R

radar chart

SEE chart, radar.

Radio Frequency IDentification (RFID)

Technology for tracking the location of goods. RFID tags are transponders, devices that upon receiving a radio signal transmit one of their own. Transponders were first used during World War II as a means of identifying friendly aircraft, but now RFID technology is becoming economical for widespread use. While their main function remains identification, they can also be used for detecting and locating objects as well as monitoring an object’s condition and environment.

RAID 0

Block striping without parity or mirroring. A method of data storage configuration consisting of writing blocks of data across different data storage devices with no redundancy so that no two contiguous blocks of data are written to the same storage device. This method allows contiguous blocks to be accessed simultaneously, improving I/O performance. If one device fails, the data is lost. This method is best suited for volatile storage where speed is more important than failure prevention. SEE ALSO Redundant Array of Independent Disks.

RAID 0+1

Striped sets in a mirrored set. A second striped set is created to mirror the original striped set. If devices fail within one mirrored set, data can be recovered from the other mirror, but if devices fail within both mirrored sets, the data may be lost. SEE ALSO Redundant Array of Independent Disks.

RAID 1

Mirroring without parity or striping. A method of data storage configuration consisting of simultaneous writes over mirrored data storage devices. If one device fails, all data can be recovered from the other. SEE ALSO Redundant Array of Independent Disks.

RAID 10

Alternate form: RAID 1+0

Mirrored sets in a striped set. A method of data storage configuration consisting of stripes of blocks across a number of mirrored drives, combining RAID 0 and RAID 1 techniques. If any device fails, the data can be recovered from blocks on other drives as long as no mirror loses all disks. SEE ALSO Redundant Array of Independent Disks.

RAID 2

Bit-level striping with Hamming code parity disks. A method of data storage configuration where the disk rotation is synchronized and the bits and calculated parity are distributed across the disks such that all bits in a byte can be read at once with multiple spindles, resulting in very fast reads. If one device fails, it may be possible to reconstruct the data from the parity data written to other disks. SEE ALSO Redundant Array of Independent Disks.

RAID 3

Byte-level striping with parity disks. A method of data storage configuration where the disk rotation is synchronized and the bytes and parity are distributed across the disks such that sequential bytes can be read at once with multiple spindles, resulting in fast reads. If one device fails, it is possible to reconstruct the data from the parity data written to other disks. SEE ALSO Redundant Array of Independent Disks.

RAID 4

Block striping with a parity disk. A method of data storage configuration where sequential blocks are stored on different disks, and parity is calculated and stored on another disk. May have performance bottlenecks due to the parity being limited to one disk. If one device fails, it is possible to reconstruct the data from the parity data written to other disks. SEE ALSO Redundant Array of Independent Disks.

RAID 5

Block striping with striped parity. A method of data storage configuration where sequential blocks are stored on different disks, and parity values for those blocks are striped along with the data. If one device fails, the data can be reconstructed from the parity data written to other storage devices. SEE ALSO Redundant Array of Independent Disks.

RAID 6

Block striping with double distributed parity. A method of data storage configuration where sequential blocks are stored on different disks, and parity is calculated and stored twice on different disks. If up to two devices fail, the data can be reconstructed from the parity data written to other storage devices. SEE ALSO Redundant Array of Independent Disks.

Random Access Memory (RAM)

1. A form of data storage that uses integrated circuits that allow changes in the data contents. Originally called Read Alterable Memory, to distinguish from Read Only Memory (ROM), which is still used.
2. Memory in which the time to access any unit of information, is the same as the time to access any other unit of information. Also called uniform access memory.

range

A restricted set of attribute values, defined by a pair of minimum and maximum, or start and end, values.

range partitioning

SEE partitioning, range.

Rapid Application Development (RAD)

Methods, tools and techniques that dramatically accelerate application development time.

rate

A class word, abbreviated usually to rt.

readiness assessment

A process of reviewing environmental, resource and work effort measurements in order to predict success of an implementation.

