Data dictionary.  MySQL now incorporates a transactional data dictionary that stores information about database objects. In previous MySQL releases, dictionary data was stored in metadata files and nontransactional tables. For more information, see Chapter 16, MySQL Data Dictionary.

Atomic data definition statements (Atomic DDL).  An atomic DDL statement combines the data dictionary updates, storage engine operations, and binary log writes associated with a DDL operation into a single, atomic transaction. For more information, see Section 15.1.1, “Atomic Data Definition Statement Support”.

Upgrade procedure.  Previously, after installation of a new version of MySQL, the MySQL server automatically upgrades the data dictionary tables at the next startup, after which the DBA is expected to invoke mysql_upgrade manually to upgrade the system tables in the mysql schema, as well as objects in other schemas such as the sys schema and user schemas.

As of MySQL 8.0.16, the server performs the tasks previously handled by mysql_upgrade. After installation of a new MySQL version, the server now automatically performs all necessary upgrade tasks at the next startup and is not dependent on the DBA invoking mysql_upgrade. In addition, the server updates the contents of the help tables (something mysql_upgrade did not do). A new --upgrade server option provides control over how the server performs automatic data dictionary and server upgrade operations. For more information, see Section 3.4, “What the MySQL Upgrade Process Upgrades”.

Session Reuse.  MySQL Server now supports SSL session reuse by default with a timeout setting to control how long the server maintains a session cache that establishes the period during which a client is permitted to request session reuse for new connections. All MySQL client programs support session reuse. For server-side and client-side configuration information, see Section 8.3.5, “Reusing SSL Sessions”.

In addition, C applications now can use the C API capabilities to enable session reuse for encrypted connections (see SSL Session Reuse).

Security and account management.  These enhancements were added to improve security and enable greater DBA flexibility in account management:

Resource management.  MySQL now supports creation and management of resource groups, and permits assigning threads running within the server to particular groups so that threads execute according to the resources available to the group. Group attributes enable control over its resources, to enable or restrict resource consumption by threads in the group. DBAs can modify these attributes as appropriate for different workloads. Currently, CPU time is a manageable resource, represented by the concept of “virtual CPU” as a term that includes CPU cores, hyperthreads, hardware threads, and so forth. The server determines at startup how many virtual CPUs are available, and database administrators with appropriate privileges can associate these CPUs with resource groups and assign threads to groups. For more information, see Section 7.1.16, “Resource Groups”.

Table encryption management.  Table encryption can now be managed globally by defining and enforcing encryption defaults. The default_table_encryption variable defines an encryption default for newly created schemas and general tablespace. The encryption default for a schema can also be defined using the DEFAULT ENCRYPTION clause when creating a schema. By default, a table inherits the encryption of the schema or general tablespace it is created in. Encryption defaults are enforced by enabling the table_encryption_privilege_check variable. The privilege check occurs when creating or altering a schema or general tablespace with an encryption setting that differs from the default_table_encryption setting, or when creating or altering a table with an encryption setting that differs from the default schema encryption. The TABLE_ENCRYPTION_ADMIN privilege permits overriding default encryption settings when table_encryption_privilege_check is enabled. For more information, see Defining an Encryption Default for Schemas and General Tablespaces.

InnoDB enhancements.  These InnoDB enhancements were added:

Character set support.  The default character set has changed from latin1 to utf8mb4. The utf8mb4 character set has several new collations, including utf8mb4_ja_0900_as_cs, the first Japanese language-specific collation available for Unicode in MySQL. For more information, see Section 12.10.1, “Unicode Character Sets”.

JSON enhancements.  The following enhancements or additions were made to MySQL's JSON functionality:

Data type support.  MySQL now supports use of expressions as default values in data type specifications. This includes the use of expressions as default values for the BLOB, TEXT, GEOMETRY, and JSON data types, which previously could not be assigned default values at all. For details, see Section 13.6, “Data Type Default Values”.

Optimizer.  These optimizer enhancements were added:

Common table expressions.  MySQL now supports common table expressions, both nonrecursive and recursive. Common table expressions enable use of named temporary result sets, implemented by permitting a WITH clause preceding SELECT statements and certain other statements. For more information, see Section 15.2.20, “WITH (Common Table Expressions)”.

As of MySQL 8.0.19, the recursive SELECT part of a recursive common table expression (CTE) supports a LIMIT clause. LIMIT with OFFSET is also supported. See Recursive Common Table Expressions, for more information.

Window functions.  MySQL now supports window functions that, for each row from a query, perform a calculation using rows related to that row. These include functions such as RANK(), LAG(), and NTILE(). In addition, several existing aggregate functions now can be used as window functions (for example, SUM() and AVG()). For more information, see Section 14.20, “Window Functions”.

Lateral derived tables.  A derived table now may be preceded by the LATERAL keyword to specify that it is permitted to refer to (depend on) columns of preceding tables in the same FROM clause. Lateral derived tables make possible certain SQL operations that cannot be done with nonlateral derived tables or that require less-efficient workarounds. See Section 15.2.15.9, “Lateral Derived Tables”.

Aliases in single-table DELETE statements.  In MySQL 8.0.16 and later, single-table DELETE statements support the use of table aliases.

Regular expression support.  Previously, MySQL used the Henry Spencer regular expression library to support regular expression operators (REGEXP, RLIKE). Regular expression support has been reimplemented using International Components for Unicode (ICU), which provides full Unicode support and is multibyte safe. The REGEXP_LIKE() function performs regular expression matching in the manner of the REGEXP and RLIKE operators, which now are synonyms for that function. In addition, the REGEXP_INSTR(), REGEXP_REPLACE(), and REGEXP_SUBSTR() functions are available to find match positions and perform substring substitution and extraction, respectively. The regexp_stack_limit and regexp_time_limit system variables provide control over resource consumption by the match engine. For more information, see Section 14.8.2, “Regular Expressions”. For information about ways in which applications that use regular expressions may be affected by the implementation change, see Regular Expression Compatibility Considerations.

One effect of this change is that [a-zA-Z] and [0-9] perform much better in MySQL 8.0 than [[:alpha:]] and [[:digit:]], respectively. Existing applications that use the character classes in pattern matching should be upgraded to use the ranges instead.

Internal temporary tables.  The TempTable storage engine replaces the MEMORY storage engine as the default engine for in-memory internal temporary tables. The TempTable storage engine provides efficient storage for VARCHAR and VARBINARY columns. The internal_tmp_mem_storage_engine session variable defines the storage engine for in-memory internal temporary tables. Permitted values are TempTable (the default) and MEMORY. The temptable_max_ram variable defines the maximum amount of memory that the TempTable storage engine can use before data is stored to disk.

Logging.  These enhancements were added to improve logging:

Backup lock.  A new type of backup lock permits DML during an online backup while preventing operations that could result in an inconsistent snapshot. The new backup lock is supported by LOCK INSTANCE FOR BACKUP and UNLOCK INSTANCE syntax. The BACKUP_ADMIN privilege is required to use these statements.

Replication.  The following enhancements have been made to MySQL Replication:

Connection management.  MySQL Server now permits a TCP/IP port to be configured specifically for administrative connections. This provides an alternative to the single administrative connection that is permitted on the network interfaces used for ordinary connections even when max_connections connections are already established. See Section 7.1.12.1, “Connection Interfaces”.

MySQL now provides more control over the use of compression to minimize the number of bytes sent over connections to the server. Previously, a given connection was either uncompressed or used the zlib compression algorithm. Now, it is also possible to use the zstd algorithm, and to select a compression level for zstd connections. The permitted compression algorithms can be configured on the server side, as well as on the connection-origination side for connections by client programs and by servers participating in source/replica replication or Group Replication. For more information, see Section 6.2.8, “Connection Compression Control”.

Configuration.  The maximum permitted length of host names throughout MySQL has been raised to 255 ASCII characters, up from the previous limit of 60 characters. This applies to, for example, host name-related columns in the data dictionary, mysql system schema, Performance Schema, INFORMATION_SCHEMA, and sys schema; the MASTER_HOST value for the CHANGE MASTER TO statement; the Host column in SHOW PROCESSLIST statement output; host names in account names (such as used in account-management statements and in DEFINER attributes); and host name-related command options and system variables.

Caveats:

Plugins.  Previously, MySQL plugins could be written in C or C++. MySQL header files used by plugins now contain C++ code, which means that plugins must be written in C++, not C.

C API.  The MySQL C API now supports asynchronous functions for nonblocking communication with the MySQL server. Each function is the asynchronous counterpart to an existing synchronous function. The synchronous functions block if reads from or writes to the server connection must wait. The asynchronous functions enable an application to check whether work on the server connection is ready to proceed. If not, the application can perform other work before checking again later. See C API Asynchronous Interface.

Additional target types for casts.  The functions CAST() and CONVERT() now support conversions to types DOUBLE, FLOAT, and REAL. Added in MySQL 8.0.17. See Section 14.10, “Cast Functions and Operators”.

JSON schema validation.  MySQL 8.0.17 adds two functions JSON_SCHEMA_VALID() and JSON_SCHEMA_VALIDATION_REPORT() for validating JSON documents again JSON schemas. JSON_SCHEMA_VALID() returns TRUE (1) if the document validates against the schema and FALSE (0) if it does not. JSON_SCHEMA_VALIDATION_REPORT() returns a JSON document containing detailed information about the results of the validation. The following statements apply to both of these functions:

See Section 14.17.7, “JSON Schema Validation Functions”, for more information and examples.

Multi-valued indexes.  Beginning with MySQL 8.0.17, InnoDB supports the creation of a multi-valued index, which is a secondary index defined on a JSON column that stores an array of values and which can have multiple index records for a single data record. Such an index uses a key part definition such as CAST(data->'$.zipcode' AS UNSIGNED ARRAY). A multi-valued index is used automatically by the MySQL optimizer for suitable queries, as can be viewed in the output of EXPLAIN.

As part of this work, MySQL adds a new function JSON_OVERLAPS() and a new MEMBER OF() operator for working with JSON documents, additionally extending the CAST() function with a new ARRAY keyword, as described in the following list:

For detailed information about multi-valued indexes, including examples, see Multi-Valued Indexes. Section 14.17.3, “Functions That Search JSON Values”, provides information about JSON_OVERLAPS() and MEMBER OF(), along with examples of use.

