1.3 What Is New in MySQL 5.7

This section summarizes what has been added to, deprecated in, and removed from MySQL 5.7. A companion section lists MySQL server options and variables that have been added, deprecated, or removed in MySQL 5.7; see Section 1.4, “Server and Status Variables and Options Added, Deprecated, or Removed in MySQL 5.7”.

Features Added in MySQL 5.7

The following features have been added to MySQL 5.7:

Security improvements. These security enhancements were added:
- In MySQL 8.0, caching_sha2_password is the default authentication plugin. To enable MySQL 5.7 clients to connect to 8.0 servers using accounts that authenticate using caching_sha2_password, the MySQL 5.7 client library and client programs support the caching_sha2_password client-side authentication plugin as of MySQL 5.7.23. This improves compatibility of MySQL 5.7 with MySQL 8.0 and higher servers. See Section 6.4.1.4, “Caching SHA-2 Pluggable Authentication”.
- The server now requires account rows in the mysql.user system table to have a nonempty plugin column value and disables accounts with an empty value. For server upgrade instructions, see Section 2.10.3, “Changes in MySQL 5.7”. DBAs are advised to also convert accounts that use the mysql_old_password authentication plugin to use mysql_native_password instead, because support for mysql_old_password has been removed. For account upgrade instructions, see Section 6.4.1.3, “Migrating Away from Pre-4.1 Password Hashing and the mysql_old_password Plugin”.
- MySQL now enables database administrators to establish a policy for automatic password expiration: Any user who connects to the server using an account for which the password is past its permitted lifetime must change the password. For more information, see Section 6.2.11, “Password Management”.
- Administrators can lock and unlock accounts for better control over who can log in. For more information, see Section 6.2.15, “Account Locking”.
- To make it easier to support secure connections, MySQL servers compiled using OpenSSL can automatically generate missing SSL and RSA certificate and key files at startup. See Section 6.3.3.1, “Creating SSL and RSA Certificates and Keys using MySQL”.
  
  All servers, if not configured for SSL explicitly, attempt to enable SSL automatically at startup if they find the requisite SSL files in the data directory. See Section 6.3.1, “Configuring MySQL to Use Encrypted Connections”.
  
  In addition, MySQL distributions include a mysql_ssl_rsa_setup utility that can be invoked manually to create SSL and RSA key and certificate files. For more information, see Section 4.4.5, “mysql_ssl_rsa_setup — Create SSL/RSA Files”.
- MySQL deployments installed using mysqld --initialize are secure by default. The following changes have been implemented as the default deployment characteristics:
  - The installation process creates only a single root account, 'root'@'localhost', automatically generates a random password for this account, and marks the password expired. The MySQL administrator must connect as root using the random password and assign a new password. (The server writes the random password to the error log.)
  - Installation creates no anonymous-user accounts.
  - Installation creates no test database.
  For more information, see Section 2.9.1, “Initializing the Data Directory”.
- MySQL Enterprise Edition now provides data masking and de-identification capabilities. Data masking hides sensitive information by replacing real values with substitutes. MySQL Enterprise Data Masking and De-Identification functions enable masking existing data using several methods such as obfuscation (removing identifying characteristics), generation of formatted random data, and data replacement or substitution. For more information, see Section 6.5, “MySQL Enterprise Data Masking and De-Identification”.
- MySQL now sets the access control granted to clients on the named pipe to the minimum necessary for successful communication on Windows. Newer MySQL client software can open named pipe connections without any additional configuration. If older client software cannot be upgraded immediately, the new named_pipe_full_access_group system variable can be used to give a Windows group the necessary permissions to open a named pipe connection. Membership in the full-access group should be restricted and temporary.
SQL mode changes. Strict SQL mode for transactional storage engines (STRICT_TRANS_TABLES) is now enabled by default.