Read-Only Memory (ROM)

A form of data storage that uses integrated circuits that is written to once, and then static afterwards. Usually mass-produced in a factory as a secure distribution method for code and/or data.

real number

A number that contains no imaginary components, of unspecified precision. Almost always displayed with decimal points. Contrast with integer.

real time

Alternate form: real-time

1. Adjective. Refers to the utmost level of timeliness regarding the use of information. Commonly defined as instantly or instantaneous, although not strictly the same.
2. The condition in which the time to process and respond to a request for information (processing) is less than the time in which it is needed in the environment (the source of the request) to make a difference.

real time data

Alternate form: real-time data

Up-to-the-second, detailed data used to run the business and accessed in read/write mode, usually through predefined transactions.

real time data warehousing

Alternate form: real-time data warehousing

SEE Data Warehouse, active.

Real Time OLAP (RTOLAP)

Alternate form: Real-Time OLAP

SEE OnLine Analytical Processing, Real Time.

reasonableness

Expectations within specific operational contexts. (DAMA-DMBOK Guide, 1st edition, pg. 297.)

record

1. Generally, evidence of an organization's activities. These activities can be events, transactions, contracts, correspondence, policies, decisions, procedures, operations, personnel files, and financial statements. Records can be physical documents, electronic files and messages, or database contents.
2. In data management, the physical representation of data about an instance. A collection of fields about an instance generally representing the information pertaining to an instance of a member of the type population.

record-based data modeling scheme

SEE data modeling scheme, record-based.

Records Management (RM)

The management of evidence of an organization's activities. SEE ALSO record, def 1.

recoverability

The ability to reestablish service after interruption, and correct errors caused by unforeseen events or component failures. (DAMA-DMBOK Guide, 1st edition, pg. 134.)

recovery

1. Generally, the restoration of something to its status before an event or at a point in time.
2. In data management, the restoration of a database to its state as of a different point in time, typically in the wake of a hardware or software failure.

Recovery Point Objective (RPO)

The intent to recover data up to a specific point in a transaction stream following a down-time event. Expresses the amount of data an organization may tolerate to lose.

Recovery Time Objective (RTO)

The intent to recover lost applications, within specific time limitations, to assure a certain level of operational continuity. Expresses the amount of time a business will tolerate the computing system (hardware, software, services) to be offline.

recovery, backward

Consists of restoring a snapshot backup copy of the database (a valid snapshot copy of the data as of a point in time), followed by the re-execution of logged change activity since the backup copy was made. This method essentially reverses (rolls back) all changes after the snapshot was taken, and re-executes from that point forward.

recovery, roll-forward

Consists of restoring a full backup copy of the database, followed by re-execution of logged change activity since the backup copy was made. This method essentially starts over from a full copy of the database, and re-executes from that point forward.

recursive

1. Adjective. A process that can be infinitely repeated using one instance of the execution of the process as the input of the next instance of execution. A process calling itself.
2. Sometimes used to refer to a relationship in a data structure. SEE ALSO relationship, reflexive.

recursive relationship

SEE relationship, recursive.

redundancy

The storage of multiple copies of logically identical data. Physically, the data may or may not be identical across systems, and it is not known which is most current or accurate.

redundancy control

Management of a distributed data environment to limit excessive copying, update, and transmission costs associated with multiple copies of the same data. Data replication is a strategy for redundancy control with the intention to improve performance. SEE ALSO managed replication.

Redundant Array of Independent Disks (RAID)

A technology for configuring a logical data storage device across multiple physical devices to improve performance, availability or both. The primary goal is fault tolerance as in most configurations data can be recovered after a device failure and in some cases, without interruption. SEE ALSO RAID 0; RAID 1; RAID 10; RAID 0+1; RAID 2; RAID 3; RAID 4; RAID 5; RAID 6.

reference & master data management

Ensuring consistency with a “golden version” of data values. Managing golden versions and replicas. One of ten data management functions identified in the DAMA-DMBOK Functional Framework. (DAMA-DMBOK Guide, 1st edition, pg. 6.)

reference data

1. Generally, any data used to organize or categorize other data, or for relating data to information both within and beyond the boundaries of the enterprise. Usually consists of codes and descriptions or definitions.
2. In financial services, refers to both reference and master data together.

