Shared pool in oracle contains cache information that collects, parses, interprets and executes SQL statements that goes against database. This shared pool acts like a buffer for these SQL statements.

Oracle supports 3 transaction isolation levels: 

- Read committed (default)

- Serializable transactions

- Read only

SQL> ALTER USER user_name ACCOUNT LOCK;

SQL> ALTER USER user_name ACCOUNT UNLOCK;

Locking is a mechanism to ensure data integrity while allowing maximum concurrent access to data. It is used to implement concurrency control when multiple users access table to manipulate its data at the same time.

Advantages :

- Avoids deadlock conditions

- Avoids clashes in capturing the resources

A Peoplesoft database is expression which point out a database containing Peoplesoft objects. For Oracle and only for Oracle, Peoplesoft consists in 3 schemas namely:

- PS (PSDBOWNER table owner),

- PEOPLE (for connection checking) and

- SYSADM (by default), the last one contains all the objects/data.

One of the database objects is connected with single Oracle schema, and all processes that connect to the database use the standard PSFT login procedure. PSFT login is used because to refer to the collection of tables in the administrative schema within an Oracle database. Every process that makes a 2-tier connection to the database identifies itself with a PSFT user or operator ID. Hence the interaction goes.

Peoplesoft Database is similar to other database which is used to store data. Peoplesoft database stores data in a table format for system PeopleTools and Application tables. This is independent of the process you use to retrieve that data from PeopleSoft. Inside PeopleSoft database, only three types of tables reside inside the schema: System Catalog tables, PeopleTools tables, and Application data tables. Two of these table types, System Catalog and PeopleTools tables, can be referred to as metadata tables; users make use of Application data tables to store the data they need for their processes.

Oracle Real Application Clusters (RAC) is a software component we can add to a high-availability solution that enables users on multiple machines to access a single database with increased performance. RAC comprises two or more Oracle database instances running on two or more clustered machines and accessing a shared storage device via cluster technology. To support this architecture, the machines that host the database instances are linked by a high-speed interconnect to form the cluster. Oracle RAC offers features in the following areas:

- Scalability

- Availability

- Load balancing

- Failover

Oracle Spatial, often referred to as spatial, provides a SQL schema and functions that facilitate the storage, retrieval, update, and query of collections of spatial features in an Oracle database. Oracle Spatial is designed to make spatial data management easier and more natural to users of location-enabled applications and geographic information system (GIS) applications. Once spatial data is stored in an Oracle database, it can be easily manipulated, retrieved, and related to all other data stored in the database.