Hintable time_zone.  As of MySQL 8.0.17, the time_zone session variable is hintable using SET_VAR.

Redo Log Archiving.  As of MySQL 8.0.17, InnoDB supports redo log archiving. Backup utilities that copy redo log records may sometimes fail to keep pace with redo log generation while a backup operation is in progress, resulting in lost redo log records due to those records being overwritten. The redo log archiving feature addresses this issue by sequentially writing redo log records to an archive file. Backup utilities can copy redo log records from the archive file as necessary, thereby avoiding the potential loss of data. For more information, see Redo Log Archiving.

The Clone Plugin.  As of MySQL 8.0.17, MySQL provides a clone plugin that permits cloning InnoDB data locally or from a remote MySQL server instance. A local cloning operation stores cloned data on the same server or node where the MySQL instance runs. A remote cloning operation transfers cloned data over the network from a donor MySQL server instance to the recipient server or node where the cloning operation was initiated.

The clone plugin supports replication. In addition to cloning data, a cloning operation extracts and transfers replication coordinates from the donor and applies them on the recipient, which enables using the clone plugin for provisioning Group Replication members and replicas. Using the clone plugin for provisioning is considerably faster and more efficient than replicating a large number of transactions. Group Replication members can also be configured to use the clone plugin as an alternative method of recovery, so that members automatically choose the most efficient way to retrieve group data from seed members.

For more information, see Section 7.6.7, “The Clone Plugin”, and Section 20.5.4.2, “Cloning for Distributed Recovery”.

As of MySQL 8.0.27, concurrent DDL operations on the donor MySQL Server instance are permitted while a cloning operation is in progress. Previously, a backup lock was held during the cloning operation, preventing concurrent DDL on the donor. To revert to the previous behavior of blocking concurrent DDL on the donor during a clone operation, enable the clone_block_ddl variable. See Section 7.6.7.4, “Cloning and Concurrent DDL”.

As of MySQL 8.0.29, the clone_delay_after_data_drop variable permits specifying a delay period immediately after removing existing data on the recipient MySQL Server instance at the start of a remote cloning operation. The delay is intended to provide enough time for the file system on the recipient host to free space before data is cloned from the donor MySQL Server instance. Certain file systems free space asynchronously in a background process. On these file systems, cloning data too soon after dropping existing data can result in clone operation failures due to insufficient space. The maximum delay period is 3600 seconds (1 hour). The default setting is 0 (no delay).

As of MySQL 8.0.37, cloning is allowed between different point releases. In other words, only the major and minor version numbers must match when previously the point release number also had to match.

For example, clone functionality now permits cloning 8.0.37 to 8.0.41 or 8.0.51 to 8.0.39. Previous restrictions still apply to versions older than 8.0.37, so cloning the likes of 8.0.36 to 8.0.42 or vice-versa is not permitted.

Hash Join Optimization.  Beginning with MySQL 8.0.18, a hash join is used whenever each pair of tables in a join includes at least one equi-join condition, and no indexes apply to any join condition. A hash join does not require indexes, although it can be used with indexes applying to single-table predicates only. A hash join is more efficient in most cases than the block-nested loop algorithm. Joins such as those shown here can be optimized in this manner:

SELECT *
    FROM t1
    JOIN t2
        ON t1.c1=t2.c1;

SELECT *
    FROM t1
    JOIN t2
        ON (t1.c1 = t2.c1 AND t1.c2 < t2.c2)
    JOIN t3
        ON (t2.c1 = t3.c1)

Hash joins can also be used for Cartesian products—that is, when no join condition is specified.

You can see when the hash join optimization is being used for a particular query using EXPLAIN FORMAT=TREE or EXPLAIN ANALYZE. (In MySQL 8.0.20 and later, you can also use EXPLAIN, omitting FORMAT=TREE.)

The amount of memory available to a hash join is limited by the value of join_buffer_size. A hash join that requires more than this much memory is executed on disk; the number of disk files that can be used by an on-disk hash join is limited by open_files_limit.

As of MySQL 8.0.19, the hash_join optimizer switch which was introduced in MySQL 8.0.18 no longer supported (hash_join=on still appears as part of the value of optimizer_switch, but setting it no longer has any effect). The HASH_JOIN and NO_HASH_JOIN optimizer hints are also no longer supported. The switch and the hint are both now deprecated; expect them to be removed in a future MySQL release. In MySQL 8.0.18 and later, hash joins can be disabled using the NO_BNL optimizer switch.

In MySQL 8.0.20 and later, block nested loop is no longer used in the MySQL server, and a hash join is employed any time a block nested loop would have been used previously, even when the query contains no equi-join conditions. This applies to inner non-equijoins, semijoins, antijoins, left outer joins, and right outer joins. The block_nested_loop flag for the optimizer_switch system variable as well as the BNL and NO_BNL optimizer hints are still supported, but henceforth control use of hash joins only. In addition, both inner and outer joins (including semijoins and antijoins) can now employ batched key access (BKA), which allocates join buffer memory incrementally so that individual queries need not use up large amounts of resources that they do not actually require for resolution. BKA for inner joins only is supported starting with MySQL 8.0.18.

MySQL 8.0.20 also replaces the executor used in previous versions of MySQL with the iterator executor. This work includes replacement of the old index subquery engines that governed queries of the form WHERE value IN (SELECT column FROM table WHERE ...) for those IN queries which have not been optimized as semijoins, as well as queries materialized in the same form, which formerly depended on the old executor.

For more information and examples, see Section 10.2.1.4, “Hash Join Optimization”. See also Batched Key Access Joins.

EXPLAIN ANALYZE Statement.  A new form of the EXPLAIN statement, EXPLAIN ANALYZE, is implemented in MySQL 8.0.18, providing expanded information about the execution of SELECT statements in TREE format for each iterator used in processing the query, and making it possible to compare estimated cost with the actual cost of the query. This information includes startup cost, total cost, number of rows returned by this iterator, and the number of loops executed.

In MySQL 8.0.21 and later, this statement also supports a FORMAT=TREE specifier. TREE is the only supported format.

See Obtaining Information with EXPLAIN ANALYZE, for more information.

Query cast injection.  In version 8.0.18 and later, MySQL injects cast operations into the query item tree inside expressions and conditions in which the data type of the argument and the expected data type do not match. This has no effect on query results or speed of execution, but makes the query as executed equivalent to one which is compliant with the SQL standard while maintaining backwards compatibility with previous releases of MySQL.

Such implicit casts are now performed between temporal types (DATE, DATETIME, TIMESTAMP, TIME) and numeric types (SMALLINT, TINYINT, MEDIUMINT, INT/INTEGER, BIGINT; DECIMAL/NUMERIC; FLOAT, DOUBLE, REAL; BIT) whenever they are compared using any of the standard numeric comparison operators (=, >=, >, <, <=, <>/!=, or <=>). In this case, any value that is not already a DOUBLE is cast as one. Cast injection is also now performed for comparisons between DATE or TIME values and DATETIME values, where the arguments are cast whenever necessary as DATETIME.

Beginning with MySQL 8.0.21, such casts are also performed when comparing string types with other types. String types that are cast include CHAR, VARCHAR, BINARY, VARBINARY, BLOB, TEXT, ENUM, and SET. When comparing a value of a string type with a numeric type or YEAR, the string cast is to DOUBLE; if the type of the other argument is not FLOAT, DOUBLE, or REAL, it is also cast to DOUBLE. When comparing a string type to a DATETIME or TIMESTAMP value, the string is cast is to DATETIME; when comparing a string type with DATE, the string is cast to DATE.

It is possible to see when casts are injected into a given query by viewing the output of EXPLAIN ANALYZE, EXPLAIN FORMAT=JSON, or, as shown here, EXPLAIN FORMAT=TREE:

mysql> CREATE TABLE d (dt DATETIME, d DATE, t TIME);
Query OK, 0 rows affected (0.62 sec)

mysql> CREATE TABLE n (i INT, d DECIMAL, f FLOAT, dc DECIMAL);
Query OK, 0 rows affected (0.51 sec)

mysql> CREATE TABLE s (c CHAR(25), vc VARCHAR(25),
    ->     bn BINARY(50), vb VARBINARY(50), b BLOB, t TEXT,
    ->     e ENUM('a', 'b', 'c'), se SET('x' ,'y', 'z'));
Query OK, 0 rows affected (0.50 sec)

mysql> EXPLAIN FORMAT=TREE SELECT * from d JOIN n ON d.dt = n.i\G
*************************** 1. row ***************************
EXPLAIN: -> Inner hash join (cast(d.dt as double) = cast(n.i as double))
(cost=0.70 rows=1)
    -> Table scan on n  (cost=0.35 rows=1)
    -> Hash
        -> Table scan on d  (cost=0.35 rows=1)

mysql> EXPLAIN FORMAT=TREE SELECT * from s JOIN d ON d.dt = s.c\G
*************************** 1. row ***************************
EXPLAIN: -> Inner hash join (d.dt = cast(s.c as datetime(6)))  (cost=0.72 rows=1)
    -> Table scan on d  (cost=0.37 rows=1)
    -> Hash
        -> Table scan on s  (cost=0.35 rows=1)

1 row in set (0.01 sec)

mysql> EXPLAIN FORMAT=TREE SELECT * from n JOIN s ON n.d = s.c\G
*************************** 1. row ***************************
EXPLAIN: -> Inner hash join (cast(n.d as double) = cast(s.c as double))  (cost=0.70 rows=1)
    -> Table scan on s  (cost=0.35 rows=1)
    -> Hash
        -> Table scan on n  (cost=0.35 rows=1)

1 row in set (0.00 sec)

Such casts can also be seen by executing EXPLAIN [FORMAT=TRADITIONAL], in which case it is also necessary to issue SHOW WARNINGS after executing the EXPLAIN statement.

Time zone support for TIMESTAMP and DATETIME.  As of MySQL 8.0.19, the server accepts a time zone offset with inserted datetime (TIMESTAMP and DATETIME) values. This offset uses the same format as that employed when setting the time_zone system variable, except that a leading zero is required when the hours portion of the offset is less than 10, and '-00:00' is not allowed. Examples of datetime literals that include time zone offsets are '2019-12-11 10:40:30-05:00', '2003-04-14 03:30:00+10:00', and '2020-01-01 15:35:45+05:30'.

Time zone offsets are not displayed when selecting datetime values.