Reference Data Management (RDM)

Processes that control vocabularies (defined domain values), including control over standardized terms, code values and other unique identifiers, business definitions for each value, business relationships within and across domain value lists, and the consistent, shared use of accurate, timely, and relevant reference data values to classify and categorize data. (DAMA-DMBOK Guide, 1st edition, pg. 171.)

reference data, location

Reference data that includes geopolitical data such as countries, states or provinces, counties, postal codes, sales territories, etc. (DAMA-DMBOK Guide, 1st edition, pg. 180.)

reference entity

SEE entity, reference.

referential integrity

1. In data management, constraints that govern the relationship of an occurrence of one entity to one or more occurrences of another entity. These constraints may be automatically enforced by the DBMS. For instance, every purchase order must have one and only one customer. If the relationship is represented using a foreign key, then the foreign key is said to reference a file or entity table where the identifier is from the same domain. Having referential integrity means that IF a value exists in the foreign key of the referencing file, then it must exist as a valid identifier in the referenced file or table.
2. The condition that exists when all intended references from data in one column of a table to data in another column in the same or a different table are valid. (DAMA-DMBOK 1st edition, pg. 297.)

reflexive relationship

SEE relationship, reflexive.

refresh

A process of taking a snapshot of data from one environment and moving it to another environment, overlaying old data with the new data each time.

registry

1. Generally, a permanent collection of data related to some topic or collected through some process.
2. In Meta-data Management, an application which stores meta-data for querying, and which can be used by any other application in the network with sufficient access privileges.

regression

Using one data set to predict the results of a second.

regression analysis

A statistical technique which seeks to find a line which best fits through a set of data as plotted on a graph, seeking to find the cleanest path which deviates the least from any instance within the set.

regulatory compliance

The act of meeting the requirements of government legislation or self-regulating industry organizational mandates. For instance, public companies are required to provide specific financial reporting and disclosure. Regulators in the U.S. include the securities authorities (the SEC), tax authorities (the IRS) and banking authorities (the FDIC).

relation

1. Generally, the manner in which two objects may be associated, ordered, connected, or otherwise grouped, using inherent attributes.
2. In data management, a physical structure (a flat file, inverted list, linked list, bitmap, hash table, b-tree, etc.) consisting of a set of one or more columns and zero or more rows. The relation is between the row category and column category.
3. DCMI element in element set Content: a relationship between any two resources or a resource and another instance of that same resource. SEE ALSO Dublin Core Metadata Initiative.

relational data modeling scheme

SEE data modeling scheme, relational.

relational database

SEE database, relational.

Relational DataBase Management System

SEE DataBase Management System, Relational.

Relational Definition Framework (RDF)

SEE Resource Description Framework.

Relational OLAP (ROLAP)

SEE OnLine Analytical Processing, Relational.

relationship

1. Generally, an instance of a connection between two or more things.
2. In data management, a link between two entities describing the business rules governing how the two entities interact in the real world, including their cardinality and dependency. Typically described using Verb parts of speech.

relationship cardinality

SEE cardinality.

relationship generalization

SEE generalization, relationship.

relationship notation

In data modeling, the particular graphical representation of a relationship and its characteristics. Most frequently, a relationship is represented by an arc drawn between two related things, with additional notations to reflect its characteristics. For example, the multiplicity characteristic of many (more than one) could be represented by a fork, an arrow, a double headed arrow, an asterisk, or the letter M.

relationship rule analysis                              association rule analysis

In data analysis, a method for finding relationships between variables that exceed a rate of frequency or some other measure to determine a minimum significance.

relationship, attributed

In data modeling, a relationship between two entity types which itself has attributes. If the relationship is M:M, then the attributes on the relationship cannot logically be stored in either of the related entities.

relationship, binary

In data modeling, a relationship that involves two entity types or object types. The relationship could be defined on a single entity type, in which case it is called a reflexive relationship. In such a relationship, the members play different roles in the relationship, for example, a boss-employee relationship where all bosses are employees. Some have called a reflexive relationship unary because it involves a single population, but that is incorrect. It is still binary, with the members playing two different roles in the relationship.

relationship, contingent

In data modeling, a relationship where an instance of one entity is required, but an instance of the other entity is not required. Example: A product may not have any orders, but each order must have at least one product.

relationship, hierarchical

In data modeling, a one-to-many relationship between two entity types (which could be the same entity type, SEE relationship, reflexive), in which the entity type on the many side of the relationship is dependent upon the entity type on the one side; sometimes called a parent-child relationship. An instance of the child must relate to one and only one instance of the parent entity type.

