Types of Changes for Replication

The sequence values used for individual rows at the databases may vary. Changes to actual sequence values are not captured. For example, if a user references a NEXTVAL or sets the sequence, a Capture process does not capture changes resulting from these operations.

Types of DDL Changes Ignored

A Capture process captures the DDL changes that satisfy its rule sets; however, the following types of DDL changes are never captured. These are very specific to the individual database.

• ALTER DATABASE
   

• CREATE CONTROLFILE
   

• CREATE DATABASE
   

• CREATE PFILE
   

• CREATE SPFILE

This is very important because these above shown SQL statements are database level operations and have no bearing on data rows in the tables. Since the database operations are exclusive and peculiar to that particular database, they are never sent to the destination database, which is a peer system and its own full fledged database system 

A Capture process can capture DDL statements, but not the results of DDL statements, unless the DDL statement is a CREATE TABLE AS SELECT statement. A good example can be seen in an execution of ANALYZE SQL statement on the source database.  When a Capture process captures an ANALYZE statement, it does not capture the statistics generated by the ANALYZE statement. Note that the ANALYZE command writes a considerable amount of information to the data dictionary tables.