Datetime literals incorporating time zone offsets can be used as prepared statement parameter values.

As part of this work, the value used to set the time_zone system variable is now also restricted to the range -13:59 to +14:00, inclusive. (It remains possible to assign name values to time_zone such as 'EST', 'Posix/Australia/Brisbane', and 'Europe/Stockholm' to this variable, provided that the MySQL time zone tables are loaded; see Populating the Time Zone Tables).

For more information and examples, see Section 7.1.15, “MySQL Server Time Zone Support”, as well as Section 13.2.2, “The DATE, DATETIME, and TIMESTAMP Types”.

Precise information for JSON schema CHECK constraint failures.  When using JSON_SCHEMA_VALID() to specify a CHECK constraint, MySQL 8.0.19 and later provides precise information about the reasons for failures of such constraints.

For examples and more information, see JSON_SCHEMA_VALID() and CHECK constraints. See also Section 15.1.20.6, “CHECK Constraints”.

Row and column aliases with ON DUPLICATE KEY UPDATE.  Beginning with MySQL 8.0.19, it is possible to reference the row to be inserted, and, optionally, its columns, using aliases. Consider the following INSERT statement on a table t having columns a and b:

INSERT INTO t SET a=9,b=5
    ON DUPLICATE KEY UPDATE a=VALUES(a)+VALUES(b);

Using the alias new for the new row, and, in some cases, the aliases m and n for this row's columns, the INSERT statement can be rewritten in many different ways, some examples of which are shown here:

INSERT INTO t SET a=9,b=5 AS new
    ON DUPLICATE KEY UPDATE a=new.a+new.b;

INSERT INTO t VALUES(9,5) AS new
    ON DUPLICATE KEY UPDATE a=new.a+new.b;

INSERT INTO t SET a=9,b=5 AS new(m,n)
    ON DUPLICATE KEY UPDATE a=m+n;

INSERT INTO t VALUES(9,5) AS new(m,n)
    ON DUPLICATE KEY UPDATE a=m+n;

For more information and examples, see Section 15.2.7.2, “INSERT ... ON DUPLICATE KEY UPDATE Statement”.

SQL standard explicit table clause and table value constructor.  Added table value constructors and explicit table clauses according to the SQL standard. These are implemented in MySQL 8.0.19, respectively, as the TABLE statement and the VALUES statement.

The TABLE statement has the format TABLE table_name, and is equivalent to SELECT * FROM table_name. It supports ORDER BY and LIMIT clauses ( the latter with optional OFFSET), but does not allow for the selection of individual table columns. TABLE can be used anywhere that you would employ the equivalent SELECT statement; this includes joins, unions, INSERT ... SELECT, REPLACE, CREATE TABLE ... SELECT statements, and subqueries. For example:

VALUES can be used to supply a table value to an INSERT, REPLACE, or SELECT statement, and consists of the VALUES keyword followed by a series of row constructors (ROW()) separated by commas. For example, the statement INSERT INTO t1 VALUES ROW(1,2,3), ROW(4,5,6), ROW(7,8,9) provides an SQL-compliant equivalent to the MySQL-specific INSERT INTO t1 VALUES (1,2,3), (4,5,6), (7,8,9). You can also select from a VALUES table value constructor just as you would a table, bearing in mind that you must supply a table alias when doing so, and use this SELECT just as you would any other; this includes joins, unions, and subqueries.

For more information about TABLE and VALUES, and for examples of their use, see the following sections of this documentation:

Optimizer hints for FORCE INDEX, IGNORE INDEX.  MySQL 8.0 introduces index-level optimizer hints which serve as analogs to the traditional index hints as described in Section 10.9.4, “Index Hints”. The new hints are listed here, along with their FORCE INDEX or IGNORE INDEX equivalents:

For example, the following two queries are equivalent:

SELECT a FROM t1 FORCE INDEX (i_a) FOR JOIN WHERE a=1 AND b=2;

SELECT /*+ JOIN_INDEX(t1 i_a) */ a FROM t1 WHERE a=1 AND b=2;

The optimizer hints listed previously follow the same basic rules for syntax and usage as existing index-level optimizer hints.

These optimizer hints are intended to replace FORCE INDEX and IGNORE INDEX, which we plan to deprecate in a future MySQL release, and subsequently to remove from MySQL. They do not implement a single exact equivalent for USE INDEX; instead, you can employ one or more of NO_INDEX, NO_JOIN_INDEX, NO_GROUP_INDEX, or NO_ORDER_INDEX to achieve the same effect.

For further information and examples of use, see Index-Level Optimizer Hints.

JSON_VALUE() function.  MySQL 8.0.21 implements a new function JSON_VALUE() intended to simplify indexing of JSON columns. In its most basic form, it takes as arguments a JSON document and a JSON path pointing to a single value in that document, as well as (optionally) allowing you to specify a return type with the RETURNING keyword. JSON_VALUE(json_doc, path RETURNING type) is equivalent to this:

CAST(
    JSON_UNQUOTE( JSON_EXTRACT(json_doc, path) )
    AS type
);

You can also specify ON EMPTY, ON ERROR, or both clauses, similar to those employed with JSON_TABLE().

You can use JSON_VALUE() to create an index on an expression on a JSON column like this:

CREATE TABLE t1(
    j JSON,
    INDEX i1 ( (JSON_VALUE(j, '$.id' RETURNING UNSIGNED)) )
);

INSERT INTO t1 VALUES ROW('{"id": "123", "name": "shoes", "price": "49.95"}');

A query using this expression, such as that shown here, can make use of the index:

SELECT j->"$.name" as name, j->"$.price" as price 
    FROM t1
    WHERE JSON_VALUE(j, '$.id' RETURNING UNSIGNED) = 123;

In many cases, this is simpler than creating a generated column from the JSON column and then creating an index on the generated column.

For more information and examples, see the description of JSON_VALUE().

User comments and user attributes.  MySQL 8.0.21 introduces the ability to set user comments and user attributes when creating or updating user accounts. A user comment consists of arbitrary text passed as the argument to a COMMENT clause used with a CREATE USER or ALTER USER statement. A user attribute consists of data in the form of a JSON object passed as the argument to an ATTRIBUTE clause used with either of these two statements. The attribute can contain any valid key-value pairs in JSON object notation. Only one of COMMENT or ATTRIBUTE can be used in a single CREATE USER or ALTER USER statement.

User comments and user attributes are stored together internally as a JSON object, the comment text as the value of an element having comment as its key. This information can be retrieved from the ATTRIBUTE column of the Information Schema USER_ATTRIBUTES table; since it is in JSON format, you can use MySQL's JSON function and operators to parse its contents (see Section 14.17, “JSON Functions”). Successive changes to the user attribute are merged with its current value as when using the JSON_MERGE_PATCH() function.

Example:

mysql> CREATE USER 'mary'@'localhost' COMMENT 'This is Mary Smith\'s account';
Query OK, 0 rows affected (0.33 sec)

mysql> ALTER USER 'mary'@'localhost'
    -≫     ATTRIBUTE '{"fname":"Mary", "lname":"Smith"}';
Query OK, 0 rows affected (0.14 sec)

mysql> ALTER USER 'mary'@'localhost'
    -≫     ATTRIBUTE '{"email":"mary.smith@example.com"}';
Query OK, 0 rows affected (0.12 sec)

mysql> SELECT
    ->    USER,
    ->    HOST,
    ->    ATTRIBUTE->>"$.fname" AS 'First Name',
    ->    ATTRIBUTE->>"$.lname" AS 'Last Name',
    ->    ATTRIBUTE->>"$.email" AS 'Email',
    ->    ATTRIBUTE->>"$.comment" AS 'Comment'
    -> FROM INFORMATION_SCHEMA.USER_ATTRIBUTES
    -> WHERE USER='mary' AND HOST='localhost'\G
*************************** 1. row ***************************
      USER: mary
      HOST: localhost
First Name: Mary
 Last Name: Smith
     Email: mary.smith@example.com
   Comment: This is Mary Smith's account
1 row in set (0.00 sec)

For more information and examples, see Section 15.7.1.3, “CREATE USER Statement”, Section 15.7.1.1, “ALTER USER Statement”, and Section 28.3.46, “The INFORMATION_SCHEMA USER_ATTRIBUTES Table”.

New optimizer_switch flags.  MySQL 8.0.21 adds two new flags for the optimizer_switch system variable, as described in the following list:

For more information, see Section 10.9.2, “Switchable Optimizations”. See also Section 10.2.1.19, “LIMIT Query Optimization”, Section 10.2.2.1, “Optimizing IN and EXISTS Subquery Predicates with Semijoin Transformations”, and Section 10.2.2.4, “Optimizing Derived Tables, View References, and Common Table Expressions with Merging or Materialization”.

XML enhancements.  As of MySQL 8.0.21, the LOAD XML statement now supports CDATA sections in the XML to be imported.

Casting to the YEAR type now supported.  Beginning with MySQL 8.0.22, the server allows casting to YEAR. Both the CAST() and CONVERT() functions support single-digit, two-digit, and four-digit YEAR values. For one-digit and two-digit values, the allowed range is 0-99. Four-digit values must be in the range 1901-2155. YEAR can also be used as the return type for the JSON_VALUE() function; this function supports four-digit years only.

String, time-and-date, and floating-point values can all be cast to YEAR. Casting of GEOMETRY values to YEAR is not supported.

For more information, including conversion rules, see the description of the CONVERT() function.

Retrieval of TIMESTAMP values as UTC.  MySQL 8.0.22 and later supports conversion of a TIMESTAMP column value from the system time zone to a UTC DATETIME on retrieval, using CAST(value AT TIME ZONE specifier AS DATETIME), where the specifier is one of [INTERVAL] '+00:00' or 'UTC'. The precision of the DATETIME value returned by the cast can be specified up to 6 decimal places, if desired. The ARRAY keyword is not supported with this construct.

TIMESTAMP values inserted into a table using a timezone offset are also supported. Use of AT TIME ZONE is not supported for CONVERT() or any other MySQL function or construct.

For further information and examples, see the description of the CAST() function.

Dump file output synchronization.  MySQL 8.0.22 and later supports periodic synchronization when writing to files by SELECT INTO DUMPFILE and SELECT INTO OUTFILE statements. This can be enabled by setting the select_into_disk_sync system variable to ON; the size of the write buffer is determined by the value set for select_into_buffer_size; the default is 131072 (2¹⁷) bytes.