Implementation for the ONLY_FULL_GROUP_BY SQL mode has been made more sophisticated, to no longer reject deterministic queries that previously were rejected. In consequence, this mode is now enabled by default, to prohibit only nondeterministic queries containing expressions not guaranteed to be uniquely determined within a group.

The ERROR_FOR_DIVISION_BY_ZERO, NO_ZERO_DATE, and NO_ZERO_IN_DATE SQL modes are now deprecated but enabled by default. The long term plan is to have them included in strict SQL mode and to remove them as explicit modes in a future MySQL release. See SQL Mode Changes in MySQL 5.7.

The changes to the default SQL mode result in a default sql_mode system variable value with these modes enabled: ONLY_FULL_GROUP_BY, STRICT_TRANS_TABLES, NO_ZERO_IN_DATE, NO_ZERO_DATE, ERROR_FOR_DIVISION_BY_ZERO, NO_AUTO_CREATE_USER, and NO_ENGINE_SUBSTITUTION.
Online ALTER TABLE. ALTER TABLE now supports a RENAME INDEX clause that renames an index. The change is made in place without a table-copy operation. It works for all storage engines. See Section 13.1.8, “ALTER TABLE Statement”.
ngram and MeCab full-text parser plugins. MySQL provides a built-in full-text ngram parser plugin that supports Chinese, Japanese, and Korean (CJK), and an installable MeCab full-text parser plugin for Japanese.

For more information, see Section 12.9.8, “ngram Full-Text Parser”, and Section 12.9.9, “MeCab Full-Text Parser Plugin”.
InnoDB enhancements. These InnoDB enhancements were added:
- VARCHAR column size can be increased using an in-place ALTER TABLE, as in this example:
```
ALTER TABLE t1 ALGORITHM=INPLACE, CHANGE COLUMN c1 c1 VARCHAR(255);
```
  This is true as long as the number of length bytes required by a VARCHAR column remains the same. For VARCHAR columns of 0 to 255 bytes in size, one length byte is required to encode the value. For VARCHAR columns of 256 bytes in size or more, two length bytes are required. As a result, in-place ALTER TABLE only supports increasing VARCHAR column size from 0 to 255 bytes, or from 256 bytes to a greater size. In-place ALTER TABLE does not support increasing the size of a VARCHAR column from less than 256 bytes to a size equal to or greater than 256 bytes. In this case, the number of required length bytes changes from 1 to 2, which is only supported by a table copy (ALGORITHM=COPY).
  
  Decreasing VARCHAR size using in-place ALTER TABLE is not supported. Decreasing VARCHAR size requires a table copy (ALGORITHM=COPY).
  
  For more information, see Section 14.13.1, “Online DDL Operations”.
- DDL performance for InnoDB temporary tables is improved through optimization of CREATE TABLE, DROP TABLE, TRUNCATE TABLE, and ALTER TABLE statements.
- InnoDB temporary table metadata is no longer stored to InnoDB system tables. Instead, a new table, INNODB_TEMP_TABLE_INFO, provides users with a snapshot of active temporary tables. The table contains metadata and reports on all user and system-created temporary tables that are active within a given InnoDB instance. The table is created when the first SELECT statement is run against it.
- InnoDB now supports MySQL-supported spatial data types. Prior to this release, InnoDB would store spatial data as binary BLOB data. BLOB remains the underlying data type but spatial data types are now mapped to a new InnoDB internal data type, DATA_GEOMETRY.
- There is now a separate tablespace for all non-compressed InnoDB temporary tables. The new tablespace is always recreated on server startup and is located in DATADIR by default. A newly added configuration file option, innodb_temp_data_file_path, allows for a user-defined temporary data file path.
- innochecksum functionality is enhanced with several new options and extended capabilities. See Section 4.6.1, “innochecksum — Offline InnoDB File Checksum Utility”.
- A new type of non-redo undo log for both normal and compressed temporary tables and related objects now resides in the temporary tablespace. For more information, see Section 14.6.7, “Undo Logs”.
- InnoDB buffer pool dump and load operations are enhanced. A new system variable, innodb_buffer_pool_dump_pct, allows you to specify the percentage of most recently used pages in each buffer pool to read out and dump. When there is other I/O activity being performed by InnoDB background tasks, InnoDB attempts to limit the number of buffer pool load operations per second using the innodb_io_capacity setting.
- Support is added to InnoDB for full-text parser plugins. For information about full-text parser plugins, see Full-Text Parser Plugins and Writing Full-Text Parser Plugins.
- InnoDB supports multiple page cleaner threads for flushing dirty pages from buffer pool instances. A new system variable, innodb_page_cleaners, is used to specify the number of page cleaner threads. The default value of 1 maintains the previous configuration in which there is a single page cleaner thread. This enhancement builds on work completed in MySQL 5.6, which introduced a single page cleaner thread to offload buffer pool flushing work from the InnoDB master thread.
- Online DDL support is extended to the following operations for regular and partitioned InnoDB tables:
  - OPTIMIZE TABLE
  - ALTER TABLE ... FORCE
  - ALTER TABLE ... ENGINE=INNODB (when run on an InnoDB table)
    
