Incompatibilities and Feature Differences Between MariaDB Rolling and MySQL 8.0

MariaDB maintains high levels of compatibility with MySQL, and most applications that use MySQL will work seamlessly with MariaDB. However, take note of the following incompatibilities and feature differences between MariaDB Rolling Release and MySQL 8.0. It is based on the versions MySQL 8.0.36 and MariaDB 11.7.0. Note that MySQL 8 is an 'evergreen' release, so features may be added or removed in later releases.

Storage Engines

In addition to the standard InnoDB, MyISAM, BLACKHOLE, CSV, MEMORY, ARCHIVE, and MERGE storage engines, the following are also available with MariaDB Rolling:

• ColumnStore utilizes a massively parallel distributed data architecture and is designed for big data scaling to process petabytes of data.
• MyRocks, a storage engine with great compression
• S3 storage engine allows one to archive MariaDB tables in Amazon S3, or any third-party public or private cloud that implements S3 API.
• Aria, MyISAM replacement with better caching.
• CONNECT
• SEQUENCE
• Spider
• SphinxSE
• FederatedX (drop-in replacement for Federated)
• OQGRAPH

Extensions and New Features

The most notable features available in MariaDB, but not in MySQL, are:

• MariaDB Vectors allow MariaDB to perform as a relational vector database.
• Galera is a standard part of MariaDB Server.
• Temporal data tables in the form of:
  • System-versioned tables (allow you to query and operate on historic data).
  • Application-time periods (allow you to query and operate on a temporal range of data), including the WITHOUT OVERLAPS clause.
  • Bitemporal tables (which combine both system-versioning and application-time periods).
• DML-only flashback, allowing instances, databases or tables to be rolled back to an old snapshot.
• Oracle compatibility mode
• MariaDB supports localization in a number of additional languages: Bulgarian, Chinese, Georgian, Hindi, Serbian, and Ukrainian.
• MariaDB has made major improvements to the optimizer.
• Sequences
• Table Value Constructors
• Dynamic Columns support
• Semi-sync plugin merged into the server
• OR REPLACE syntax for CREATE statements, such as CREATE OR REPLACE TABLE, CREATE OR REPLACE DATABASE, etc
• DELETE ... RETURNING, INSERT ... RETURNING, REPLACE ... RETURNING
• GRANT to PUBLIC - MDEV-5215 (blog post)
• PARSEC authentication plugin
• WAIT syntax for setting the lock wait timeout.
• UUID data type for storing UUIDs.
• INET6 and INET4 data types for storing IPv6 and IPv4 addresses.
• SUPER privileges made more granular.
• PROXY protocol support
• Multiple compression algorithms available as plugins
• Number of supported decimals in DECIMAL has increased from 30 to 38
• Number of parts of an index increased from 16 to 32.
• Added catchall for list partitions
• Oracle-style EXECUTE IMMEDIATE statement
• Lots of new JSON functions
• Microsecond Precision in Processlist
• Table Elimination
• Virtual Columns
• Extended User Statistics
• KILL all queries for a user
• Storage-engine-specific CREATE TABLE
• MariaDB supports more collations (506) than MySQL (266).
• FLUSH SSL command to reload SSL certificates without server restart.
• IF NOT EXISTS clause added to INSTALL PLUGIN and IF EXISTS clause added to UNINSTALL PLUGIN and UNINSTALL SONAME
• Enhancements to INFORMATION SCHEMA.PLUGINS table
• Group commit for the binary log. This makes replication notably faster!
• BACKUP STAGE allows one to implement very efficient backups with minimal locking.
• Progress reporting for ALTER TABLE and LOAD DATA INFILE
• SHOW EXPLAIN gives the EXPLAIN plan for a query running in another thread. MySQL introduced the EXPLAIN FOR CONNECTION syntax to do the same thing.
• PCRE Regular Expressions (including REGEXP_REPLACE())
• HandlerSocket and faster HANDLER calls
• MySQL 8 does not support PROCEDURE ANALYSE
• MySQL 8 does not support the use of \N as an alias for NULL
• In MariaDB, it is possible to limit the total size of all temporary files and tables on disk, not just per file.
• On 64-bit platforms, the MariaDB TIMESTAMP was extended to allow values to '2106-02-07 06:28:15 UTC', rather than just '2038-01-19 03:14:07 UTC'.
• MariaDB supports REPAIR TABLE ... FORCE
• Single-table DELETEs support table aliases in MariaDB

