dwh terminology p-t

P
Parallel Data Orgnization an arrangement of data in which the data is spread over independent storage devices and is

managed independently.

Parallel Search Storage a storage device in which one or more parts of all storage locations are queried simultaneously for a

certain condition or under certain parameters.

Parsing the algorithm that translates syntax into meaningful machine instructions. Parsing determines the meaning of

statements issued in the data manipulation language.

Partition a segmentation technique in which data is divided into physically different units. Partioning can be done at

the application or the system level.

Performance the length of time from the moment a request is issued until the first of the results of the request are

received.

Periodic Discrete Data a measurement or description of data taken at a regular time interval.

Prefix Data data in a segment or a record used exclusively for system control, usually unavailable to the user.

Primitive Data data whose existence depends on only a single occurance of a major subject area of the enterprise.

Privilege Descriptor a persistent object used by a DBMS to enformce constraints on operations.

Projection an operation that takes one relation as an operand and returns a second relation that consists of only the

selected attributes or columns, with duplicate rows eliminated.

Proposition a statement about entities that asserts or denies that some condition holds for those entities.


Q
Query Language a language that enables an end user to interact directly with a DBMS to retrieve and possibly modify data

managed under the DBMS.


R
Record an aggregation of values of data organized by their relation to a common key.

Recovery the restoration of the database to an original position or condition, often after major damage to the

physical medium.

Redundancy the practice of storing more than one occurrence of data.

Referential Integrity the facility of a DBMS to ensure the validity of a predefined relationship.

Refresh Refreshing a warehouse consists in propagating updates on source data to correspondingly update the base data and

derived data stored in the warehouse. Two sets of issues to consider; when to refresh and how to refresh. Refresh policy is

set by warehouse administrator, depends on user needs and traffic and may be different for different sources.

Replication The physical copying of data from one database to another.

Reporting The process of translating data to presentation formats via a pre-defined or ad-hoc queries.

ROLAP Relational OLAP. Data warehouses that are implemented on standard or extended relational DBMSs,called Relational

OLAP(ROLAP)servers.These servers assume that data is stored in relational databases.

Roll up to increase or acquire by successive accumulations

Rolling Summary a form of storing archival data where the most recent data has the lowest level of details stored ande the

older datra has higher levels of details stored.


S
Schema The logical organization of data in a database.

Scope of Integration the formal definition of the boundaries of the system being modelled.

Sequential File a file in which records are ordered according to the values of one or more key fields.

Serial File a sequential file in which records are physically adjacent, in sequential order.

Slowly Changing Dimensions The approaches involving maintaining a list or history by adding related rows or new columns,

or simply ignoring the problem by retaining the only the current data.Type I, Type II, Type III

Snowflake Schema A snowflake schema is a set of tables comprised of a single, central fact table surrounded by

normalized dimension hierarchies. Each dimension level is represented in a table. Snowflake schema implement dimensional data

structures with fully normalized dimensions. Star schema are an alternative to snowflake schema.

Star Schema A star schema is a set of tables comprised of a single, central fact table surrounded by de-normalized

dimensions. Each dimension is represented in a single table. Star schema implement dimensional data structures with de-

normalized dimensions. Snowflake schema are an alternative to star schema.

Surrogate Key It has system-generated artificial primary key values, which allows to maintain historical records in the

Data Warehouse more effectively.


T
Table a relation that consists of a set of columns with a heading and a set of rows.

Time Variant Data data whose accuracy is relevant to some one moment in time.

Top down methodology Involves in building a datawarehouse first and then building datamarts..

Transaction Processing the activity of executing many short, fast running programs, providing the end user with consistent
two or three second response time.

Transition Data data possessing both primitive and derived characteristics; usually very sensitive to the running of

the business.