    Online DDL support reduces table rebuild time and permits concurrent DML. See Section 14.13, “InnoDB and Online DDL”.
- The Fusion-io Non-Volatile Memory (NVM) file system on Linux provides write capability, which makes the InnoDB redundant. The InnoDB doublewrite buffer is automatically disabled for system tablespace files () located on Fusion-io devices that support atomic writes.
- InnoDB supports the feature for partitioned InnoDB tables and individual InnoDB table partitions. This enhancement eases backup procedures for partitioned tables and enables copying of partitioned tables and individual table partitions between MySQL instances. For more information, see Section 14.6.1.3, “Importing InnoDB Tables”.
- The innodb_buffer_pool_size parameter is dynamic, allowing you to resize the buffer pool without restarting the server. The resizing operation, which involves moving pages to a new location in memory, is performed in chunks. Chunk size is configurable using the new innodb_buffer_pool_chunk_size configuration option. You can monitor resizing progress using the new Innodb_buffer_pool_resize_status status variable. For more information, see Configuring InnoDB Buffer Pool Size Online.
- Multithreaded page cleaner support (innodb_page_cleaners) is extended to shutdown and recovery phases.
- InnoDB supports indexing of spatial data types using SPATIAL indexes, including use of ALTER TABLE ... ALGORITHM=INPLACE for online operations (ADD SPATIAL INDEX).
- InnoDB performs a bulk load when creating or rebuilding indexes. This method of index creation is known as a “sorted index build”. This enhancement, which improves the efficiency of index creation, also applies to full-text indexes. A new global configuration option, innodb_fill_factor, defines the percentage of space on each page that is filled with data during a sorted index build, with the remaining space reserved for future index growth. For more information, see Section 14.6.2.3, “Sorted Index Builds”.
- A new log record type (MLOG_FILE_NAME) is used to identify tablespaces that have been modified since the last checkpoint. This enhancement simplifies tablespace discovery during crash recovery and eliminates scans on the file system prior to redo log application. For more information about the benefits of this enhancement, see Tablespace Discovery During Crash Recovery.
  
  This enhancement changes the redo log format, requiring that MySQL be shut down cleanly before upgrading to or downgrading from MySQL 5.7.5.
- You can truncate undo logs that reside in undo tablespaces. This feature is enabled using the innodb_undo_log_truncate configuration option. For more information, see Truncating Undo Tablespaces.
- InnoDB supports native partitioning. Previously, InnoDB relied on the ha_partition handler, which creates a handler object for each partition. With native partitioning, a partitioned InnoDB table uses a single partition-aware handler object. This enhancement reduces the amount of memory required for partitioned InnoDB tables.
  