Incompatibilities and Differences in Implementation

When moving from MySQL 8.0 to MariaDB Rolling, please take note of the following incompatibilities:

• For a list of function differences, see Function Differences Between MariaDB Rolling and MySQL 8.0
• For a list of system variable differences, see System Variable Differences Between MariaDB Rolling and MySQL 8.0
• MariaDB does not support MySQL's SET PERSIST - MDEV-16228
• MariaDB's GTID is not compatible with MySQL's. Note that MariaDB and MySQL also have different GTID system variables, so these need to be adjusted when migrating.
• The unix_socket authentication plugin is now default on Unix-like systems, which is a major change to authentication in MariaDB. See Authentication from MariaDB 10.4 for an overview of the changes.
• All mysql* binaries are now named mariadb* (the previous mysql named is retained as a symlink for compatibility purposes)
• Not all character sets and collations are supported across both MySQL and MariaDB. As of 11.7, MariaDB supports 40 character sets and 506 collations . As of 8.0.35, MySQL supports 41 character sets (gb18030 being the additional one - MDEV-7495) and 286 collations.
• MariaDB indicates collation pad status as part of the name (e.g. utf8mb3_unicode_nopad_ci), while MySQL indicates pad status by means of an extra column in SHOW COLLATION.
• To make CREATE TABLE ... SELECT work the same way in statement based and row based replication it's by default executed as CREATE OR REPLACE TABLE on the replica. One benefit of this is that if the replica dies in the middle of CREATE ... SELECT it will be able to continue.
  • One can use the slave-ddl-exec-mode variable to specify how CREATE TABLE and DROP TABLE is replicated.
• Users created with MySQL's SHA256 password algorithm cannot be used in MariaDB Rolling - MDEV-9804.
• MariaDB Rollingdoes not support Lateral Derived Tables - MDEV-19078.
• MariaDB Rolling does not support CIDR notation for user accounts - MDEV-25515.
• MariaDB stores JSON as true text, not in binary format as MySQL. MariaDB's JSON functions are much faster than MySQL's so there is no need to store in binary format, which would add complexity when manipulating JSON objects.
• For the same reason, MariaDB's JSON data type is an alias for LONGTEXT. If you want to replicate JSON columns from MySQL to MariaDB, you should store JSON objects in MySQL in a TEXT or LONGTEXT column or use statement-based replication. If you are using JSON columns and want to upgrade to MariaDB, use the mysql_json plugin to automatically convert MySQL JSON to TEXT, or alternatively you need to either convert them to TEXT or use mysqldump to copy these tables to MariaDB.
• In MySQL, JSON is compared according to json values. In MariaDB JSON strings are normal strings and compared as strings.
• MariaDB Rolling does not support MySQL's JSON operators (-> and ->>) - MDEV-13594
• MariaDB Rolling supports the standard by producing null and a warning for JSON_SEARCH when given invalid data, while MySQL produces an error.
• Roles
  • MariaDB never allows authentication via roles, while MySQL permits this.
  • MySQL permits activating multiple roles at the same time. MariaDB can achieve the same result by creating an intermediate aggregate role.
  • In the INFORMATION_SCHEMA.ENABLED_ROLES table, MySQL reports just the direct list of enabled roles, while MariaDB reports the enabled role, plus the effective inherited roles.
  • MySQL extends the INFORMATION_SCHEMA.APPLICABLE_ROLES table .
  • MySQL includes the tables INFORMATION_SCHEMA.ROLE_TABLE_GRANTS, INFORMATION_SCHEMA.ROLE_ROUTINE_GRANTS, INFORMATION_SCHEMA.ROLE_COLUMN_GRANTS, and INFORMATION_SCHEMA ADMINISTRABLE_ROLE_AUTHORIZATIONS.
• MySQL has the performance schema enabled by default. For performance reasons MariaDBRolling has it disabled by default. You can enable it by starting mariadbd with the option --performance-schema.
• MariaDB has removed the InnoDB Change Buffer.