In addition, an optional delay following synchronization to disk can be set using select_into_disk_sync_delay; the default is no delay (0 milliseconds).

For more information, see the descriptions of the variables referenced previously in this item.

Single preparation of statements.  As of MySQL 8.0.22, a prepared statement is prepared a single time, rather than once each time it is executed. This is done when executing PREPARE. This is also true for any statement inside a stored procedure; the statement is prepared once, when the stored procedure is first executed.

One result of this change is that the fashion in which dynamic parameters used in prepared statements are resolved is also changed in the ways listed here:

Preparing a statement used as a prepared statement or within a stored procedure only once enhances the performance of the statement, since it negates the added cost of repeated preparation. Doing so also avoids possible multiple rollbacks of preparation structures, which has been the source of numerous issues in MySQL.

For more information, see Section 15.5.1, “PREPARE Statement”.

RIGHT JOIN as LEFT JOIN handling.  As of MySQL 8.0.22, the server handles all instances of RIGHT JOIN internally as LEFT JOIN, eliminating a number of special cases in which a complete conversion was not performed at parse time.

Derived condition pushdown optimization.  MySQL 8.0.22 (and later) implements derived condition pushdown for queries having materialized derived tables. For a query such as SELECT * FROM (SELECT i, j FROM t1) AS dt WHERE i > constant, it is now possible in many cases to push the outer WHERE condition down to the derived table, in this case resulting in SELECT * FROM (SELECT i, j FROM t1 WHERE i > constant) AS dt.

Previously, if the derived table was materialized and not merged, MySQL materialized the entire table, then qualified the rows with the WHERE condition. Moving the WHERE condition into the subquery using the derived condition pushdown optimization can often reduce the number of rows must be processed, which can decrease the time needed to execute the query.

An outer WHERE condition can be pushed down directly to a materialized derived table when the derived table does not use any aggregate or window functions. When the derived table has a GROUP BY and does not use any window functions, the outer WHERE condition can be pushed down to the derived table as a HAVING condition. The WHERE condition can also be pushed down when the derived table uses a window function and the outer WHERE references columns used in the window function's PARTITION clause.

Derived condition pushdown is enabled by default, as indicated by the optimizer_switch system variable's derived_condition_pushdown flag. The flag, added in MySQL 8.0.22, is set to on by default; to disable the optimization for a specific query, you can use the NO_DERIVED_CONDITION_PUSHDOWN optimizer hint (also added in MySQL 8.0.22). If the optimization is disabled due to derived_condition_pushdown being set to off, you can enable it for a given query using DERIVED_CONDITION_PUSHDOWN.

The derived condition pushdown optimization cannot be employed for a derived table that contains a LIMIT clause. Prior to MySQL 8.0.29, the optimization also cannot be used when the query contains UNION. In MySQL 8.0.29 and later, conditions can be pushed down to both query blocks of a union in most cases; see Section 10.2.2.5, “Derived Condition Pushdown Optimization”, for more information.

In addition, a condition that itself uses a subquery cannot be pushed down, and a WHERE condition cannot be pushed down to a derived table that is also an inner table of an outer join. For additional information and examples, see Section 10.2.2.5, “Derived Condition Pushdown Optimization”.

Non-locking reads on MySQL grant tables.  As of MySQL 8.0.22, to permit concurrent DML and DDL operations on MySQL grant tables, read operations that previously acquired row locks on MySQL grant tables are executed as non-locking reads.

The operations that are now performed as non-locking reads on MySQL grant tables include:

For additional information, see Grant Table Concurrency.

64-bit support for FROM_UNIXTIME(), UNIX_TIMESTAMP(), CONVERT_TZ().  As of MySQL 8.0.28, the functions FROM_UNIXTIME(), UNIX_TIMESTAMP(), and CONVERT_TZ() handle 64-bit values on platforms that support them. This includes 64-bit versions of Linux, MacOS, and Windows.

On compatible platforms, UNIX_TIMESTAMP() now handles values up to '3001-01-18 23:59:59.999999' UTC, and FROM_UNIXTIME() can convert values up to 32536771199.999999 seconds since the Unix Epoch; CONVERT_TZ() now accepts values that do not exceed '3001-01-18 23:59:59.999999' UTC following conversion.

The behavior of these functions on 32-bit platforms is unaffected by these changes. The behavior of the TIMESTAMP type is also not affected (on any platform); for working with datetimes after '2038-01-19 03:14:07.999999', UTC, use the DATETIME type instead.

For more information, see the descriptions of the individual functions just discussed, in Section 14.7, “Date and Time Functions”.

Resource allocation control.  Beginning with MySQL 8.0.28, you can see the amount of memory used for queries issued by all regular users by checking the Global_connection_memory status variable. (This total does not include resources used by system users such as MySQL root. It is also exclusive of any memory taken by the InnoDB buffer pool.)

To enable updates of Global_connection_memory, it is necessary to set global_connection_memory_tracking = 1; this is 0 (off) by default. You can control how often Global_connection_memory is updated by setting connection_memory_chunk_size.

It is also possible to set memory usage limits for normal users on the session or global level, or both, by setting either or both of the system variables listed here:

These limits do not apply to system processes or administrative accounts.

See the descriptions of the referenced variables for more information.

Detached XA transactions.  MySQL 8.0.29 adds support for XA transactions which, once prepared, are no longer connected to the originating connection. This means that they can be committed or rolled back by another connection, and that the current session can immediately begin another transaction.

A system variable xa_detach_on_prepare controls whether XA transaction are detached; the default is ON, which causes all XA transactions to be detached. Use of temporary tables is disallowed for XA transactions when this is in effect.

For more information, see Section 15.3.8.2, “XA Transaction States”.

Automatic binary log purge control.  MySQL 8.0.29 adds the binlog_expire_logs_auto_purge system variable, which provides a single interface for enabling and disabling automatic purging of the binary logs. This is enabled (ON) by default; to disable automatic purging of the binary log files, set this variable to OFF.

binlog_expire_logs_auto_purge must be ON in order for automatic purging of the binary log files to proceed; the value of this variable takes precedence over that of any other server option or variable, including (but not exclusive to) binlog_expire_logs_seconds.

The setting for binlog_expire_logs_auto_purge has no effect on PURGE BINARY LOGS.

Conditional routine and trigger creation statements.  Beginning with MySQL 8.0.29, the following statements support an IF NOT EXISTS option:

For CREATE FUNCTION when creating a stored function and CREATE PROCEDURE, this option prevents an error from occurring if there is already a routine having the same name. For CREATE FUNCTION when used to create a loadable function, the option prevents an error if there already exists a loadable function having that name. For CREATE TRIGGER, the option prevents an error from occurring if there already exists in the same schema and on the same table a trigger having the same name.

This enhancement aligns the syntax of these statements more closely with that of CREATE DATABASE, CREATE TABLE, CREATE USER, and CREATE EVENT (all of which already support IF NOT EXISTS), and acts to complement the IF EXISTS option supported by DROP PROCEDURE, DROP FUNCTION, and DROP TRIGGER statements.

For more information, see the descriptions of the indicated SQL statements, as well as Function Name Resolution. See also Section 19.5.1.7, “Replication of CREATE TABLE ... SELECT Statements”.

Included FIDO library upgrade.  MySQL 8.0.30 upgrades the included fido2 library (used with the authentication_fido plugin) from version 1.5.0 to version 1.8.0.

See Section 8.4.1.11, “FIDO Pluggable Authentication”, for more information.

Character sets: Language-specific collations.  Previously, when more than one language had the exact same collation definition, MySQL implemented collations for only one of the languages, which meant that some languages were covered only by utf8mb4 Unicode 9.0 collations specific to other languages. MySQL 8.0.30 (and later) fixes such issues by providing language-specific collations for those languages that were previously covered only by language-specific collations for other languages. Languages covered by the new collations are listed here:

MySQL provides *_as_cs and *_ai_ci collations for each of the languages just listed.

For more information, see Language-Specific Collations.

IF EXISTS and IGNORE UNKNOWN USER options for REVOKE.  MySQL 8.0.30 implements two new options for REVOKE which can be used to determine whether a statement yields an error or a warning when a user, role, or privilege specified in the statement cannot be found, or cannot be assigned. Very basic syntax showing the placement of these new options is provided here:

REVOKE [IF EXISTS] privilege_or_role 
    ON object 
    FROM user_or_role [IGNORE UNKNOWN USER]

IF EXISTS causes an unsuccessful REVOKE statement to raise a warning instead of an error, as long as the named target user or role actually exists, despite any references in the statement to any roles or privileges which cannot be found.

IGNORE UNKNOWN USER causes an unsuccessful REVOKE to raise a warning rather than an error when the target user or role named in the statement cannot be found.

For further information and examples, see Section 15.7.1.8, “REVOKE Statement”.

Generated invisible primary keys.  Beginning with MySQL 8.0.30, it is possible to run a replication source server such that a generated invisible primary key (GIPK) is added to any InnoDB table that is created without an explicit primary key. The generated key column definition added to such a table is equivalent to what is shown here:

my_row_id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT INVISIBLE PRIMARY KEY

GIPK mode is not enabled by default. To enable it, set the sql_generate_invisible_primary_key server system variable to ON.

Generated invisible primary keys are normally visible in the output of statements such as SHOW CREATE TABLE and SHOW INDEX, as well as in MySQL Information Schema tables such as the COLUMNS and STATISTICS tables. You can cause them to be hidden in such cases instead, by setting show_gipk_in_create_table_and_information_schema to OFF.

As part of this work, a new --skip-generated-invisible-primary-key option is added to mysqldump and mysqlpump to exclude generated invisible primary keys, columns, and column values from their output.

GIPKs and replication between tables with or without primary keys.  In MySQL Replication, a replica effectively ignores any setting for sql_generate_invisible_primary_key on the source, such that it has no effect on replicated tables. MySQL 8.0.32 and later makes it possible for the replica to add a generated invisible primary key to any InnoDB table that otherwise, as replicated, has no primary key. You can do this by invoking CHANGE REPLICATION SOURCE TO ... REQUIRE_TABLE_PRIMARY_KEY_CHECK = GENERATE on the replica.

REQUIRE_TABLE_PRIMARY_KEY_CHECK = GENERATE is not compatible with MySQL Group Replication.