  As of MySQL 5.7.9, mysql_upgrade looks for and attempts to upgrade partitioned InnoDB tables that were created using the ha_partition handler. Also in MySQL 5.7.9 and later, you can upgrade such tables by name in the mysql client using ALTER TABLE ... UPGRADE PARTITIONING.
- InnoDB supports the creation of general tablespaces using CREATE TABLESPACE syntax.
```
CREATE TABLESPACE `tablespace_name`
  ADD DATAFILE 'file_name.ibd'
  [FILE_BLOCK_SIZE = n]
```
  General tablespaces can be created outside of the MySQL data directory, are capable of holding multiple tables, and support tables of all row formats.
  
  Tables are added to a general tablespace using CREATE TABLE tbl_name ... TABLESPACE [=] tablespace_name or ALTER TABLE tbl_name TABLESPACE [=] tablespace_name syntax.
  
  For more information, see Section 14.6.3.3, “General Tablespaces”.
- DYNAMIC replaces COMPACT as the implicit default row format for InnoDB tables. A new configuration option, innodb_default_row_format, specifies the default InnoDB row format. For more information, see Defining the Row Format of a Table.
- As of MySQL 5.7.11, InnoDB supports data-at-rest encryption for file-per-table tablespaces. Encryption is enabled by specifying the ENCRYPTION option when creating or altering an InnoDB table. This feature relies on a keyring plugin for encryption key management. For more information, see Section 6.4.4, “The MySQL Keyring”, and Section 14.14, “InnoDB Data-at-Rest Encryption”.
- As of MySQL 5.7.24, the zlib library version bundled with MySQL was raised from version 1.2.3 to version 1.2.11. MySQL implements compression with the help of the zlib library.
  
  If you use InnoDB compressed tables, see Section 2.10.3, “Changes in MySQL 5.7” for related upgrade implications.
JSON support. Beginning with MySQL 5.7.8, MySQL supports a native JSON type. JSON values are not stored as strings, instead using an internal binary format that permits quick read access to document elements. JSON documents stored in JSON columns are automatically validated whenever they are inserted or updated, with an invalid document producing an error. JSON documents are normalized on creation, and can be compared using most comparison operators such as =, <, <=, >, >=, <>, !=, and <=>; for information about supported operators as well as precedence and other rules that MySQL follows when comparing JSON values, see Comparison and Ordering of JSON Values.

MySQL 5.7.8 also introduces a number of functions for working with JSON values. These functions include those listed here:
- Functions that create JSON values: JSON_ARRAY(), JSON_MERGE(), and JSON_OBJECT(). See Section 12.17.2, “Functions That Create JSON Values”.
- Functions that search JSON values: JSON_CONTAINS(), JSON_CONTAINS_PATH(), JSON_EXTRACT(), JSON_KEYS(), and JSON_SEARCH(). See Section 12.17.3, “Functions That Search JSON Values”.
- Functions that modify JSON values: JSON_APPEND(), JSON_ARRAY_APPEND(), JSON_ARRAY_INSERT(), JSON_INSERT(), JSON_QUOTE(), JSON_REMOVE(), JSON_REPLACE(), JSON_SET(), and JSON_UNQUOTE(). See Section 12.17.4, “Functions That Modify JSON Values”.
- Functions that provide information about JSON values: JSON_DEPTH(), JSON_LENGTH(), JSON_TYPE(), and JSON_VALID(). See Section 12.17.5, “Functions That Return JSON Value Attributes”.
In MySQL 5.7.9 and later, you can use column->path as shorthand for JSON_EXTRACT(column, path). This works as an alias for a column wherever a column identifier can occur in an SQL statement, including WHERE, ORDER BY, and GROUP BY clauses. This includes SELECT, UPDATE, DELETE, CREATE TABLE, and other SQL statements. The left hand side must be a JSON column identifier (and not an alias). The right hand side is a quoted JSON path expression which is evaluated against the JSON document returned as the column value.

