Oracle Developer

A database link is a named object that describes a path from one database to another.

Hash clusters are better choice when a table is often queried with equality queries. For such queries the specified cluster key value is hashed. The resulting hash key value points directly to the area on disk that stores the specified rows.

Private Database Link, Public Database Link & Network Database Link.

Private database link is created on behalf of a specific user. A private database link can be used only when the owner of the link specifies a global object name in a SQL statement or in the definition of the owner's views or procedures.

Public database link is created for the special user group PUBLIC. A public database link can be used when any user in the associated database specifies a global object name in a SQL statement or object definition.

Network database link is created and managed by a network domain service. A

network database link can be used when any user of any database in the network specifies a global object name in a SQL statement or object definition.

ORACLE databases data is stored in data blocks. One data block corresponds to a specific number of bytes of physical database space on disk.

A data block size is specified for each ORACLE database when the database is

created. A database users and allocated free database space in ORACLE datablocks. Block size is specified in INIT.ORA file and cannt be changed latter.

ORACLE database is comprised of three types of files. One or more Data files, two are more Redo Log files, and one or more Control files.

Tablespaces and the Databases Schema Objects.

A database is divided into Logical Storage Unit called tablespaces. A tablespace is used to grouped related logical structures together.

Every ORACLE database contains a tablespace named SYSTEM, which is automatically created when the database is created. The SYSTEM tablespace always contains the data dictionary tables for the entire database.

Each databases logically divided into one or more tablespaces One or more data files are explicitly created for each tablespace.

A schema is collection of database objects of a User.

Schema objects are the logical structures that directly refer to the database's data.

Schema objects include tables, views, sequences, synonyms, indexes, clusters, database triggers, procedures, functions packages and database links.

Yes.

A table is the basic unit of data storage in an ORACLE database. The tables of a database hold all of the user accessible data. Table data is stored in rows and columns.

A view is a virtual table. Every view has a Query attached to it. (The Query is a SELECT statement that identifies the columns and rows of the table(s) the view uses.)

Yes.

Views do not contain or store data.