Expert Oracle Exadata - Parent Directory

CHAPTER 13 MIGRATING TO EXADATA• CLOB• NCLOB• NTYThe following is a quick summary of the benefits common to both Oracle Streams and Golden Gate:• Support for failover (Oracle RAC environments)• Support for multi-tenant databases• Support for table partitioning (target tables)• Support for HCC compression (target tables only for Golden Gate) although youmay not get the best loading compression ratio compared to CTAS or IAS• Support for storage changes for tables and indexes (target tables)• Ability to change indexing strategy (target tables)• Read access to the target tables during migration• Support for endian differences between source and target• Support for character set differences between source and target• Support for different database block sizes between source and target• Support for change Capture on the target server, reducing the performanceimpact on the source system• Not difficult to setup• Database version-agnostic• Very little downtime to switch overDisadvantages common to both Streams and Golden Gate:• Replicated tables must be keyed. If there is no primary key on the source table,you must provide a list of columns that provide uniqueness. If no suchcombination exists, the table cannot be replicated.• Some data types are not supported for replication.• Log mining on the source system can impact performance. Consider moving thechange Capture to the target system.• It’s more complex than other migration strategies.Disadvantages of Streams compared to Golden Gate:• Data mining can heavily impact performance on the source database.• It is more complex to set up.• DDL is supported but problematic.446