H

half duplex

Adjective. Describes a system that allows communication between two endpoints where only one may transmit at a time. SEE ALSO simplex; full duplex.

Hamming code

A class of binary linear codes used for parity calculation that can detect up to two simultaneous bit errors, rather than just odd numbers of errors. Named for Richard Hamming. Used in computer memory (RAM) and telecommunications for validating data transmission.

hash

Alternate form: hashing

1. Data allocated in an algorithmically randomized fashion in an attempt to evenly distribute data and smooth access patterns.
2. Verb. To calculate a hash key for data.

hash key

Alternate form: hashed key

SEE key, hash.

hash partitioning

SEE partitioning, hash.

Health Insurance Portability and Accountability Act, The (HIPAA)

A law enacted by the U.S. Congress in 1996. Title I of HIPAA protects health insurance coverage for workers and their families when they change or lose their jobs. Title II requires the establishment of national standards for electronic health care transactions and national identifiers for providers, health insurance plans, and employers. Title II also addresses the security and privacy of health data. The standards are meant to encourage use of electronic data interchange in US healthcare.

heat map

SEE chart, heat map.

heaven and hell chart

SEE chart, heaven and hell.

help desk

SEE call center.

heterogeneous

Adjective. Describes multiple members in a set that have differences in nature or structure. Opposite of homogeneous.

heuristics

“Rules of thumb” and approximation methods for obtaining a goal, a high quality solution, or improved performance. It sacrifices completeness to increase efficiency, as some potential solutions would not be practicable or acceptable due to their 'rareness' or 'complexity'. This method may not always find the best solution, but it will find an acceptable solution within a reasonable timeframe for problems that will require almost infinite or longer than acceptable times to compute.

hexadecimal

A numbering system using a base of 16, using letters A through F to represent 10 through 15 decimal. A byte is generally 8 binary digits, so that 1 hexadecimal representation represents 4 binary digits. Core dumps are expressed in hexadecimal for example.

hierarchical data model

SEE data model, hierarchical.

hierarchical database

SEE database, hierarchical.

Hierarchical Query Language (HQL)

A high-level language on a hierarchical data structure, similar to SQL on a multi-file data structure.

hierarchical relationship

SEE relationship, hierarchical.

hierarchical structure

SEE structure, hierarchical

hierarchical taxonomy

SEE taxonomy, hierarchical.

hierarchy

1. Generally, a classification structure arranged in levels of detail from the broadest to the most detailed level. Each level of the classification is defined in terms of the categories at the next lower level of the classification.
2. In dimensional modeling and dimensional databases, the organization of a dimension’s members based on parent-child relationships, typically where a parent member represents the consolidation of child members.

high availability

A protocol and associated execution that ensures a certain relative degree of computing-system operational continuity in any down-time event.

histogram

A chart that shows quantities of data points that occur within various numeric ranges.

historical database

SEE database, historical.

historical revisionism

The reinterpretation of historical data based on new data, validated or invalidated assumptions about the data, or different perspectives on the environment that generated the data.

homogeneous

Adjective. Describes multiple members in a set that have no differences in nature or structure. Opposite of heterogeneous.

homogeneous nodes

A set of nodes conforming to the same definition (or of the same type).

homonym

A term that has the same or nearly same spelling or sound as another term, but has a different meaning. Contrast with synonym.

horizontal abstraction

SEE abstraction, horizontal.

horizontal partitioning

SEE partitioning, horizontal.

host-driven

Adjective. Describes a processing method in which the host computer controls the session. A host-driven session typically includes terminal emulation, front ending, or client/server types of connections. The host determines what is displayed on the desktop, receives user input from the desktop, and determines how the application responds to the input.

hot backup

SEE backup, hot.

house of quality chart

SEE chart, house of quality.

householding

Consolidating related names and addresses into groups.

How

Zachman Framework column name, matches Process Transformations.

human interface

An interface from a system to a human that enables the human to interact with and receive information from that system. SEE ALSO interface.

Hybrid OLAP (HOLAP)

SEE OnLine Analytical Processing, Hybrid.

hype-cycle chart

SEE chart, hype-cycle.

hyperbolic tree

SEE chart, hyperbolic tree.

hypercube

An OLAP product that stores all data in a single data cube which has all the application dimensions applied to it.

hyperlink

A one-way reference from one electronic document to another. Most frequently implemented as navigational links from one web page to another.

hypertext

Electronically stored text data organized into documents and logical sections that can be accessed randomly via hyperlinks as well as sequentially.

Hypertext Markup Language (HTML)

A tag set used to create a web page document; a subset of SGML (standard generalized markup language). The tags or elements tell the browser how to display the information. The tags are used to “mark,” in a hierarchical format, the different components of the document.

HyperText Transfer Protocol (HTTP)

A system of communicating between a web browser application and a document stored on a web server.