MySQL 5.7.22 adds the following JSON functions:
- Two JSON aggregation functions JSON_ARRAYAGG() and JSON_OBJECTAGG(). JSON_ARRAYAGG() takes a column or expression as its argument, and aggregates the result as a single JSON array. The expression can evaluate to any MySQL data type; this does not have to be a JSON value. JSON_OBJECTAGG() takes two columns or expressions which it interprets as a key and a value; it returns the result as a single JSON object. For more information and examples, see Section 12.19, “Aggregate Functions”.
- The JSON utility function JSON_PRETTY(), which outputs an existing JSON value in an easy-to-read format; each JSON object member or array value is printed on a separate line, and a child object or array is intended 2 spaces with respect to its parent.
  
  This function also works with a string that can be parsed as a JSON value.
  
  See also Section 12.17.6, “JSON Utility Functions”.
- The JSON utility function JSON_STORAGE_SIZE(), which returns the storage space in bytes used for the binary representation of a JSON document prior to any partial update (see previous item).
  
  This function also accepts a valid string representation of a JSON document. For such a value, JSON_STORAGE_SIZE() returns the space used by its binary representation following its conversion to a JSON document. For a variable containing the string representation of a JSON document, JSON_STORAGE_FREE() returns zero. Either function produces an error if its (non-null) argument cannot be parsed as a valid JSON document, and NULL if the argument is NULL.
  
  For more information and examples, see Section 12.17.6, “JSON Utility Functions”.
- A JSON merge function intended to conform to RFC 7396. JSON_MERGE_PATCH(), when used on 2 JSON objects, merges them into a single JSON object that has as members a union of the following sets:
  - Each member of the first object for which there is no member with the same key in the second object.
  - Each member of the second object for which there is no member having the same key in the first object, and whose value is not the JSON null literal.
  - Each member having a key that exists in both objects, and whose value in the second object is not the JSON null literal.
  As part of this work, the JSON_MERGE() function has been renamed JSON_MERGE_PRESERVE(). JSON_MERGE() continues to be recognized as an alias for JSON_MERGE_PRESERVE() in MySQL 5.7, but is now deprecated and is subject to removal in a future version of MySQL.
  
  For more information and examples, see Section 12.17.4, “Functions That Modify JSON Values”.
See Section 12.17.3, “Functions That Search JSON Values”, for more information about -> and JSON_EXTRACT(). For information about JSON path support in MySQL 5.7, see Searching and Modifying JSON Values. See also Indexing a Generated Column to Provide a JSON Column Index.
System and status variables. System and status variable information is now available in Performance Schema tables, in preference to use of INFORMATION_SCHEMA tables to obtain these variable. This also affects the operation of the SHOW VARIABLES and SHOW STATUS statements. The value of the show_compatibility_56 system variable affects the output produced from and privileges required for system and status variable statements and tables. For details, see the description of that variable in Section 5.1.7, “Server System Variables”.

Note

The default for show_compatibility_56 is OFF. Applications that require 5.6 behavior should set this variable to ON until such time as they have been migrated to the new behavior for system variables and status variables. See Section 25.20, “Migrating to Performance Schema System and Status Variable Tables”
sys schema. MySQL distributions now include the sys schema, which is a set of objects that help DBAs and developers interpret data collected by the Performance Schema. sys schema objects can be used for typical tuning and diagnosis use cases. For more information, see Chapter 26, MySQL sys Schema.
Condition handling. MySQL now supports stacked diagnostics areas. When the diagnostics area stack is pushed, the first (current) diagnostics area becomes the second (stacked) diagnostics area and a new current diagnostics area is created as a copy of it. Within a condition handler, executed statements modify the new current diagnostics area, but GET STACKED DIAGNOSTICS can be used to inspect the stacked diagnostics area to obtain information about the condition that caused the handler to activate, independent of current conditions within the handler itself. (Previously, there was a single diagnostics area. To inspect handler-activating conditions within a handler, it was necessary to check this diagnostics area before executing any statements that could change it.) See Section 13.6.7.3, “GET DIAGNOSTICS Statement”, and Section 13.6.7.7, “The MySQL Diagnostics Area”.
Optimizer. These optimizer enhancements were added:
- EXPLAIN can be used to obtain the execution plan for an explainable statement executing in a named connection:
```
EXPLAIN [options] FOR CONNECTION connection_id;
```
  For more information, see Section 8.8.4, “Obtaining Execution Plan Information for a Named Connection”.
- It is possible to provide hints to the optimizer within individual SQL statements, which enables finer control over statement execution plans than can be achieved using the optimizer_switch system variable. Hints are also permitted in statements used with EXPLAIN, enabling you to see how hints affect execution plans. For more information, see Section 8.9.3, “Optimizer Hints”.
- prefer_ordering_index flag. By default, MySQL attempts to use an ordered index for any ORDER BY or GROUP BY query that has a LIMIT clause, whenever the optimizer determines that this would result in faster execution. Because it is possible in some cases that choosing a different optimization for such queries actually performs better, it is possible as of MySQL 5.7.33 to disable this optimization by setting the prefer_ordering_index flag to off.
  
