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Set of properties that guarantee database transactions are processed reliably. Stands for Atomicity, Consistency, Isolation, Durability.


Atomicity means that database operations are applied following a “all or nothing” rule. A transaction is either fully applied or not at all.


Consistency means that each transaction that modifies the database takes it from one consistent state to another.


Once a transaction is committed, it will remain so.

Foreign Key

A referential constraint between two tables. Example: A purchase order in the purchase_orders table must have been made by a customer that exists in the customers table.


The Isolation requirement means that no transaction can interfere with another.


A Storage Engine for MySQL and derivatives (Percona Server, MariaDB) originally written by Innobase Oy, since acquired by Oracle. It provides ACID compliant storage engine with foreign key support. As of MySQL version 5.5, InnoDB became the default storage engine on all platforms.


Jenkins is a continuous integration system that we use to help ensure the continued quality of the software we produce. It helps us achieve the aims of:

  • no failed tests in trunk on any platform,

  • aid developers in ensuring merge requests build and test on all platforms,

  • no known performance regressions (without a damn good explanation).


Log Serial Number. A term used in relation to the InnoDB or XtraDB storage engines.


A fork of MySQL that is maintained primarily by Monty Program AB. It aims to add features, fix bugs while maintaining 100% backwards compatibility with MySQL.


The file name of the default MySQL configuration file.


A MySQL storage engine that was the default until MySQL 5.5.


An open source database that has spawned several distributions and forks. MySQL AB was the primary maintainer and distributor until bought by Sun Microsystems, which was then acquired by Oracle. As Oracle owns the MySQL trademark, the term MySQL is often used for the Oracle distribution of MySQL as distinct from the drop-in replacements such as MariaDB and Percona Server.


Non-Uniform Memory Access (NUMA) is a computer memory design used in multiprocessing, where the memory access time depends on the memory location relative to a processor. Under NUMA, a processor can access its own local memory faster than non-local memory, that is, memory local to another processor or memory shared between processors. The whole system may still operate as one unit, and all memory is basically accessible from everywhere, but at a potentially higher latency and lower performance.

Percona Server for MySQL

Percona’s branch of MySQL with performance and management improvements.

Storage Engine

A Storage Engine is a piece of software that implements the details of data storage and retrieval for a database system. This term is primarily used within the MySQL ecosystem due to it being the first widely used relational database to have an abstraction layer around storage. It is analogous to a Virtual File System layer in an Operating System. A VFS layer allows an operating system to read and write multiple file systems (e.g. FAT, NTFS, XFS, ext3) and a Storage Engine layer allows a database server to access tables stored in different engines (e.g. MyISAM, InnoDB).


Percona’s improved version of InnoDB providing performance, features and reliability above what is shipped by Oracle in InnoDB.

Last update: 2022-09-27