For further information, see Section 15.1.20.11, “Generated Invisible Primary Keys”.

Crash-safe XA transactions.  Previously, XA transactions were not fully resilient to an unexpected halt with respect to the binary log, and if this occurred while the server was executing XA PREPARE, XA COMMIT, or XA ROLLBACK, the server was not guaranteed to be recoverable to the correct state, possibly leaving the binary log with extra XA transactions that had not been applied, or missing one or more XA transactions that had been applied. Beginning with MySQL 8.0.30, this is no longer an issue, and a server that drops out of a replication topology for whatever reason can always be brought back to a consistent XA transaction state when rejoining.

Known issue: When the same transaction XID is used to execute XA transactions sequentially and a break occurs during the execution of XA COMMIT ... ONE PHASE, using this same XID, after this transaction has been prepared in the storage engine, it may not be possible any longer to synchronize the state between the binary log and the storage engine.

For more information, see Section 15.3.8.3, “Restrictions on XA Transactions”.

Nesting with UNION.  Beginning with MySQL 8.0.31, bodies of parenthesized query expressions can be nested up to 63 levels deep in combination with UNION. Such queries were previously rejected with error ER_NOT_SUPPORTED_YET, but are now allowed. EXPLAIN output for such a query is shown here:

mysql> EXPLAIN FORMAT=TREE ( 
    ->   (SELECT a, b, c FROM t ORDER BY a LIMIT 3) ORDER BY b LIMIT 2
    -> ) ORDER BY c LIMIT 1\G
*************************** 1. row ***************************
EXPLAIN: -> Limit: 1 row(s)  (cost=5.55..5.55 rows=1)
    -> Sort: c, limit input to 1 row(s) per chunk  (cost=2.50 rows=0)
        -> Table scan on <result temporary>  (cost=2.50 rows=0)
            -> Temporary table  (cost=5.55..5.55 rows=1)
                -> Limit: 2 row(s)  (cost=2.95..2.95 rows=1)
                    -> Sort: b, limit input to 2 row(s) per chunk  (cost=2.50 rows=0)
                        -> Table scan on <result temporary>  (cost=2.50 rows=0)
                            -> Temporary table  (cost=2.95..2.95 rows=1)
                                -> Limit: 3 row(s)  (cost=0.35 rows=1)
                                    -> Sort: t.a, limit input to 3 row(s) per chunk  (cost=0.35 rows=1)
                                        -> Table scan on t  (cost=0.35 rows=1)

1 row in set (0.00 sec)

MySQL follows SQL standard semantics when collapsing bodies of parenthesized query expressions, so that a higher outer limit cannot override an inner lower one. For example, (SELECT ... LIMIT 5) LIMIT 10 can return no more than five rows.

The 63-level limit is imposed only after the MySQL Optimizer's parser has performed any simplifications or merges which it can.

For more information, see Section 15.2.11, “Parenthesized Query Expressions”.

Disabling query rewrites.  Previously, when using the Rewriter plugin, all queries were subject to being rewritten, regardless of user. This could be problematic in certain cases, such as when administering the system, or when applying statements originating from a replication source or a dump file created by mysqldump or another MySQL program. MySQL 8.0.31 provides a solution to such issues by implementing a new user privilege SKIP_QUERY_REWRITE; statements issued by a user having this privilege are ignored by Rewriter and not rewritten.

MySQL 8.0.31 also adds a new server system variable rewriter_enabled_for_threads_without_privilege_checks. When set to OFF, rewritable statements issued by threads for which PRIVILEGE_CHECKS_USER is NULL (such as replication applier threads) are not rewritten by the Rewriter plugin. The default is ON, which means such statements are rewritten.

For more information, see Section 7.6.4, “The Rewriter Query Rewrite Plugin”.

Replication filtering of XA statements.  Previously, the statements XA START, XA END, XA COMMIT, and XA ROLLBACK were filtered by the default database whenever using --replicate-do-db or --replicate-ignore-db, which could lead to missed transactions. As of MySQL 8.0.31, these statements are not filtered in such cases, regardless of the value of binlog_format.

Replication filtering and privilege checks.  Beginning with MySQL 8.0.31, when replication filtering is in use, a replica no longer raises replication errors related to privilege checks or require_row_format validation for events which are filtered out, making it possible to filter out any transactions that fail validation.

Because privilege checks on filtered rows can no longer cause replication to stop, a replica can now accept only the portion of a database to which a given user has been granted access; this is true as long as updates to this part of the database are replicated only in row-based format.

This capability may also be of use when migrating to HeatWave Service from an on-premise or cloud service which uses tables for administration or other purposes to which the inbound replication user does not have access.

For more information, see Section 19.2.5, “How Servers Evaluate Replication Filtering Rules”, as well as Section 19.5.1.29, “Replica Errors During Replication”.

INTERSECT and EXCEPT table operators.  MySQL 8.0.31 adds support for the SQL INTERSECT and EXCEPT table operators. Where a and b represent result sets of queries, these operators behave as follows:

INTERSECT DISTINCT, INTERSECT ALL, EXCEPT DISTINCT, and EXCEPT ALL are all supported; DISTINCT is the default for both INTERSECT and EXCEPT (this is the same as for UNION).

For more information and examples, see Section 15.2.8, “INTERSECT Clause”, and Section 15.2.4, “EXCEPT Clause”.

User-defined histograms.  Beginning with MySQL 8.0.31, it is possible to set the histogram of a column to a user-specified JSON value. This can be done using the following SQL syntax:

ANALYZE TABLE tbl_name 
  UPDATE HISTOGRAM ON col_name
  USING DATA 'json_data'

This statement creates or overwrites a histogram for column col_name of table tbl_name using the histogram's JSON representation json_data. After executing this statement, you can verify that the histogram was created or updated by querying the Information Schema COLUMN_STATISTICS table, like this:

SELECT HISTOGRAM FROM INFORMATION_SCHEMA.COLUMN_STATISTICS
  WHERE TABLE_NAME='tbl_name' 
  AND COLUMN_NAME='col_name';

The column value returned should be the same json_data used in the previous ANALYZE TABLE statement.

This can be of use in cases where values deemed important are missed by the histogram sampling process. When this happens, you may want to modify the histogram or set your own histogram based on the complete data set. In addition, sampling a large user data set and building a histogram from it are resource-heavy operations which can impact user queries. With this enhancement, histogram generation can be moved off the (primary) server and performed on a replica instead; the generated histograms can then be assigned to the proper table columns on the source server.

For more information and examples, see Histogram Statistics Analysis.

Server build ID (Linux).  MySQL 8.0.31 adds the read-only build_id system variable for Linux systems, where a 160-bit SHA1 signature is generated at compile time; the value of build_id is that of the generated value converted to a hexadecimal string, providing a unique identifier for the build.

build_id is written to the server log each time MySQL starts.

If you build MySQL from source, you can observe that this value changes each time you recompile the server. See Section 2.8, “Installing MySQL from Source”, for more information.

This variable is not supported on platforms other than Linux.

Default EXPLAIN output format.  MySQL 8.0.32 adds a system variable explain_format which determines the format of the output from an EXPLAIN statement used to obtain a query execution plan in the absence of any FORMAT option. For example, if the value of explain_format is TREE, then the output from any such EXPLAIN uses the tree-like format, just as if the statement had specified FORMAT=TREE.

This behavior is overridden by the value set in a FORMAT option. Suppose that explain_format is set to TREE; even so, EXPLAIN FORMAT=JSON stmt displays the result using the JSON output format.

For more information and examples, see the description of the explain_format system variable, as well as Obtaining Execution Plan Information. There are also implications for the behavior of EXPLAIN ANALYZE; see Obtaining Information with EXPLAIN ANALYZE.

ST_TRANSFORM() Cartesian SRS support.  Prior to MySQL 8.0.30, the ST_TRANSFORM() function did not support Cartesian Spatial Reference Systems. In MySQL 8.0.30 and later, this function provides support for the Popular Visualisation Pseudo Mercator (EPSG 1024) projection method, used for WGS 84 Pseudo-Mercator (SRID 3857). MySQL 8.0.32 and later supports all Cartesian SRSs, except for EPSG 1042, EPSG 1043, EPSG 9816, and EPSG 9826.

mysql client --system-command option.  The --system-command option for the mysql client, available in MySQL 8.0.40 and later, enables or disables the system command.

This option is enabled by default. To disable it, use --system-command=OFF or --skip-system-command, which causes the system command to be rejected with an error.

Wildcard characters in database grants.  The use of the characters % and _ as wildcards in database grants is deprecated as of MySQL 8.0.35. You should expect for the wildcard functionality to removed in a future MySQL release and for these characters always to be treated as literals, as they are already whenever the value of the partial_revokes server system variable is ON.

In addition, the treatment of % by the server as a synonym for localhost when checking privileges is now also deprecated as of MySQL 8.0.35, and thus subject to removal in a future version of MySQL.

Pluggable FIDO authentication is deprecated in MySQL 8.0.35 and later.

The --character-set-client-handshake option, originally intended for use with upgrades from very old versions of MySQL, is now deprecated in MySQL 8.0.35 and later MySQL 8.0 releases, where a warning is issued whenever it is used. You should expect this option to be removed in a future version of MySQL; applications depending on this option should begin migration away from it as soon as possible.

The old and new server system variables and related server options are deprecated in MySQL 8.0, beginning with MySQL 8.0.35. A warning is now issued whenever either of these variables is set or read. Because these variables are destined for removal in a future version of MySQL, applications which depend on them should begin migration away from them as soon as possible.

Legacy audit log filtering mode is deprecated as of MySQL 8.0.34. New deprecation warnings are emitted for legacy audit log filtering system variables. These deprecated variables are either read-only or dynamic.

(Read-only) audit_log_policy now writes a warning message to the MySQL server error log during server startup when the value is not ALL (default value).

(Dynamic) audit_log_include_accounts, audit_log_exclude_accounts, audit_log_statement_policy, and audit_log_connection_policy. Dynamic variables print a warning message based on usage:

In MySQL 8.0.34 and later, the mysql_native_password authentication plugin is deprecated and it now produces a deprecation warning in the server error log if an account attempts to authenticate using mysql_native_password as an authentication method.

The ssl_fips_mode server system variable, --ssl-fips-mode client option, and the MYSQL_OPT_SSL_FIPS_MODE option are deprecated and subject to removal in a future version of MySQL.

