Oracle Streams 11g Interview Questions and Answers - 1

Question: 1

What is the difference between Oracle streams and CDC?

Oracle streams are based on advance queues. The streams provide a mechanism to synchronize data between two servers.

Streams ensure reliable data synchronization between the servers based on the defined rules.

Both Oracle CDC and Streams are generally used for data synchronization between Oracle database servers. With Oracle CDC, you could write your own data export routines, which create flat files for the purpose of synchronization between two database servers; whereas, with Streams you must have a network link between the two servers.

Question: 2

What is Streams?

An oracle stream is a data replication and integration feature.

It enables the propagation of data, transactions, and events in a data stream either within a database or from one database to another.

Question: 3

What is Stream replication?

Stream replication uses the information available in redo logs to synchronize data between two servers.

The capture process captures the changes at source, and the changes are transported to the target database, which generates the transactions and the apply process applies those transactions.

Question: 4

What is Change Data Capture?

CDC is a technique to capture changes in database tables. These changes are stored in special tables.

CDC operates in two modes: asynchronous, which is based on Java, and synchronous, which is used on database triggers.

Performance overhead is higher in case of synchronous CDC.

Question: 5

What is the capture process?

Capture process extracts database changes from redo log files at source. It is a background process.