• In MariaDB Rolling, using FLUSH TABLES without any table list will only close tables not in use, and tables not locked by the FLUSH TABLES connection. If there are no locked tables, FLUSH TABLES will be instant and will not cause any waits, as it no longer waits for tables in use. When a table list is provided, the server will wait for the end of any transactions that are using the tables. In MySQL, FLUSH TABLES only waits for the statements to complete.
• MariaDB binaries (mariadbd, myisamchk etc.) give a warning if one uses a unique prefix of an option (such as --big-table instead of --big-tables). MySQL binaries require the full option name.
• MariaDB Rolling implements InnoDB encryption in a different way to MySQL 8.0.
• MySQL's implementation of aborting statements that exceed a certain time to execute can only kill SELECTs, while MariaDB's can kill any queries (excluding stored procedures).
• MariaDB Rolling does not support MySQL's SELECT /*+ MAX_EXECUTION_TIME(n) */ ... - see Aborting Statements that Exceed a Certain Time to Execute.
• MySQL 8.0 does not support the Query Cache.
• MariaDB Rolling does not support the MySQL Memcached plugin (which has been deprecated in MySQL 8.0). However, data stored using memcached can be retrieved because the data is stored as InnoDB tables. MariaDB is able to start successfully with an error message of not being able to find libmemcached.so library.
• In MySQL, X'HHHH', the standard SQL syntax for binary string literals, erroneously works in the same way as 0xHHHH, which could work as a number or string depending on the context. In MariaDB, this has been fixed to behave as a string in all contexts (and never as a number). See CAST and Hexadecimal Literals for more details and examples.
• In MariaDB Rolling, SHOW CREATE TABLE does not quote the DEFAULT value of an integer. MariaDB 10.2 and earlier, and MySQL, do. Since MariaDB can support defaults for BLOB and TEXT fields, while MySQL does not, SHOW CREATE TABLE will also append DEFAULT NULL where no default is explicitly provided to nullable BLOB or TEXT fields in MariaDB.
• As a result of implementing Table Value Constructors, the VALUES function has been renamed to VALUE().
• MariaDB's NOWAIT supports SELECT statements, LOCK TABLES and various DDL statements, while MySQL's NOWAIT only supports SELECT.
• MariaDB's NOWAIT cannot be added on views and stored procedures while MySQL's can - MDEV-25247
• MariaDB does not support RENAME table while it is write-locked - MDEV-30814
• MariaDB returns an ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction when unable to lock within the time, while MySQL returns ERROR 3572 (HY000): Statement aborted because lock(s) could not be acquired immediately and NOWAIT is set
• MariaDB does not support the optional init_vector argument for AES_ENCRYPT and AES_DECRYPT or the block_encryption_mode variable - MDEV-9069
• MariaDB does not support the --initialize option. Use mariadb-install-db instead. - MDEV-19010
• MariaDB Rolling does not support the ngram and MeCab full-text parser plugins - MDEV-10267, MDEV-10268.
• MariaDB Rolling does not support the MySQL X plugin.
• MariaDB Rolling does not support CREATE TABLESPACE for InnoDB.
• The MySQL 8.0 and MariaDB Rolling INFORMATION_SCHEMA.COLUMNS table contain slightly different fields.
• MariaDB Rolling client executables allow the connection protocol to be forced by specifying only connection properties on the command-line. See mariadb Command-line client
• The MySQL binary log includes the thread_id, while MariaDB's binary log does not - MDEV-7850
• The MariaDB syntax supporting Spatial Reference System IDs for spatial data type columns with REF_SYSTEM_ID is not supported by MySQL. MySQL 8 introduced CREATE SPATIAL REFERENCE SYSTEM, which is not supported by MariaDB - MDEV-29953
• MariaDB Rolling does not support the RESTART statement - MDEV-30813
• Compressing the binary log in MariaDB uses a different compression algorithm, and different system variables to manage.
• MariaDB Rolling does not support the SELECT FOR UPDATE and FOR SHARE locks - MDEV-17514

For protocol differences, see MariaDB protocol difference with MySQL.