Goldengate: Supplemental Logging

In order to configure and install goldengate we have to enable Minimum Supplemental logging at database level. Supplemental logging can be enabled at database level and from ggsci( goldengate command line utility). supplemental logging is of two types for primary key columns (minimal logging) and identify columns need to be logged on oracle database

How to add supplemental logging for table?
Depend on application functionality and keys on tables supplemental logging can be vary for one table to another table. when we enable supplemental logging at table level, along with changed column, primary key columns will be logged into online redo logs. Extract will collect the changes, along with primary key and writes to local trails. using this transaction info logged on the trail, replicat can make consistent SQL using primary key columns and updates target table. 

perform dblogin from goldengate command line utility and add  supplemental logging as follows 
example: 
schema: universe
table:india 

ggsci> dblogin userid ggsuser, password oracle
ggsci> add trandata universe.india 

we can supplemental logging from goldengate command line utility as follows
ggsci> info trandata universe.india 

The GoldenGate ADD TRANDATA command is equivalent to the following SQL statement
SQL> alter table Emp add supplemental log group GGS_EMP ([COLUMN_LIST]) always;

COLUMN_LIST is either the primary key columns or unique index columns, or if there is no primary key or unique index, it will be all columns

checking supplemental logging info for a table involved in goldengate replication:

checking supplemental log groups at table level 

Select log_group_name, table_name, decode (always,'always', 'Unconditional',NULL, 'Conditional') always from DBA_LOG_GROUPS where table_name='EMP';

conditional : If any one of the column is updated in the conditional group before images of all the columns will be logged in the online redo 

unconditional :  Any time the row is updated, unconditional group column will be logged into online redo(before image are logged in the online redo) 

checking supplemental log group columns at table level 

select * from dba_log_group_columns where table_name='EMP';

--NOTE:
Make sure Minimum supplemental logging, force Logging and table level supplemental logging should be enabled for OGG to work good

---Nikhil Tatineni---
---Oracle In-Memory---