openGauss Glossary
Tags: opengauss
Published: 2023-02-22 02:16:54

A – E

ACID

Atomicity, consistency, isolation, and durability (ACID) is a set of properties that guarantee that transactions are processed reliably in a database management system (DBMS).

AZ

Acronym for available zone which usually refers to an equipment room.

bgwriter

A background write thread created when the database starts. The thread is used to flush dirty pages out of the database to a permanent device (such as a disk).

bit

Short for binary digit. The smallest unit of information handled by a computer. One bit expresses a 1 or a 0 in a binary numeral, or a true or false logical condition, and is represented physically by an element such as a high or low voltage at one point in a circuit or a small spot on a disk magnetized one way or the other. A single bit conveys little information a human would consider meaningful. A group of 8 bits, however, makes up a byte, which can be used to represent many types of information, such as a letter of the alphabet, a decimal digit, or other character.

bloom filter

Bloom filter is a space-efficient binary vectorized data structure, conceived by Burton Howard Bloom in 1970, that is used to test whether an element is a member of a set. False positive matches are possible, but false negatives are not. In other words, a query returns either "possibly in set (possible error)" or "definitely not in set". In the cases, Bloom filter sacrificed the accuracy for time and space.

CEK

Acronym for column encryption key.

CIDR

Acronym for classless inter-domain routing. Whereas classical network design for IPv4 sized the network prefix as one or more 8-bit groups, resulting in the blocks of Class A (8-bit), B (16-bit), or C (24-bit) addresses, CIDR allocates address space on any address bit boundary. A CIDR address is in the format of IP address/Number of bits in a network ID. For example, in 192.168.23.35/21, 21 indicates that the first 21 bits are the network prefix and others are the host ID.

CLI

Acronym for command-line interface. A means of communication between a program and its user, based solely on textual input and output. Commands are input with the help of a keyboard or similar device and are interpreted and executed by the program. Results are output as text or graphics to the terminal.

CMK

Acronym for client master key in the full encryption scenario.

CU

Acronym for compression unit. It is the smallest storage unit in a column-store table.

core file

A file that is created for further analysis when memory overwriting, assertion failures, or access to invalid memory occurs in a program, causing a process to fail.

A core file stores memory dump data, and supports binary mode and specified ports. The name of a core file consists of the word "core" and the OS process ID.

The core file is available regardless of the type of platform.

core dump

A core dump, memory dump, or system dump consists of the recorded state of the working memory of a computer program at a specific time, generally when the program stops abnormally. In practice, other key pieces of program state are usually dumped at the same time, including the processor registers, which may include the program counter and stack pointer, memory management information, and other processor and OS flags and information. Core dumps are often used to assist in diagnosing and debugging errors in computer programs.

DBA

Acronym for database administrator who instructs or executes database maintenance operations.

DBLINK

An object of the path from one database to another database. Using DBLINK, you can query a remote database object.

DBMS

Acronym for database management system. It is a piece of system management software that allows users to access information in a database. It is a collection of programs that allows users to access, manage, and query data in a database. A DBMS can be classified as memory DBMS or disk DBMS based on the location of the data.

DCF

Acronym for distributed consensus framework which implements data synchronization based on the Paxos algorithm.

DCL

Acronym for data control language.

DDL

Acronym for data definition language.

DEK

Acronym for data encryption key.

DML

Acronym for data manipulation language.

backup

A backup copy or an act of creating a backup refers to copying and archiving computer data for purposes of recovery in case the original copy of data is lost.

backup and restoration

A collection of concepts, procedures, and strategies to prevent data loss caused by invalid media or misoperations.

standby node

A node in the openGauss primary/standby solution. It functions as a backup of the primary node. If the primary node fails, the standby node is promoted to primary, ensuring uninterrupted data services.

crash

A crash (or system breakdown) is an event that a computer or program, such as a software application or an operating system, fails to function correctly. If a program experiences a crash, it often automatically exits. The program responsible may appear to freeze or hang until a crash reporting service reports the crash and any details relating to it. If the program is a critical part of the operating system, the entire system may crash or hang, often resulting in a kernel panic or fatal system error.

coding

Coding is representing data and information using code so that it can be processed and analyzed by a computer. Characters, digits, and other objects can be converted into digital code, or information and data can be converted into the required electrical pulse signals based on predefined rules.

encoding technology

A technology that presents data using a specific set of characters, which can be identified by computer hardware and software.

table

A table consists of columns and rows. Each column is referred to as a field. The value in each field represents a data type. For example, if a table contains three fields Name, City, and State, it has three columns Name, City, and State. In every row of the table, the Name column contains a name, the City column contains a city, and the State column contains a state.

tablespace

A tablespace is a logically partitioned space of a database and can belong to only one database. All database objects (mainly tables) are stored in the specified tablespace. A tablespace is a logical storage structure that contains tables, indexes, large objects, and long data. A tablespace provides an abstract layer between physical data and logical data, and provides storage space for all database objects. When you create an object, you can specify which tablespace it belongs to.

concurrency control

A DBMS service that ensures data integrity when multiple transactions are concurrently executed in a multi-user environment. In a multi-threaded openGauss environment, concurrency control ensures that database operations are safe and all database transactions remain consistent at any given time.

query

A request sent to the database with the purpose of updating, modifying, querying, or deleting information.

query operator

An iterator or a query tree node, which is a basic unit for the execution of a query. Execution of a query can be split into one or more query operators. Common query operators include scan, join, and aggregation.

durability

One of the ACID properties of a database transaction. After a transaction is complete, the changes made by the transaction to the database are permanently stored in the database and will not be rolled back.

stored procedure

A collection of SQL statements compiled and stored on a server in a large database system that can be executed using an interface (specifying the procedure name and parameters if any) to perform a specific operation.

operating system

An operating system (OS) is loaded by a boot program to a computer to manage other programs in the computer. Other programs are called applications or application programs.

Blob

Acronym for binary large object, a collection of binary data stored in a database. Blobs are typically videos, audio or other multimedia objects.

segment

A segment is a set of extents in a database. The smallest space scope of a database is an extent, which consists of data blocks. One or more segments comprise a tablespace.