relationship, identifying

In data modeling, a relationship where the child instance cannot be uniquely identified without knowing the parent instance or the identifier (key) of the parent instance in

that relationship.

relationship, mandatory

In data modeling, a relationship where the both instances are required to be present. Example: An account must have an account holder. Each account holder must have at least one account.

relationship, non-identifying

In data modeling, a relationship where the child instance can be uniquely identified without knowing the parent instance or the identifier (key) of the parent instance in that relationship.

relationship, optional

In data modeling, a relation instance where not all instances of either entity participate in the relationship. Example: A company location may not have assigned orders (a data center), and orders may not have assigned company locations (for a service done over the phone).

relationship, recursive

1. In data modeling, a relationship within processes in which a process calls itself during execution. Sometimes used to refer to a reflexive relationship in a data structure.
2. SEE relationship, recursive.

relationship, reflexive

In data modeling, a relationship in a data structure in which individual instances are related to other instances of the same type, i.e., in the same file or table. For example, in an employee table, an employee could be related to some other employee who is their boss. Sometimes (erroneously) called a recursive relationship, which instead applies to a process calling itself.

relationship, ternary

In data modeling, a relationship that involves three entity types or object types. If only two of the participating entity types are required to uniquely identify instances of the relationship, then it would also be an attributed, binary, many-to-many relationship. For example, Employee, Skill, and Proficiency Level. For each Employee-Skill combination (a M:N relationship), if there can only be at most one Proficiency Level, then it can be viewed as a binary relationship between Employee and Skill, and Proficiency Level would be an attribute of the binary relationship.

relative address pointer

A method of assigning pointer values based on a start point other than the root of the structure.

release management

The process responsible for planning, scheduling and controlling the movement of Releases to test and live environments. The primary objective of Release Management is to ensure that the integrity of the live environment is protected and that the correct components are released. SEE ALSO ITIL.

reliability

1. Generally, closeness of the initial estimated value to the subsequent estimated value.
2. In data management, the ability for a technology component (server, application, database, etc.) or group of components to consistently perform its functions within stated timeframes.

Remote Method Invocation (RMI)

A technique used to create, distribute and use Java objects.

Remote Procedure Call (RPC)

A mechanism for invoking a service on another platform, or the communication using that mechanism that invokes execution of a subroutine or process on a different system.

repeating group

A group of data items that together describe something; an attribute with multiple values within an instance of its parent entity. When related to some other entity in a “something-to-many” relationship, and stored in the related entity type, it becomes a “sub-entity” within that “parent” entity. (Everest 2010) Also called a nested relation.

replication

1. Generally, the process of making copies of something.
2. In data management, the copying of data from a data source to one or more target environments based on rules.

replication transparency

In data management, the state when data is replicated but users cannot see which one of the duplicated systems is fulfilling the data request.

reporting

An automated business process or related functionality that provides a detailed, formal account of relevant or requested information.

repository

1. SEE meta-data repository.
2. Loosely used, any database or file (not recommended for use).

repository environment

SEE meta-data repository; managed meta-data environment.

requirement

1. A customer expectation of a product or service. May be formal or informal, stated or unstated, needed or desired.
2. A formal statement of need for data, functionality or other characteristic.

requirement specification

The formal documentation of requirements, typically using standardized formats and templates, often stored in a requirements database for further analysis and validation/testing/verification.

requirement, business

Requirements stated in business terms or ordinary language what must be delivered or accomplished in order to return value.

requirement, functional

A description of expected behavior of a system given a defined set of inputs or events.

requirement, non-functional

A description of expected operation of a system separate independent of any specific tasks or functions, and may not be measureable in the same terms as other requirements. Includes reliability, efficiency, portability, etc.

requirements analysis

The elicitation, specification and modeling of requirements.

reserved word

A term that has meaning outside of a computer language, and therefore may not be used for other than its defined purpose.

Resource Description Framework (RDF)

Alternate form: Resource Description Format

The basic technique for expressing knowledge on The Semantic Web.

responsibility

1. Accountability for performance of a function, activity or task by a role.
2. In object-oriented design, synonymous with a method.

Responsible Accountable Consulted Informed matrix (RACI matrix)

A matrix used to describe classes of involved parties and their impact on a situation by role.

retention

1. Generally, the process of keeping something in place.
2. In data management, the length of time that data is stored or archived before purging.