The keyring_file and keyring_encrypted_file plugins are deprecated as of MySQL 8.0.34. These keyring plugins are superseded by the component_keyring_file and component_keyring_encrypted_file components. For a concise comparison of keyring components and plugins, see Section 8.4.4.1, “Keyring Components Versus Keyring Plugins”.

As of MySQL 8.0.31, the keyring_oci plugin is deprecated and subject to removal in a future release of MySQL. Instead, consider using the component_keyring_oci component for storing keyring data (see Section 8.4.4.11, “Using the Oracle Cloud Infrastructure Vault Keyring Component”).

The utf8mb3 character set is deprecated. Please use utf8mb4 instead.

The following character sets are deprecated:

In MySQL 8.0.28 and later, any of these character sets or their collations produces a deprecation warning when used in either of the following ways:

You should use utf8mb4 instead any of the character sets listed previously.

User-defined collations are deprecated. Beginning with MySQL 8.0.33, either of the following causes a warning to be written to the log:

You should expect support for user-defined collations to be removed in a future version of MySQL.

Because caching_sha2_password is the default authentication plugin in MySQL 8.0 and provides a superset of the capabilities of the sha256_password authentication plugin, sha256_password is deprecated; expect it to be removed in a future version of MySQL. MySQL accounts that authenticate using sha256_password should be migrated to use caching_sha2_password instead.

The validate_password plugin has been reimplemented to use the component infrastructure. The plugin form of validate_password is still available but is now deprecated; expect it to be removed in a future version of MySQL. MySQL installations that use the plugin should make the transition to using the component instead. See Section 8.4.3.3, “Transitioning to the Password Validation Component”.

The ENGINE clause for the ALTER TABLESPACE and DROP TABLESPACE statements is deprecated.

The PAD_CHAR_TO_FULL_LENGTH SQL mode is deprecated.

AUTO_INCREMENT support is deprecated for columns of type FLOAT and DOUBLE (and any synonyms). Consider removing the AUTO_INCREMENT attribute from such columns, or convert them to an integer type.

The UNSIGNED attribute is deprecated for columns of type FLOAT, DOUBLE, and DECIMAL (and any synonyms). Consider using a simple CHECK constraint instead for such columns.

FLOAT(M,D) and DOUBLE(M,D) syntax to specify the number of digits for columns of type FLOAT and DOUBLE (and any synonyms) is a nonstandard MySQL extension. This syntax is deprecated.

The ZEROFILL attribute is deprecated for numeric data types, as is the display width attribute for integer data types. Consider using an alternative means of producing the effect of these attributes. For example, applications could use the LPAD() function to zero-pad numbers up to the desired width, or they could store the formatted numbers in CHAR columns.

For string data types, the BINARY attribute is a nonstandard MySQL extension that is shorthand for specifying the binary (_bin) collation of the column character set (or of the table default character set if no column character set is specified). In MySQL 8.0, this nonstandard use of BINARY is ambiguous because the utf8mb4 character set has multiple _bin collations, so the BINARY attribute is deprecated; expect support for it to be removed in a future version of MySQL. Applications should be adjusted to use an explicit _bin collation instead.

The use of BINARY to specify a data type or character set remains unchanged.

Previous versions of MySQL supported the nonstandard shorthand expressions ASCII and UNICODE, respectively, for CHARACTER SET latin1 and CHARACTER SET ucs2. ASCII and UNICODE are deprecated (MySQL 8.0.28 and later) and now produce a warning. Use CHARACTER SET instead, in both cases.

The nonstandard C-style &&, ||, and ! operators that are synonyms for the standard SQL AND, OR, and NOT operators, respectively, are deprecated. Applications that use the nonstandard operators should be adjusted to use the standard operators.

The JSON_MERGE() function is deprecated. Use JSON_MERGE_PRESERVE() instead.

The SQL_CALC_FOUND_ROWS query modifier and accompanying FOUND_ROWS() function are deprecated. See the FOUND_ROWS() description for information about an alternative strategy.

Support for TABLESPACE = innodb_file_per_table and TABLESPACE = innodb_temporary clauses with CREATE TEMPORARY TABLE is deprecated as of MySQL 8.0.13.

For SELECT statements, use of an INTO clause after FROM but not at the end of the SELECT is deprecated as of MySQL 8.0.20. It is preferred to place the INTO at the end of the statement.

For UNION statements, these two variants containing INTO are deprecated as of MySQL 8.0.20:

See Section 15.2.13.1, “SELECT ... INTO Statement”, and Section 15.2.18, “UNION Clause”.

FLUSH HOSTS is deprecated as of MySQL 8.0.23. Instead, truncate the Performance Schema host_cache table:

TRUNCATE TABLE performance_schema.host_cache;

The TRUNCATE TABLE operation requires the DROP privilege for the table.

The mysql_upgrade client is deprecated because its capabilities for upgrading the system tables in the mysql system schema and objects in other schemas have been moved into the MySQL server. See Section 3.4, “What the MySQL Upgrade Process Upgrades”.

The --no-dd-upgrade server option is deprecated. It is superseded by the --upgrade option, which provides finer control over data dictionary and server upgrade behavior.

The mysql_upgrade_info file, which is created data directory and used to store the MySQL version number, is deprecated; expect it to be removed in a future version of MySQL.

The relay_log_info_file system variable and --master-info-file option are deprecated. Previously, these were used to specify the name of the relay log info log and source info log when relay_log_info_repository=FILE and master_info_repository=FILE were set, but those settings have been deprecated. The use of files for the relay log info log and source info log has been superseded by crash-safe replica tables, which are the default in MySQL 8.0.

The max_length_for_sort_data system variable is now deprecated due to optimizer changes that make it obsolete and of no effect.

These legacy parameters for compression of connections to the server are deprecated: The --compress client command-line option; the MYSQL_OPT_COMPRESS option for the mysql_options() C API function; the slave_compressed_protocol system variable. For information about parameters to use instead, see Section 6.2.8, “Connection Compression Control”.

Use of the MYSQL_PWD environment variable to specify a MySQL password is deprecated.

Use of VALUES() to access new row values in INSERT ... ON DUPLICATE KEY UPDATE is deprecated as of MySQL 8.0.20. Use aliases for the new row and columns, instead.

Because specifying ON ERROR before ON EMPTY when invoking JSON_TABLE() is counter to the SQL standard, this syntax is now deprecated in MySQL. Beginning with MySQL 8.0.20, the server prints a warning whenever you attempt to do so. When specifying both of these clauses in a single JSON_TABLE() invocation, make sure that ON EMPTY is used first.

Columns with index prefixes have never been supported as part of a table's partitioning key; previously, these were allowed when creating, altering, or upgrading partitioned tables but were excluded by the table's partitioning function, and no warning that this had occurred was issued by the server. This permissive behavior is now deprecated, and subject to removal in a future version of MySQL in which using any such columns in the partitioning key causes the CREATE TABLE or ALTER TABLE statement in they occur to be rejected.

As of MySQL 8.0.21, whenever columns using index prefixes are specified as part of the partitioning key, a warning is generated for each such column. Whenever a CREATE TABLE or ALTER TABLE statement is rejected because all columns in the proposed partitioning key would have index prefixes, the resulting error now provides the exact reason for the rejection. In either instance, this includes cases in which the columns used in the partitioning function are defined implicitly as those in the table's primary key by employing an empty PARTITION BY KEY() clause.

For more information and examples, see Column index prefixes not supported for key partitioning.

The InnoDB memcached plugin is deprecated as of MySQL 8.0.22; expect support for it to be removed in a future version of MySQL.

The temptable_use_mmap variable is deprecated as of MySQL 8.0.26; expect support for it to be removed in a future version of MySQL.

The BINARY operator is deprecated as of MySQL 8.0.27, and you should expect its removal in a future version of MySQL. Use of BINARY now causes a warning. Use CAST(... AS BINARY) instead.

The default_authentication_plugin variable is deprecated as of MySQL 8.0.27; expect support for it to be removed in a future version of MySQL.

The default_authentication_plugin variable is still used in MySQL 8.0.27, but in conjunction with and at a lower precedence than the new authentication_policy system variable, which is introduced in MySQL 8.0.27 with the multifactor authentication feature. For details, see The Default Authentication Plugin.

The --abort-slave-event-count and --disconnect-slave-event-count server options, used by the MySQL test suite and not normally used in production, are deprecated as of MySQL 8.0.29; expect both options to be removed in a future version of MySQL.

The myisam_repair_threads system variable and myisamchk --parallel-recover option are deprecated as of MySQL 8.0.29; expect support for both to be removed in a future release of MySQL.

From MySQL 8.0.29, values other than 1 (the default) for myisam_repair_threads produce a warning.

Previously, MySQL accepted DATE, TIME, DATETIME, and TIMESTAMP literals containing an arbitrary number of (arbitrary) delimiter characters, as well as DATETIME and TIMESTAMP literals with an arbitrary number of whitespace characters before, after, and between the date and time parts. As of MySQL 8.0.29, the server raises a deprecation warning whenever the literal value contains any of the following:

One deprecation warning is issued per temporal value, even if there are multiple issues with it. This warning is not promoted to an error in strict mode, so that performing an INSERT of such a value still succeeds when strict mode is in effect.

You should expect the nonstandard behavior to be removed in a future version of MySQL, and take steps now to insure that your applications do not depend on it.

See String and Numeric Literals in Date and Time Context, for more information and examples.

The replica_parallel_type system variable and its associated server option --replica-parallel-type are deprecated as of MySQL 8.0.29. Beginning with this release, reading or setting this value raises a deprecation warning; expect it to be removed in a future version of MySQL.

Beginning with MySQL 8.0.30, setting the replica_parallel_workers system variable (or the equivalent server option) to 0 is deprecated, and elicits a warning. When you want a replica to use single threading, use replica_parallel_workers=1 instead, which produces the same result, but with no warning.

The --skip-host-cache server option is deprecated beginning with MySQL 8.0.30; expect its removal in a future MySQL release. Use the host_cache_size system variable instead.

The --old-style-user-limits option, intended for backwards compatibility with very old (pre-5.0.3) releases, is deprecated as of MySQL 8.0.30; using it now raises a warning. You should expect this option to be removed in a future release of MySQL.

