Oracle Questionnaire

What is a Synonym? 

A synonym is an alias for a table, view, sequence or program unit. 

What is a Sequence? 

A sequence generates a serial list of unique numbers for numerical columns of a database's tables. 

What is a Segment? 

A segment is a set of extents allocated for a certain logical structure. 

What is schema? 

A schema is collection of database objects of a User. 

Describe Referential Integrity? 

A rule defined on a column (or set of columns) in one table that allows the insert or update of a row only if the value for the column or set of columns (the dependent value) matches a value in a column of a related table (the referenced value). It also specifies the type of data manipulation allowed on referenced data and the action to be performed on dependent data as a result of any action on referenced data. 

What is Hash Cluster? 

A row is stored in a hash cluster based on the result of applying a hash function to the row's cluster key value. All rows with the same hash key value are stores together on disk. 

What is a Private Synonyms? 

A Private Synonyms can be accessed only by the owner. 

What is Database Link? 

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

What is a Tablespace? 

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

What is Rollback Segment? 

A Database contains one or more Rollback Segments to temporarily store "undo" information. 

What are the Characteristics of Data Files? 

A data file can be associated with only one database. Once created a data file can't change size. One or more data files form a logical unit of database storage called a tablespace. 

How to define Data Block size? 

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 can't be changed latter. 

What does a Control file Contain? 

A Control file records the physical structure of the database. It contains the following information. Database NameNames and locations of a database's files and redolog files.  Time stamp of database creation. 

What is difference between UNIQUE constraint and PRIMARY KEY constraint? 

A column defined as UNIQUE can contain Nulls while a column defined as PRIMARY KEY can't contain Nulls. 

What is Index Cluster? 

A Cluster with an index on the Cluster Key 

When does a Transaction end? 

When it is committed or Rollbacked. 

What is the effect of setting the value "ALL_ROWS" for OPTIMIZER_GOAL parameter of the ALTER SESSION command ? What are the factors that affect OPTIMIZER in choosing an Optimization approach ? 

The OPTIMIZER_MODE initialization parameter Statistics in the Data Dictionary the OPTIMIZER_GOAL parameter of the ALTER SESSION command hints in the statement. 

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