  The default value for this flag is on.
  
  For more information and examples, see Section 8.9.2, “Switchable Optimizations”, and Section 8.2.1.17, “LIMIT Query Optimization”.
Triggers. Previously, a table could have at most one trigger for each combination of trigger event (INSERT, UPDATE, DELETE) and action time (BEFORE, AFTER). This limitation has been lifted and multiple triggers are permitted. For more information, see Section 23.3, “Using Triggers”.
Logging. These logging enhancements were added:
- Previously, on Unix and Unix-like systems, MySQL support for sending the server error log to syslog was implemented by having mysqld_safe capture server error output and pass it to syslog. The server now includes native syslog support, which has been extended to include Windows. For more information about sending server error output to syslog, see Section 5.4.2, “The Error Log”.
- The mysql client now has a --syslog option that causes interactive statements to be sent to the system syslog facility. Logging is suppressed for statements that match the default “ignore” pattern list ("*IDENTIFIED*:*PASSWORD*"), as well as statements that match any patterns specified using the --histignore option. See Section 4.5.1.3, “mysql Client Logging”.
Generated Columns. MySQL now supports the specification of generated columns in CREATE TABLE and ALTER TABLE statements. Values of a generated column are computed from an expression specified at column creation time. Generated columns can be virtual (computed “on the fly” when rows are read) or stored (computed when rows are inserted or updated). For more information, see Section 13.1.18.7, “CREATE TABLE and Generated Columns”.
mysql client. Previously, Control+C in mysql interrupted the current statement if there was one, or exited mysql if not. Now Control+C interrupts the current statement if there was one, or cancels any partial input line otherwise, but does not exit.
Database name rewriting with mysqlbinlog. Renaming of databases by mysqlbinlog when reading from binary logs written using the row-based format is now supported using the --rewrite-db option added in MySQL 5.7.1.