Return On Investment (ROI)

The calculated financial return on a business initiative, comparing costs and benefits for a period of time.

reverse engineering

The process of deriving a draft physical model representing an implemented system (application and/or database) from automated scanning of the implemented application and database objects, as a first step towards redesign.

reverse index

SEE index, reverse.

rich picture

SEE chart, rich picture.

right join

SEE join, right.

rights

1. Generally, the entitlements or freedoms that may or may not be acted upon by an entity.
2. In database management, the permissions to perform CRUD activities assigned to a user or role.
3. DCMI element in element set Intellectual Property: rules regarding access to and through a resource. SEE ALSO Dublin Core Metadata Initiative.

rights management meta-data

SEE meta-data, rights management.

risk assessment

A process to identify potential situations that could cause change to an effort from both internal and external forces, assign severity and priority ranks in order to determine overall risk, managing a situation or project to mitigate or minimize the occurrence of risk, and if the risk materializes, to minimize loss or damage.

risk management

Managing a situation or project so that minimum loss or damage will result if a risk identified by a risk assessment materializes.

roadmap

Defines the actions required to move from current to future (target) state. Similar to a high-level project plan.

role

1. Generally, a label assigned to a set of connected behaviors, rights and obligations.
2. In data modeling, the way in which entities of one type relate to entities of another type in a relationship. SEE ALSO Object Role Model.
3. In data security, a name used to refer to the logical set of related responsibilities assignable to a person or organization, and to parties with these assigned responsibilities.

role class

SEE class, role.

roles and responsibilities

One of the DAMA Functional Framework Environmental Elements. The business and IT roles involved in performing and supervising the function, and the specific responsibilities of each role in that function. Many roles will participate in multiple functions. (DAMA-DMBOK Guide, 1st edition, pg. 13.)

roll down

Alternate form: roll-down

SEE Drill Down.

roll up

Alternate form: roll-up

SEE Drill Up.

roll up query

Queries that summarize data at a level higher than the previous level of detail.

rollback

To undo the database statements performed prior to a commit of the transaction.

roll-forward recovery

SEE recovery, roll-forward.

rolling forecast

A forecasting method that shifts planning away from historic budgeting and forecasting and moves it toward a continuous predictive modeling method. It requires access to relevant information from multiple data sources as well as business processes throughout the enterprise. Rolling forecasts can be updated continuously throughout the year to improve accountability.

root cause

The underlying fundamental cause of a problem. Also known as the basic problem, as opposed to a symptom.

rooted

A graph in which one node is designated as the root node (starting point) for a search.

rose diagram

SEE chart, polar area.

row

A set of column values describing one logical instance in a relational database table. Technically called a tuple in relational calculus. Equivalent to a record in a flat file.

RSA encryption (RSA)

A public key encryption program, named for the authors (Rivest, Shamir, Adleman). SEE ALSO encryption.

rubber-banding

The movement of a line or object with one point held fixed and the rest of the object stretches or compresses around that point as other points are moved.

rule

A statement that applies logic or an algorithm to information values to determine a resulting output or action, or to constrain the data relation or its valid values.

rule, authorization

Criteria used to determine whether or not a person or software agent has permission to access data or perform a process.

rule, business

1. Generally, a formally stated constraint governing the characteristics or behavior of an object or entity, or the relationship between objects or entities, used to control the complexity of the activities of an enterprise.
2. In data quality, constraints that can be used to validate the contents of a database. The defined characteristics of a database actually constitute business rules, such characteristics as dependency/optionality, multiplicity/exclusivity, and value set constraints.

rule, duplicate identification match

In data analysis, a rule that focuses on a specific set of attributes that uniquely identify an entity and identify merge opportunities without taking automatic action. (DAMA-DMBOK Guide, 1st edition, pg. 186.)

rule, match-link

In data analysis, a rule that identifies and cross-references records that appear to relate to a master record, without updating the content of the cross-referenced record. (DAMA-DMBOK Guide, 1st edition, pg. 186.)

rule, match-merge

In data analysis, a rule that matches records and merges the data from these records into a single, unified, reconciled, and comprehensive record. (DAMA-DMBOK Guide, 1st edition, pg. 186.