The innodb_log_files_in_group and innodb_log_file_size variables are deprecated as of MySQL 8.0.30. These variables are superseded by the innodb_redo_log_capacity variable. For more information, see Section 17.6.5, “Redo Log”.

As of MySQL 8.0.32, the use of “FULL” as an unquoted identifier is deprecated, due to the fact that it is a reserved keyword in the SQL standard. This means that a statement such as CREATE TABLE full (c1 INT, c2 INT) now raises a warning (ER_WARN_DEPRECATED_IDENT). To prevent this from happening, change the name or, as shown here, encase it in backticks (`):

CREATE TABLE `full` (c1 INT, c2 INT);

For more information, see Section 11.3, “Keywords and Reserved Words”.

Beginning with MySQL 8.0.32, the use of the dollar sign ($) as the leading character of an unquoted identifier is deprecated and produces a warning. Such usage is subject to removal in a future release of MySQL. This includes identifiers used as names of databases, tables, views, columns, or stored programs, as well as aliases for any of these. The dollar sign may still be used as the first character of a quoted identifier. See Section 11.2, “Schema Object Names”, for more information.

The binlog_format server system variable is deprecated as of MySQL 8.0.34, and is subject to being removed in a future release. Changing the binary logging format, is also deprecated, with the expectation that the removal of binlog_format will leave row-based binary logging, already the default in MySQL 8.0, as the only binary logging format used or supported by MySQL. For this reason, new MySQL installations should use only row-based binary logging; existing replication setups using binlog_format=STATEMENT or binlog_format=MIXED logging format should be migrated to the row-based format.

The system variables log_bin_trust_function_creators and log_statements_unsafe_for_binlog, are used exclusively for statement-based logging and replication. For this reason, they are now also deprecated, and subject to removal in a future version of MySQL.

Setting or selecting the value of binlog_format, log_bin_trust_function_creators, or log_statements_unsafe_for_binlog raises a warning in MySQL 8.0.34 and later.

The mysqlpump client utility program is deprecated beginning with MySQL 8.0.34, and produces a deprecation warning when invoked. This program is subject to removal in a future version of MySQL. Since MySQL provides other means of performing database dumps and backups with the same or additional functionality, including mysqldump and MySQL Shell, this program is now considered redundant.

The associated lz4_decompress and zlib_decompress utilities are also deprecated as of MySQL 8.0.34.

The use of a version number without a whitespace character following (or end of comment) is deprecated as of MySQL 8.0.34, and raises a warning. This statement raises a warning in MySQL 8.0.34 or later, as shown here:

mysql> CREATE TABLE t1(a INT, KEY (a)) /*!50110KEY_BLOCK_SIZE=1024*/ ENGINE=MYISAM;
Query OK, 0 rows affected, 1 warning (0.01 sec)

mysql> SHOW WARNINGS\G
*************************** 1. row ***************************
  Level: Warning
   Code: 4164
Message: Immediately starting the version comment after the version number is
deprecated and may change behavior in a future release. Please insert a
white-space character after the version number.  
1 row in set (0.00 sec)

To avoid such warnings, insert one or more whitespace characters after the version number, like this:

mysql> CREATE TABLE t2(a INT, KEY (a)) /*!50110 KEY_BLOCK_SIZE=1024*/ ENGINE=MYISAM;
Query OK, 0 rows affected (0.00 sec)

See also Section 11.7, “Comments”.

As of MySQL 8.0.34, the sync_relay_log_info system variable is deprecated, along with its equivalent server startup option --sync-relay-log-info. You should expect support for this variable, and for storing replication applier metadata in a file, to be removed in a future version of MySQL. You are advised to update any of your MySQL applications which may depend on it before this occurs.

The binlog_transaction_dependency_tracking server system variable is deprecated as of MySQL 8.0.35, and subject to removal in a future version of MySQL. Referencing this variable or the equivalent mysqld startup option --binlog-transaction-dependency-tracking now triggers a warning. There are no plans to replace this variable or its functionality, which is expected later to be made internal to the server.

The innodb_locks_unsafe_for_binlog system variable was removed. The READ COMMITTED isolation level provides similar functionality.

The information_schema_stats variable, introduced in MySQL 8.0.0, was removed and replaced by information_schema_stats_expiry in MySQL 8.0.3.

information_schema_stats_expiry defines an expiration setting for cached INFORMATION_SCHEMA table statistics. For more information, see Section 10.2.3, “Optimizing INFORMATION_SCHEMA Queries”.

Code related to obsolete InnoDB system tables was removed in MySQL 8.0.3. INFORMATION_SCHEMA views based on InnoDB system tables were replaced by internal system views on data dictionary tables. Affected InnoDB INFORMATION_SCHEMA views were renamed:

After upgrading to MySQL 8.0.3 or later, update any scripts that reference previous InnoDB INFORMATION_SCHEMA view names.

The following features related to account management are removed:

The query cache was removed. Removal includes these items:

These deprecated query cache items remain deprecated, but have no effect; expect them to be removed in a future MySQL release:

The have_query_cache system variable remains deprecated, and always has a value of NO; expect it to be removed in a future MySQL release.

The data dictionary provides information about database objects, so the server no longer checks directory names in the data directory to find databases. Consequently, the --ignore-db-dir option and ignore_db_dirs system variables are extraneous and are removed.

The DDL log, also known as the metadata log, has been removed. Beginning with MySQL 8.0.3, this functionality is handled by the data dictionary innodb_ddl_log table. See Viewing DDL Logs.

The tx_isolation and tx_read_only system variables have been removed. Use transaction_isolation and transaction_read_only instead.

The sync_frm system variable has been removed because .frm files have become obsolete.

The secure_auth system variable and --secure-auth client option have been removed. The MYSQL_SECURE_AUTH option for the mysql_options() C API function was removed.

The multi_range_count system variable is removed.

The log_warnings system variable and --log-warnings server option have been removed. Use the log_error_verbosity system variable instead.

The global scope for the sql_log_bin system variable was removed. sql_log_bin has session scope only, and applications that rely on accessing @@GLOBAL.sql_log_bin should be adjusted.

The metadata_locks_cache_size and metadata_locks_hash_instances system variables are removed.

The unused date_format, datetime_format, time_format, and max_tmp_tables system variables are removed.

These deprecated compatibility SQL modes are removed: DB2, MAXDB, MSSQL, MYSQL323, MYSQL40, ORACLE, POSTGRESQL, NO_FIELD_OPTIONS, NO_KEY_OPTIONS, NO_TABLE_OPTIONS. They can no longer be assigned to the sql_mode system variable or used as permitted values for the mysqldump --compatible option.

Removal of MAXDB means that the TIMESTAMP data type for CREATE TABLE or ALTER TABLE is treated as TIMESTAMP, and is no longer treated as DATETIME.

The deprecated ASC or DESC qualifiers for GROUP BY clauses are removed. Queries that previously relied on GROUP BY sorting may produce results that differ from previous MySQL versions. To produce a given sort order, provide an ORDER BY clause.

The EXTENDED and PARTITIONS keywords for the EXPLAIN statement have been removed. These keywords are unnecessary because their effect is always enabled.

These encryption-related items are removed:

In place of the removed encryption functions: For ENCRYPT(), consider using SHA2() instead for one-way hashing. For the others, consider using AES_ENCRYPT() and AES_DECRYPT() instead.

In MySQL 5.7, several spatial functions available under multiple names were deprecated to move in the direction of making the spatial function namespace more consistent, the goal being that each spatial function name begin with ST_ if it performs an exact operation, or with MBR if it performs an operation based on minimum bounding rectangles. In MySQL 8.0, the deprecated functions are removed to leave only the corresponding ST_ and MBR functions:

The functions described in Section 14.16.4, “Functions That Create Geometry Values from WKB Values” previously accepted either WKB strings or geometry arguments. Geometry arguments are no longer permitted and produce an error. See that section for guidelines for migrating queries away from using geometry arguments.

The parser no longer treats \N as a synonym for NULL in SQL statements. Use NULL instead.

This change does not affect text file import or export operations performed with LOAD DATA or SELECT ... INTO OUTFILE, for which NULL continues to be represented by \N. See Section 15.2.9, “LOAD DATA Statement”.

PROCEDURE ANALYSE() syntax is removed.

The client-side --ssl and --ssl-verify-server-cert options have been removed. Use --ssl-mode=REQUIRED instead of --ssl=1 or --enable-ssl. Use --ssl-mode=DISABLED instead of --ssl=0, --skip-ssl, or --disable-ssl. Use --ssl-mode=VERIFY_IDENTITY instead of --ssl-verify-server-cert options. (The server-side --ssl option is still available, but is deprecated as of MySQL 8.0.26 and subject to removal in a future MySQL version.)

For the C API, MYSQL_OPT_SSL_ENFORCE and MYSQL_OPT_SSL_VERIFY_SERVER_CERT options for mysql_options() correspond to the client-side --ssl and --ssl-verify-server-cert options and are removed. Use MYSQL_OPT_SSL_MODE with an option value of SSL_MODE_REQUIRED or SSL_MODE_VERIFY_IDENTITY instead.

The --temp-pool server option was removed.

The ignore_builtin_innodb system variable is removed.

The server no longer performs conversion of pre-MySQL 5.1 database names containing special characters to 5.1 format with the addition of a #mysql50# prefix. Because these conversions are no longer performed, the --fix-db-names and --fix-table-names options for mysqlcheck, the UPGRADE DATA DIRECTORY NAME clause for the ALTER DATABASE statement, and the Com_alter_db_upgrade status variable are removed.

Upgrades are supported only from one major version to another (for example, 5.0 to 5.1, or 5.1 to 5.5), so there should be little remaining need for conversion of older 5.0 database names to current versions of MySQL. As a workaround, upgrade a MySQL 5.0 installation to MySQL 5.1 before upgrading to a more recent release.

The mysql_install_db program has been removed from MySQL distributions. Data directory initialization should be performed by invoking mysqld with the --initialize or --initialize-insecure option instead. In addition, the --bootstrap option for mysqld that was used by mysql_install_db was removed, and the INSTALL_SCRIPTDIR CMake option that controlled the installation location for mysql_install_db was removed.

The generic partitioning handler was removed from the MySQL server. In order to support partitioning of a given table, the storage engine used for the table must now provide its own (“native”) partitioning handler. The --partition and --skip-partition options are removed from the MySQL Server, and partitioning-related entries are no longer shown in the output of SHOW PLUGINS or in the Information Schema PLUGINS table.

