Oracle HTTP Server is managed by OPMN which stands for Oracle Process Manager and Notification Server. With the use of opmnctl utility we can start, stop and restart Oracle HTTP Server. If we don’t use this utility the configuration management infrastructure cannot detect or communicate with the Oracle HTTP Server processes, and problems may occur.

The startproc command for the case of Windows is: ORACLE_HOME\opmn\bin> opmnctl [verbose] startproc ias-component=HTTP_Server.

To stop Oracle HTTP Server, use the stopproc command: Windows: ORACLE_HOME\opmn\bin> opmnctl [verbose] stopproc ias-component=HTTP_Server.

Oracle HTTP Server is the Web server component of Oracle Database. It is based on the Apache HTTP Server. It is robust and reliable server due to following features:

- Provide high availability infrastructure integration with Oracle Process Manager and Notification Server (OPMN), for process management, death detection and failover for Oracle HTTP Server processes.

- Provide Dynamic Monitoring Services (DMS) metrics that give runtime performance statistics for Oracle HTTP Server processes.

- Enable securing of transactions with Secure Sockets Layer (SSL) technology.

- Execute Perl scripts in the same process as the Oracle HTTP Server, or as CGI script.

Basic Replication : Basic replication is implemented using standard CREATE SNAPSHOT or CREATE MATERIALIZED VIEW statements. It can only replicate data and not procedures, indexes replication is always one-way, and snapshot copies are read only.

Advanced Replication : Advanced replication supports various configurations of updatable snapshot, multi-master and update anywhere replication. It is more difficult to configure but allows data and other database objects like indexes and procedures to be replicated.

Differences between Basic and Advanced replications:

- With basic replication, data replicas provide read-only access to the table data whereas advanced replication features extend the capabilities of basic read-only replication by allowing applications to update table replicas throughout a replicated database system.

- With Basic Replication applications can query data from local data replicas. On the other hand with advanced replication, data replicas anywhere in the system can provide both read and update access to a table's data.

The following are the areas of concern for tuning:

- Memory Usage

- Data Storage

- Data Manipulation

- Physical Storage

- Logic Storage

- Network Traffic

Tuning Memory Usage: In Oracle 10g, we can use the Automatic Workload Repository (AWR) toolset to gather and manage statistical data but in case of Oracle 11g, we can use new initialization parameters such as MEMORY_TARGET to further control the overall memory used by Oracle. It helps us to tune the database automatically when we don’t have time to read the AWR report.

Tuning Data Manipulation: There are two ways to tune Data manipulation in Oracle one way is through Conventional Path mode and second is Direct Path mode.

Tuning Physical Storage: We need to tune the physical storage because it limits the disk in database. This can be done by: Distributing I/O, Striping and Mirroring.

We need to first login to the data base as: SQLPLUS followed by user_name/password. Then we need to execute the following query:

CREATE USER user_name IDENTIFIED BY abcd; in this query a user_name suggest the user that is created which has a password abcd which is required for login in database.

An index is a object which is used to improve performance during retrieval of records.

CREATE [UNIQUE] INDEX index_name 

ON employee[emp_id, emp_name,dept_id]

[COMPUTE STATISTICS]

The UNIQUE keyword is used when combined values of the index should be unique.

The COMPUTE STATISTICS during the creation of index optimizes the plan of execution of the SQL statement and improves performance.

The CACHE option means how many sequences will be stored in memory for access by the application objects. The performance is faster. However in case of the database is down the data is memory is lost for the sequence.

The NO CACHE option means values are not stored in memory. So there might be some performance issue. 

A database trigger is procedural code that is automatically executed in response to certain events on a particular table or view in a database. The trigger is mostly used for maintaining the integrity of the information on the database.

Syntax:

CREATE OR REPLACE TRIGGER [Trigger Name] [Before / After / Instead Of]

ON [schema].[table]

<PL/SQL subprogram>

Types of PL/SQL triggers : 

> Row trigger          - The trigger fires for each ROW affected.

> Statement trigger - The trigger is fired once when the condition is matched

> Before and After trigger - The BEFORE trigger run the trigger action before the insert, update or delete statement. The AFTER trigger runs the trigger action after the insert, update or delete statement is executes.