K – O
KMC
Acronym for key management component.
KMS
Acronym for key management service.
KSF
Acronym for key store file.
logical replication
Data synchronization mode between primary and standby database nodes or between two databases. Different from physical replication which replays physical logs, logical replication transfers logical logs between two databases or synchronizes data through SQL statements in logical logs.
logical log
Logs recording database changes made through SQL statements. Generally, the changes are logged at the row level. Logical logs are different from physical logs that record changes of physical pages.
logical decoding
Logic decoding is a process of extracting all permanent changes in database tables into a clear and easy-to-understand format by decoding Xlogs.
logical replication slot
In a logical replication process, logic replication slots are used to prevent Xlogs from being reclaimed by the system or VACCUM. A logical replication slot in openGauss is an object that records logical decoding positions. It can be created, deleted, read, and pushed by invoking SQL functions.
MVCC
Acronym for multi-version concurrency control. It is a protocol that allows a tuple to have multiple versions, on which different query operations can be performed. One advantage is that read and write operations do not conflict.
NameNode
NameNode is the centerpiece of an HDFS, managing the namespace of the file system and client access to files.
OM
Acronym for operations management. It provides management interfaces and tools for routine maintenance and configuration management of the database.
client
A program that corresponds to a server and provides local services.
free space management
A mechanism for managing free space in a table. This mechanism enables the database system to record free space in each table and establish an easy-to-find data structure, accelerating operations (such as INSERT) performed on the free space.
junk tuple
A tuple that is deleted using the DELETE and UPDATE statements. When deleting a tuple, openGauss only marks the tuples that are to be cleared. The VACUUM thread will then periodically clear these junk tuples.
column
An equivalent concept of field. A database table consists of one or more columns.
logical node
Multiple logical nodes can be installed on the same physical node. A logical node is a database instance.
schema
Collection of database objects, including logical structures, such as tables, views, sequences, stored procedures, synonyms, indexes, and database links.
schema file
An SQL file that determines the database structure.
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