everyone to a more integrated approach; however, you have to be on database version 11.2.0.4 at a minimum.  

To configure the replicat process is similar to the extract and data pump processes.

Adding a Replicat:

From GGSCI (classic):

$ cd $OGG_HOME
$ ./ggsci
GGSCI> add replicat REP, exttrail ./dirdat/rt

Note:  The add command is assuming that you already have a checkpoint table configured in the target environment.

Edit Replicat parameter file:

From GGSCI:

$ cd $OGG_HOME
$ ./ggsci
GGSCI> edit params REP

From Command Line:

$ cd $OGG_HOME
$ cd ./dirprm
$ vi REP.prm

Example of Replicat Parameter file:

REPLICAT REP
SETENV (ORACLE_HOME=”/u01/app/oracle/product/11.2.0/db_3″)
SETENV (ORACLE_SID=”orcl”)
USERID ggate, PASSWORD ggate
ASSUMETARGETDEFS
DISCARDFILE ./dirrpt/REP.dsc, append, megabytes 500
WILDCARDRESOLVE IMMEDIATE
MAP SCOTT.*, TARGET SCOTT.*;

Start the Replicat process:

Depending on if you are starting the replicat for the first time or not; how you start is going to be similar yet different.

To star the Replicat after an inital load:

$ cd $OGG_HOME
$ ./ggsci
GGSCI> start replicat REP, atcsn [ current_scn ]

Note: The current_scn needs be obtained from the source database prior to doing the inital load of data to the target.  This ensure the consistancy of the data and provides a starting point for the replicat to start applying data from.

To start Replicat normally:

$ cd $OGG_HOME
$ ./ggsci
GGSCI> start replicat REP

Stop the Replicat process:

Stop replicat normally:

$ cd $OGG_HOME
$ ./ggsci
GGSCI> stop replicat REP

Enjoy!

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