- Industry: Consulting
- Number of terms: 1807
- Number of blossaries: 2
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Gartner delivers technology research to global technology business leaders to make informed decisions on key initiatives.
The RDBMS architecture is based on a formal method of constructing a database in rows and columns using rules that have formal mathematical proofs. RDBMSs originated in the work of E.F. Codd. In an RDBMS, relationships among tables are created by comparing data, such as account numbers and names. In addition, an RDBMS has the flexibility to take any two or more tables and generate a new table from the rows that meet the matching criteria.
RDBMSs are implemented in many different ways. For example, they can be implemented on disk storage using relational or row storage techniques, stored as columns or indexes as in column-based storage, implemented in memory as the in-memory storage model, and even implemented in flash memory. In addition, RDBMS engines are available with different footprints that can be used as embedded DBMS engines in edge devices, as well as in portable or mobile devices. We also do not distinguish data types any longer because most RDBMSs available today allow multiple data types, including objects, user-defined data types, BLOBs and native XML structures.
Industry:Technology
A database management system (DBMS) that incorporates the relational-data model, normally including a Structured Query Language (SQL) application programming interface. It is a DBMS in which the database is organized and accessed according to the relationships between data items. In a relational database, relationships between data items are expressed by means of tables. Interdependencies among these tables are expressed by data values rather than by pointers. This allows a high degree of data independence.
Industry:Technology
Regulatory compliance is concerned with laws that a business must obey, or risk legal sanctions, up to and including prison for its officers.
Industry:Technology
A method of mirroring or striping data on clusters of low-end disk drives; data is copied onto multiple drives for faster throughput, error correction, fault tolerance and improved mean time between failures.
With the exception of RAID 0, all RAID levels provide automated recovery of data in the event of a disk failure. The RAID levels and their key features are:
• RAID-0 — provides disk striping without parity information; data is written by segment across multiple disks sequentially until the end of the array is reached, and then writing starts at the beginning again. Provides greater logical disk capacity with faster access time on reads (multiple segments read simultaneously). However, RAID-0 provides no data redundancy — if one drive fails, the entire disk array subsystem is unavailable.
• RAID-1 — provides fault tolerance by using disk mirroring (also called shadowing). Each byte of data on a disk is duplicated on another physical drive, providing 100% data redundancy. RAID-1 provides immediate access to data when either the primary or secondary drive fails, but it has the highest cost of all RAID types, since duplicate hardware is required.
• RAID-2 — eliminates the 100% redundancy overhead of RAID-1 by using a powerful error detection and correction code (Hamming), with bits of the data pattern written across multiple disks.
• RAID-3 — similar to RAID-2, but uses a single check disk per group that contains the bit parity of the data disks; data is interleaved across all disks. Because disk reads are performed across the entire array and all data is transferred to the controller in parallel, RAID-3 is well suited for applications that require high data read/write transfer rates for large sequential files.
• RAID-4 — instead of interleaving blocks of data across all drives, writes the first block on drive 1, the second block on drive 2, and so on. This technique dramatically improves read time, since many reads are single block (single drive), freeing other drives for additional read requests.
• RAID-5 — eliminates the dedicated parity drive by writing parity with the data across all drives in the array. Consequently, the single-write restriction and some performance degradation of RAID-1 through RAID-4 are eliminated. If a drive fails, the controller can rebuild the data from the parity and data on the remaining drives.
• RAID-6 — provides two-disk parity and one spare, so that two simultaneous disk failures per array of disks can be tolerated. With the occurrence of a failure, a spare is brought online and transparent reconstruction begins automatically in the background with negligible impact on performance.
• RAID-10 — a combination of RAID-0 and RAID-1 that provides the benefits of striping and fault tolerance (disk mirroring).
Industry:Technology
1. Portion of the total information contained in a message that can be eliminated without loss of essential information.
2. Provision of duplicate, backup equipment or links that immediately take over the function of equipment or transmission lines that fail.
Industry:Technology
A processor architecture that shifts the analytical process of a computational task from the execution or runtime to the preparation or compile time. By using less hardware or logic, the system can operate at higher speeds. RISC cuts down on the number and complexity of instructions, on the theory that each one can be accessed and executed faster, and that less semiconductor real estate is required to process them. The result is that for any given semiconductor technology, a more powerful microprocessor can be produced with RISC than with complex instruction set computer (CISC) architectures.
This simplification of computer instruction sets gains processing efficiencies. That theme works because all computers and programs execute mostly simple instructions. RISC has five design principles:
• Single-cycle execution — In most traditional central processing unit (CPU) designs, the peak possible execution rate is one instruction per basic machine cycle, and for a given technology, the cycle time has some fixed lower limit. Even on complex CPUs, most compiler-generated instructions are simple. RISC designs emphasize single-cycle execution, even at the expense of synthesizing multi-instruction sequences for some less-frequent operations.
• Hard-wired control, little or no microcode — Microcode adds a layer of interpretive overhead, raising the number of cycles per instruction, so even the simplest instructions can require several cycles.
• Simple instructions, few addressing modes — Complex instructions and addressing modes, which entail microcode or multicycle instructions, are avoided.
• Load and store, register-register design — Only loads and stores access memory; all others perform register-register operations. This tends to follow from the previous three principles.
• Efficient, deep pipelining — To make convenient use of hardware parallelism without the complexities of horizontal microcode, fast CPUs use pipelining. An n-stage pipeline keeps up to “n” instructions active at once, ideally finishing one (and starting another) every cycle. The instruction set must be carefully tuned to support pipelining.
Industry:Technology
Redaction tools are software that is used to edit content and, thereby, selectively and reliably remove information from documents or websites before sharing the remaining content with someone who is not authorized to see the entire original document. The process of “redacting” documents has been used in the legal profession for decades to black out confidential or privileged information during the exchange of documents during litigation. The process has also been used by government agencies to censor sensitive material when responding to Freedom of Information Act (FoIA) requests. In the manual process, someone takes a paper copy of the document and uses a heavy black marker to cross out the information to be excluded. Redaction tools have been included as part of document imaging products since their introduction. In electronic documents, redaction refers to the permanent removal of information, not the masking or obfuscating of data.
Industry:Technology
The process of “redacting” documents has been used in the legal profession for decades to black out confidential or privileged information during the exchange of documents during litigation. In electronic documents, redaction refers to the permanent removal of information, not the masking or obfuscating of data.
Industry:Technology
Records management (RM) technologies enable organizations to enforce policies and rules for the retention and disposition of content required for documenting business transactions, in addition to automating the management of their record-retention policies. These technologies, implemented with well-formulated and consistently enforced RM strategies and policies, form an essential part of the organizationwide life cycle management of information. RM principles and technologies apply to both physical and electronic content.
Industry:Technology
Reconfigurable optical add/drop multiplexers (ROADMs) are the wavelength division multiplexing (WDM) equivalent of the add/drop multiplexing that has been used in the Synchronous Digital Hierarchy (SDH) and Synchronous Optical Network (SONET) markets for more than a decade. ROADMs enable communications service providers (CSPs) to automate the way individual wavelengths of WDM systems are routed through their networks, mainly in ring configurations, with protection switching and easy provisioning being the major benefits.
Industry:Technology
