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An oracle stream is all about information sharing. The stream is used to propagate message within database or to other data base. Oracle steams can be easily set up in the homogeneous or heterogeneous database. The streams are used to perform different functions like replication, message queuing, loading data into warehouse, event notification and data protection. You need to gain huge data management skills to get placed in the job of oracle streams. Oracle stream interview questions and answers at wisdomjobs.com portal gives you a detailed list of job interview questions and answers for you to go through. These questions listed at the portal will help you stand out of the competition and win the game. Referring Oracle streams interview questions and answers before interview will help to brush your knowledge.
Streams pool is a part of System Global Area (SGA) from which memory for Streams is allocated if it is configured. It can be configured by specifying initialization parameter, STREAMS_POOL_SIZE.
If the size of the Streams pool is greater than zero, then any SGA memory used by Stream is allocate from the Streams pool.
If the size of the Stream pool is equal to zero, then the memory used by Streams is allocated from the shared pool that may use up to 10% of the shared pool.
Database Change Notification is a service that is used to notify the registered clients whenever a change is committed.
Following are some important Streams views:
Generally, capture process functions at source database.
However, if you want to save resources at the source database, you can set up another database for the capture process only.
The feature which allows you to move capture process to another database is called downstream capture.
LCR contains database changes, streams require the changes to be captured in specific format. LCR keeps the changes in that format.
DML handler can be set by using the following statement:
Dbms_apply_adm.set_dml_handler (object_name, object_type, operation_name, error_handler, user_procedure, apply_db_link)
Default logging process records the information about DML operations.
Supplemental logging is required to identify the rows to be updated on each destination.
The oracle streams product from Oracle Corporation encourages users of Oracle databases to propagate information within and between databases.
It provides tools to capture, process (stage), and manage database events through Advanced Queuing Queues.
You can find the setup of lob_assembly by using the DBA_APPLY_DML_HANDLER view.
Capture process extracts database changes from redo log files at source. It is a background process.
When the apply process applies the LCR directly at the target, it is called direct apply.
The apply process is a background process that runs on target database.
It dequeues messages (LCR) and applies those to the target database either directly or through handler.
SYS.AnyData is a queue that can capture messages of type AnyData.
This is a standard used in the Streams replication for storing LCRs.
The reason for using this queue is that messages are wrapped into type AnyData before queuing.
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.
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.
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.
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.
You could use Logminer or Streams
Naming of the NIC device driver has the following constraints:
The name can contain alphanumeric and underscore (_) characters only
The first and last characters of the name cannot be a number
The name length cannot exceed 16 characters. The recommended length is 3–8 characters
IP is a STREAMS module in the Oracle Solaris operating environment. Any module or driver interface with IP should follow the STREAMS mechanism. There are no specific requirements for the interface between IP and network drivers.
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