Two MySQL storage engines currently provide native partitioning support: InnoDB and NDB. Of these, only InnoDB is supported in MySQL 8.0. Any attempt to create partitioned tables in MySQL 8.0 using any other storage engine fails.

Ramifications for upgrades.  The direct upgrade of a partitioned table using a storage engine other than InnoDB (such as MyISAM) from MySQL 5.7 (or earlier) to MySQL 8.0 is not supported. There are two options for handling such a table:

At least one of the two operations just listed must be performed for each partitioned non-InnoDB table prior to upgrading the server to MySQL 8.0. Otherwise, such a table cannot be used following the upgrade.

Due to the fact that table creation statements that would result in a partitioned table using a storage engine without partitioning support now fail with an error (ER_CHECK_NOT_IMPLEMENTED), you must make sure that any statements in a dump file (such as that written by mysqldump) from an older version of MySQL that you wish to import into a MySQL 8.0 server that create partitioned tables do not also specify a storage engine such as MyISAM that has no native partitioning handler. You can do this by performing either of the following:

For more information, see Section 26.6.2, “Partitioning Limitations Relating to Storage Engines”.

System and status variable information is no longer maintained in the INFORMATION_SCHEMA. These tables are removed: GLOBAL_VARIABLES, SESSION_VARIABLES, GLOBAL_STATUS, SESSION_STATUS. Use the corresponding Performance Schema tables instead. See Section 29.12.14, “Performance Schema System Variable Tables”, and Section 29.12.15, “Performance Schema Status Variable Tables”. In addition, the show_compatibility_56 system variable was removed. It was used in the transition period during which system and status variable information in INFORMATION_SCHEMA tables was moved to Performance Schema tables, and is no longer needed. These status variables are removed: Slave_heartbeat_period, Slave_last_heartbeat, Slave_received_heartbeats, Slave_retried_transactions, Slave_running. The information they provided is available in Performance Schema tables; see Migrating to Performance Schema System and Status Variable Tables.

The Performance Schema setup_timers table was removed, as was the TICK row in the performance_timers table.

The libmysqld embedded server library is removed, along with:

The mysql_plugin utility was removed. Alternatives include loading plugins at server startup using the --plugin-load or --plugin-load-add option, or at runtime using the INSTALL PLUGIN statement.

The resolveip utility is removed. nslookup, host, or dig can be used instead.

The resolve_stack_dump utility is removed. Stack traces from official MySQL builds are always symbolized, so there is no need to use resolve_stack_dump.

The following server error codes are not used and have been removed. Applications that test specifically for any of these errors should be updated.

ER_BINLOG_READ_EVENT_CHECKSUM_FAILURE
ER_BINLOG_ROW_RBR_TO_SBR
ER_BINLOG_ROW_WRONG_TABLE_DEF
ER_CANT_ACTIVATE_LOG
ER_CANT_CHANGE_GTID_NEXT_IN_TRANSACTION
ER_CANT_CREATE_FEDERATED_TABLE
ER_CANT_CREATE_SROUTINE
ER_CANT_DELETE_FILE
ER_CANT_GET_WD
ER_CANT_SET_GTID_PURGED_WHEN_GTID_MODE_IS_OFF
ER_CANT_SET_WD
ER_CANT_WRITE_LOCK_LOG_TABLE
ER_CREATE_DB_WITH_READ_LOCK
ER_CYCLIC_REFERENCE
ER_DB_DROP_DELETE
ER_DELAYED_NOT_SUPPORTED
ER_DIFF_GROUPS_PROC
ER_DISK_FULL
ER_DROP_DB_WITH_READ_LOCK
ER_DROP_USER
ER_DUMP_NOT_IMPLEMENTED
ER_ERROR_DURING_CHECKPOINT
ER_ERROR_ON_CLOSE
ER_EVENTS_DB_ERROR
ER_EVENT_CANNOT_DELETE
ER_EVENT_CANT_ALTER
ER_EVENT_COMPILE_ERROR
ER_EVENT_DATA_TOO_LONG
ER_EVENT_DROP_FAILED
ER_EVENT_MODIFY_QUEUE_ERROR
ER_EVENT_NEITHER_M_EXPR_NOR_M_AT
ER_EVENT_OPEN_TABLE_FAILED
ER_EVENT_STORE_FAILED
ER_EXEC_STMT_WITH_OPEN_CURSOR
ER_FAILED_ROUTINE_BREAK_BINLOG
ER_FLUSH_MASTER_BINLOG_CLOSED
ER_FORM_NOT_FOUND
ER_FOUND_GTID_EVENT_WHEN_GTID_MODE_IS_OFF__UNUSED
ER_FRM_UNKNOWN_TYPE
ER_GOT_SIGNAL
ER_GRANT_PLUGIN_USER_EXISTS
ER_GTID_MODE_REQUIRES_BINLOG
ER_GTID_NEXT_IS_NOT_IN_GTID_NEXT_LIST
ER_HASHCHK
ER_INDEX_REBUILD
ER_INNODB_NO_FT_USES_PARSER
ER_LIST_OF_FIELDS_ONLY_IN_HASH_ERROR
ER_LOAD_DATA_INVALID_COLUMN_UNUSED
ER_LOGGING_PROHIBIT_CHANGING_OF
ER_MALFORMED_DEFINER
ER_MASTER_KEY_ROTATION_ERROR_BY_SE
ER_NDB_CANT_SWITCH_BINLOG_FORMAT
ER_NEVER_USED
ER_NISAMCHK
ER_NO_CONST_EXPR_IN_RANGE_OR_LIST_ERROR
ER_NO_FILE_MAPPING
ER_NO_GROUP_FOR_PROC
ER_NO_RAID_COMPILED
ER_NO_SUCH_KEY_VALUE
ER_NO_SUCH_PARTITION__UNUSED
ER_OBSOLETE_CANNOT_LOAD_FROM_TABLE
ER_OBSOLETE_COL_COUNT_DOESNT_MATCH_CORRUPTED
ER_ORDER_WITH_PROC
ER_PARTITION_SUBPARTITION_ERROR
ER_PARTITION_SUBPART_MIX_ERROR
ER_PART_STATE_ERROR
ER_PASSWD_LENGTH
ER_QUERY_ON_MASTER
ER_RBR_NOT_AVAILABLE
ER_SKIPPING_LOGGED_TRANSACTION
ER_SLAVE_CHANNEL_DELETE
ER_SLAVE_MULTIPLE_CHANNELS_HOST_PORT
ER_SLAVE_MUST_STOP
ER_SLAVE_WAS_NOT_RUNNING
ER_SLAVE_WAS_RUNNING
ER_SP_GOTO_IN_HNDLR
ER_SP_PROC_TABLE_CORRUPT
ER_SQL_MODE_NO_EFFECT
ER_SR_INVALID_CREATION_CTX
ER_TABLE_NEEDS_UPG_PART
ER_TOO_MUCH_AUTO_TIMESTAMP_COLS
ER_UNEXPECTED_EOF
ER_UNION_TABLES_IN_DIFFERENT_DIR
ER_UNSUPPORTED_BY_REPLICATION_THREAD
ER_UNUSED1
ER_UNUSED2
ER_UNUSED3
ER_UNUSED4
ER_UNUSED5
ER_UNUSED6
ER_VIEW_SELECT_DERIVED_UNUSED
ER_WRONG_MAGIC
ER_WSAS_FAILED

The deprecated INFORMATION_SCHEMA INNODB_LOCKS and INNODB_LOCK_WAITS tables are removed. Use the Performance Schema data_locks and data_lock_waits tables instead.

InnoDB no longer supports compressed temporary tables. When innodb_strict_mode is enabled (the default), CREATE TEMPORARY TABLE returns an error if ROW_FORMAT=COMPRESSED or KEY_BLOCK_SIZE is specified. If innodb_strict_mode is disabled, warnings are issued and the temporary table is created using a non-compressed row format.

InnoDB no longer creates .isl files (InnoDB Symbolic Link files) when creating tablespace data files outside of the MySQL data directory. The innodb_directories option now supports locating tablespace files created outside of the data directory.

With this change, moving a remote tablespace while the server is offline by manually modifying an .isl file is no longer supported. Moving remote tablespace files is now supported by the innodb_directories option. See Section 17.6.3.6, “Moving Tablespace Files While the Server is Offline”.

The following InnoDB file format variables were removed:

File format variables were necessary for creating tables compatible with earlier versions of InnoDB in MySQL 5.1. Now that MySQL 5.1 has reached the end of its product lifecycle, these options are no longer required.

The FILE_FORMAT column was removed from the INNODB_TABLES and INNODB_TABLESPACES Information Schema tables.

The innodb_support_xa system variable, which enables support for two-phase commit in XA transactions, was removed. InnoDB support for two-phase commit in XA transactions is always enabled.

Support for DTrace was removed.

The JSON_APPEND() function was removed. Use JSON_ARRAY_APPEND() instead.

Support for placing table partitions in shared InnoDB tablespaces was removed in MySQL 8.0.13. Shared tablespaces include the InnoDB system tablespace and general tablespaces. For information about identifying partitions in shared tablespaces and moving them to file-per-table tablespaces, see Section 3.6, “Preparing Your Installation for Upgrade”.

Support for setting user variables in statements other than SET was deprecated in MySQL 8.0.13. This functionality is subject to removal in MySQL 8.4.

The --ndb perror option was removed. Use the ndb_perror utility instead.

The innodb_undo_logs variable was removed. The innodb_rollback_segments variables performs the same function and should be used instead.

The Innodb_available_undo_logs status variable was removed. The number of available rollback segments per tablespace may be retrieved using SHOW VARIABLES LIKE 'innodb_rollback_segments';

As of MySQL 8.0.14, the previously deprecated innodb_undo_tablespaces variable is no longer configurable. For more information, see Section 17.6.3.4, “Undo Tablespaces”.

Support for the ALTER TABLE ... UPGRADE PARTITIONING statement has been removed.

As of MySQL 8.0.16, support for the internal_tmp_disk_storage_engine system variable has been removed; internal temporary tables on disk now always use the InnoDB storage engine. See Storage Engine for On-Disk Internal Temporary Tables,for more information.

The DISABLE_SHARED CMake option was unused and has been removed.

The myisam_repair_threads system variable is removed as of MySQL 8.0.30.