Schema level and table level supplemental logging

Question

Hello,
I'm setting up bi- directional DML replication between two oracle databases. I have enabled supplemental logging database level by running this command-
SQL>alter database add supplemental log data (primary key) columns;
Database altered.
SQL> select SUPPLEMENTAL_LOG_DATA_MIN, SUPPLEMENTAL_LOG_DATA_PK, SUPPLEMENTAL_LOG_DATA_UI from v$database;
SUPPLEME SUP SUP
IMPLICIT YES NO
-My question is should I enable supplemental logging table level also(for DML replication only)? should I run the below command also?
GGSCI (db1) 1> DBLOGIN USERID ggs_admin, PASSWORD ggs_admin
Successfully logged into database.
GGSCI (db1) 2> ADD TRANDATA schema.<table-name>
what is the deference between schema level and table level supplemental logging?

Answer 1

For Oracle, ADD TRANDATA by default enables table-level supplemental logging. The supplemental log group includes one of the following sets of columns, in the listed order of priority, depending on what is defined on the table:
1. Primary key
2. First unique key alphanumerically with no virtual columns, no UDTs, no functionbased
columns, and no nullable columns
3. First unique key alphanumerically with no virtual columns, no UDTs, or no functionbased
columns, but can include nullable columns
4. If none of the preceding key types exist (even though there might be other types of keys
defined on the table) Oracle GoldenGate constructs a pseudo key of all columns that
the database allows to be used in a unique key, excluding virtual columns, UDTs,
function-based columns, and any columns that are explicitly excluded from the Oracle
GoldenGate configuration.
The command issues an ALTER TABLE command with an ADD SUPPLEMENTAL LOG DATA clause that
is appropriate for the type of unique constraint (or lack of one) that is defined for the table.
When to use ADD TRANDATA for an Oracle source database
Use ADD TRANDATA only if you are not using the Oracle GoldenGate DDL replication feature.
If you are using the Oracle GoldenGate DDL replication feature, use the ADD SCHEMATRANDATA command to log the required supplemental data. It is possible to use ADD
TRANDATA when DDL support is enabled, but only if you can guarantee one of the following:
● You can stop DML activity on any and all tables before users or applications perform DDL on them.
● You cannot stop DML activity before the DDL occurs, but you can guarantee that:
❍ There is no possibility that users or applications will issue DDL that adds new tables whose names satisfy an explicit or wildcarded specification in a TABLE or MAP
statement.
❍ There is no possibility that users or applications will issue DDL that changes the key definitions of any tables that are already in the Oracle GoldenGate configuration.
ADD SCHEMATRANDATA ensures replication continuity should DML ever occur on an object for which DDL has just been performed.
You can use ADD TRANDATA even when using ADD SCHEMATRANDATA if you need to use the COLS option to log any non-key columns, such as those needed for FILTER statements and KEYCOLS clauses in the TABLE and MAP parameters.
Additional requirements when using ADD TRANDATA
Besides table-level logging, minimal supplemental logging must be enabled at the database level in order for Oracle GoldenGate to process updates to primary keys and
chained rows. This must be done through the database interface, not through Oracle GoldenGate. You can enable minimal supplemental logging by issuing the following DDL
statement:
SQL> alter database add supplemental log data;
To verify that supplemental logging is enabled at the database level, issue the following statement:
SELECT SUPPLEMENTAL_LOG_DATA_MIN FROM V$DATABASE;
The output of the query must be YES or IMPLICIT. LOG_DATA_MIN must be explicitly set, because it is not enabled automatically when other LOG_DATA options are set.
If you required more details refer Oracle® GoldenGate Windows and UNIX Reference Guide 11g Release 2 (11.2.1.0.0)