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Each table with the CSV Storage Engine has .CSM file which contains the metadata of it.


Each table with the CSV Storage engine has .CSV file which contains the data of it (which is a standard Comma Separated Value file).


Files with the .exp extension are created by Percona XtraBackup per each InnoDB tablespace when the --export option is used on prepare. See restore individual tables.


For each table, the server will create a file with the .frm extension containing the table definition (for all storage engines).

General availability (GA)

A finalized version of the product which is made available to the general public. It is the final stage in the software release cycle.


On a multiple tablespace setup ([innodb_file_per_table] enabled), MySQL will store each newly created table on a file with a .ibd extension.


Each table using the MERGE storage engine, besides of a .frm file, will have .MRG file containing the names of the MyISAM tables associated with it.


Each MyISAM table has .MYD (MYData) file which contains the data on it.


Each MyISAM table has .MYI (MYIndex) file which contains the table’s indexes.


MySQL stores options of a database (like charset) in a file with a .opt extension in the database directory.


Each partitioned table has .par file which contains metadata about the partitions.


The file contains the triggers associated with a table, for example, \mytable.TRG. With the .TRN file, they represent all the trigger definitions.


The file contains the names of triggers that are associated with a table, for example, \mytable.TRN. With the .TRG file, they represent all the trigger definitions.


The process of copying data or tables to be stored in a different location.


The method that produces backups in a reduced size.

configuration file

The file that contains the server startup options.


An unexpected shutdown which does not allow the normal server shutdown cleanup activities.

crash recovery

The actions that occur when MySQL is restarted after a crash.

data dictionary

The metadata for the tables, indexes, and table columns stored in the InnoDB system tablespace.


The directory in which the database server stores its data files. Most Linux distribution use /var/lib/mysql by default.

full backup

A backup that contains the complete source data from an instance.


The default prefix for tablespace files. For example, ibdata1 is a 10MB auto-extensible file that MySQL creates for a shared tablespace by default.

incremental backup

A backup stores data from a specific point in time.


Storage engine which provides ACID-compliant transactions and foreign key support, among others improvements over MyISAM. It is the default engine for MySQL 8.3.


The size in bytes of the memory buffer to cache data and indexes of InnoDB’s tables. This aims to reduce disk access to provide better performance.



The directory (relative to datadir) where the database server stores the files in a shared tablespace setup. This option does not affect the location of innodb\_file\_per\_table. For example:

innodb_data_home_dir = ./


Specifies the names, sizes and location of shared tablespace files:



By default, InnoDB creates tables and indexes in a file-per-tablespace. If the innodb_file_per_table variable is disabled, you can enable the variable in your configuration file:

start the server with --innodb_file_per_table.


Specifies the location of the InnoDB log files:


logical backup

A backup which contains a set of SQL statements. The statements can be used to recreate the databases.


Each InnoDB page contains a log sequence number(LSN). The LSN is the system version number for the database. Each page’s LSN shows how recently it was changed.


The database server’s main configuration file. Most Linux distributions place it as /etc/mysql/my.cnf or /etc/my.cnf, but the location and name depends on the particular installation. Note that this method is not the only way of configuring the server, some systems rely on the command options.


The MySQL default storage engine until version 5.5. It doesn’t fully support transactions but in some scenarios may be faster than InnoDB. Each table is stored on disk in 3 files: .frm, .MYD, .MYI.

physical backup

A backup that copies the data files.

point in time recovery

This method restores the data into the state it was at any selected point of time.

prepared backup

A consistent set of backup data that is ready to be restored.


Copies the database backups taken using the backup command to the original location or a different location. A restore returns data that has been either lost, corrupted, or stolen to the original condition at a specific point in time.

Tech preview

A tech preview item can be a feature, a variable, or a value within a variable. Before using this feature in production, we recommend that you test restoring production from physical backups in your environment and also use an alternative backup method for redundancy. A tech preview item is included in a release for users to provide feedback. The item is either updated and released as general availability(GA) or removed if not useful. The functionality can change from tech preview to GA.


To support the encryption and the decryption of the backups. This utility has been modeled after the xbstream binary to perform encryption and decryption outside Percona XtraBackup.


To support simultaneous compression and streaming, Percona XtraBackup uses the xbstream format. For more information see xbstream


Percona XtraDB is an enhanced version of the InnoDB storage engine, designed to better scale on modern hardware. Percona XtraDB includes features which are useful in a high performance environment. It is fully backward-compatible, and is a drop-in replacement for the standard InnoDB storage engine. For more information, see The Percona XtraDB Storage Engine.

Zstandard (ZSTD)

ZSTD is a fast lossless compression algorithm that targets real-time compression scenarios and better compression ratios.

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Last update: 2024-06-12