Método de Sefeñan

A bank that contains data belonging to a program or a UDS common bank.

data access control

An RDMS security mechanism for designating the owner of a table and establishing control over access to data in the table.

Data Definition Facility (DDF)

The UREP component for defining FDTs and RDTs.

data integrity

Data accuracy and consistency.

data item

The intersection of a column and a row in a table. The part of a row that contains one category or entity of data such as a last name, a person’s age, or a social security number. Items that fall into the same category in a table are listed in the same column.

See also data value.

Data Management System (DMS)

The Unisys data management software product that conforms to the CODASYL (network) data model and enables data definition, manipulation, and maintenance in mass storage database files.

data model

A means of organizing and representing information. See also relational data model.

data page

A portion of a table that a contains a number of data records, arranged to facilitate I/O operations to and from the storage area and to serve as the basis for recovery of the storage area. See also page.

data page number

A number assigned by RDMS to each data page it creates in a B-tree to uniquely identify the page.

data storage definition (DSD)

The process that defines data storage areas and associates each storage area with an Exec or TIP file.

data type

A description of the characteristics of the data values allowed such as numeric, date, time, and timestamp.

data value

The specific value of a data item.

database dump

A copy of the database files as they exist at a given point during processing.

deferred update recovery

Synonymfor medium recovery.

definition access control

An RDMS security mechanism for controlling access by users to tables.

definition-level lock

A lock on the FDT or RDT.

degree

The number of columns in a relational table, view, query, or subquery.

DELETE privilege

A privilege that owners of RDMS tables grant to other users to enable them to delete rows. See also data access control.

descriptive text

The text that describes a data file (similar to comment lines in a program).

diacritical mark

A mark such as a circumflex ( ^ ) or tilde ( ~ ) added to a character to indicate a phonetic value different from the base character. Seealso ISO 646:1983.

dieresis

Also spelled diaeresis. Two dots over the second of two adjacent vowels in a word to indicate two separate sounds. In German, the two dots (Umlaut) occur over a single vowel and indicate a change in the vowel sound caused by partial assimilation to a vowel or semivowel in the following syllable. Seealso diacritical mark.

DMS

See Data Management System.

DSD

See data storage definition.

DSR

See dynamic system reconfiguration.

dump

See database dump.

dynamic ESQL

See embedded SQL.

dynamic system reconfiguration (DSR)

The UREP process by which users can dynamically change UDS Control configuration parameters and reconfigure an application group.

E

embedded SQL (ESQL)

SQL statements placed in a UCS COBOL program with the special markers or delimiters, EXEC SQL and END-EXEC. ESQL statements are compiled instead of interpreted and take two forms: static and dynamic. Static ESQL is processed more extensively at compile time than dynamic ESQL and thus executes faster. Dynamic ESQL receives more extensive run-time processing than static ESQL but provides greater flexibility.

encryption

The process of scrambling user-defined data in RDMS database files to protect the information in the files from users who are able but not authorized to access the files or otherwise obtain some form of the data in the files. Contrastwith decryption.

encryption user routine (EUR)

A program written by a system programmer with extensive knowledge of Unisys operating systems to perform the encryption and decryption of RDMS database files.

entity

An object in the repository that defines a piece of information to UREP, such as qualified entity names, entity types, schemas, and tables.

equi-join

A join operation in which the comparison operator is an equal sign.

ESQL

See embedded SQL.

EUR

See encryption user routine.

exclusive lock

A lock that prevents other threads from accessing a file or page until the lock is released.

Exec

See Executive.

Executive

The Unisys core software that controls the system’s operating environment, usually referred to as the “Exec.”

EXISTS function See function.

Extended Processing Complex (XPC)

A systemwide accelerator for data on mass storage device types attached to Unisys operating systems.

Extended Transaction Capacity (XTC)

A group of software components that enables increased processing capacity for TIP database environments as well as for UDS/TIP and UDS/Exec database files running on operating system hardware. The XTC group includes MHTIP and MHFS.

F

FCP

See file control page.

FDT

See file description table.

FETCH privilege

Synonymfor SELECT privilege.

file control page (FCP)

The first page in a relational file that contains general storage information about the file and a list of the root page numbers of the B-trees stored in the file.

file control page B-tree list

A set of two-word entries that contain the internal relation code for each B-tree stored in the file and the page number of the root page for each B-tree stored in the file.

file description table (FDT)

The run-time definition for a storage area that corresponds to the characteristics

described in the repository storage area definition. FDTs reside in the FDT$ file for each application group.

first normal form

A level of normalization in which no repeating groups occur.

flush

To remove a page from memory so that subsequent references to that page must read it from mass storage.

foreign key

A column or columns that establish a relationship between the primary key of one table (parent table) and a column or columns in a second table (child table). One table can be both the parent and child table. Foreign keys limit the acceptable values for a column in one table to the primary key or unique index values in another table.

function

(1) In general terms, a task, operation, special purpose, or action. (2) An operation that optionally uses one or more input parameters but always returns a single output value. RDMS uses two types of built-in functions. An aggregate function retrieves a specific attribute about groups of rows, such as the minimum value of a column. A system function retrieves a dynamic value, such as the current time or user. The Boolean existential function, [NOT] EXISTS, checks for the existence of a row and returns one of the “truth values” (TRUE or FALSE). See also stored function.

H

High-Volume Transaction Processing (HVTIP)

A high-performance transaction processing environment.

hit record

A record that satisfies the condition of the WHERE clause in a query.

HVTIP

See High-Volume Transaction Processing.

hybrid hash join

One of the methods used by RDMS to perform a join operation. RDMS uses the hybrid hash join to equally join the two outermost tables when both tables equally join on nonindexed columns or on nonleading index columns.

I

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