What are prerequisites for creating a logical standby database?

Hi ,

Prior to creating the Logical Standby please ensure the following:

1) Determine if the primary database contains datatypes or tables that are not
supported by a logical standby database.

SQL> select distinct owner,table_name from dba_logstdby_unsupported order by owner,table_name;

to view the column names and datatypes for one of the tables listed in previous query.

SQL> select column_name,data_type from dba_logstdby_unsupported where owner=’ ‘ and table_name=’
‘;

2) Ensure that table rows in the primary database can be uniquely identified.

to find the tables which do not have unique key use the following query.

SQL> select owner,table_name,bad_column from dba_logstdby_not_unique where table_name not in ( select table_name from dba_logstdby_unsupported);

3) Ensure that the primary database is in ARCHIVELOG mode and that archiving is enabled.

4. Ensure supplemental logging is enabled on the primary database. To see if supplemental logging is enabled, start a SQL session and query the
V$DATABASE fixed view.

For example, enter:

SQL> SELECT SUPPLEMENTAL_LOG_DATA_PK, SUPPLEMENTAL_LOG_DATA_UI FROM V$DATABASE;

SUP SUP
— —
YES YES

If supplemental logging is not enabled, execute the following statements:

SQL> ALTER DATABASE ADD SUPPLEMENTAL LOG DATA (PRIMARY KEY, UNIQUE INDEX) COLUMNS;

SQL> ALTER SYSTEM SWITCH LOGFILE;

5. Ensure LOG_PARALLELISM init.ora parameter is set to 1 (default value).