This option uses the format --rewrite-db='dboldname->dbnewname'. You can implement multiple rewrite rules, by specifying the option multiple times.
HANDLER with partitioned tables. The HANDLER statement may now be used with user-partitioned tables. Such tables may use any of the available partitioning types (see Section 22.2, “Partitioning Types”).
Index condition pushdown support for partitioned tables. Queries on partitioned tables using the InnoDB or MyISAM storage engine may employ the index condition pushdown optimization that was introduced in MySQL 5.6. See Section 8.2.1.5, “Index Condition Pushdown Optimization”, for more information.
WITHOUT VALIDATION support for ALTER TABLE ... EXCHANGE PARTITION. As of MySQL 5.7.5, ALTER TABLE ... EXCHANGE PARTITION syntax includes an optional {WITH|WITHOUT} VALIDATION clause. When WITHOUT VALIDATION is specified, ALTER TABLE ... EXCHANGE PARTITION does not perform row-by-row validation when exchanging a populated table with the partition, permitting database administrators to assume responsibility for ensuring that rows are within the boundaries of the partition definition. WITH VALIDATION is the default behavior and need not be specified explicitly. For more information, see Section 22.3.3, “Exchanging Partitions and Subpartitions with Tables”.
Source dump thread improvements. The source dump thread was refactored to reduce lock contention and improve source throughput. Previous to MySQL 5.7.2, the dump thread took a lock on the binary log whenever reading an event; in MySQL 5.7.2 and later, this lock is held only while reading the position at the end of the last successfully written event. This means both that multiple dump threads are now able to read concurrently from the binary log file, and that dump threads are now able to read while clients are writing to the binary log.
Character set support. MySQL 5.7.4 includes a gb18030 character set that supports the China National Standard GB18030 character set. For more information about MySQL character set support, see Chapter 10, Character Sets, Collations, Unicode.
Changing the replication source without STOP SLAVE. In MySQL 5.7.4 and later, the strict requirement to execute STOP SLAVE prior to issuing any CHANGE MASTER TO statement is removed. Instead of depending on whether the replica is stopped, the behavior of CHANGE MASTER TO now depends on the states of the replica SQL thread and replica I/O threads; which of these threads is stopped or running now determines the options that can or cannot be used with a CHANGE MASTER TO statement at a given point in time. The rules for making this determination are listed here:
- If the SQL thread is stopped, you can execute CHANGE MASTER TO using any combination of RELAY_LOG_FILE, RELAY_LOG_POS, and MASTER_DELAY options, even if the replica I/O thread is running. No other options may be used with this statement when the I/O thread is running.
- If the I/O thread is stopped, you can execute CHANGE MASTER TO using any of the options for this statement (in any allowed combination) except RELAY_LOG_FILE, RELAY_LOG_POS, or MASTER_DELAY, even when the SQL thread is running. These three options may not be used when the I/O thread is running.
- Both the SQL thread and the I/O thread must be stopped before issuing CHANGE MASTER TO ... MASTER_AUTO_POSITION = 1.
You can check the current state of the replica SQL and I/O threads using SHOW SLAVE STATUS.

If you are using statement-based replication and temporary tables, it is possible for a CHANGE MASTER TO statement following a STOP SLAVE statement to leave behind temporary tables on the replica. As part of this set of improvements, a warning is now issued whenever CHANGE MASTER TO is issued following STOP SLAVE when statement-based replication is in use and Slave_open_temp_tables remains greater than 0.

For more information, see Section 13.4.2.1, “CHANGE MASTER TO Statement”, and Section 16.3.7, “Switching Sources During Failover”.
Test suite. The MySQL test suite now uses InnoDB as the default storage engine.
Multi-source replication is now possible. MySQL Multi-Source Replication adds the ability to replicate from multiple sources to a replica. MySQL Multi-Source Replication topologies can be used to back up multiple servers to a single server, to merge table shards, and consolidate data from multiple servers to a single server. See Section 16.1.5, “MySQL Multi-Source Replication”.

As part of MySQL Multi-Source Replication, replication channels have been added. Replication channels enable a replica to open multiple connections to replicate from, with each channel being a connection to a source. See Section 16.2.2, “Replication Channels”.
Group Replication Performance Schema tables. MySQL 5.7 adds a number of new tables to the Performance Schema to provide information about replication groups and channels. These include the following tables:
All of these tables were added in MySQL 5.7.2, except for replication_group_members and replication_group_member_stats, which were added in MySQL 5.7.6. For more information, see Section 25.12.11, “Performance Schema Replication Tables”.
Group Replication SQL. The following statements were added in MySQL 5.7.6 for controlling Group Replication:
- START GROUP_REPLICATION
- STOP GROUP_REPLICATION
For more information, see Section 13.4.3, “SQL Statements for Controlling Group Replication”.

Features Deprecated in MySQL 5.7

The following features are deprecated in MySQL 5.7 and may be removed in a future series. Where alternatives are shown, applications should be updated to use them.

For applications that use features deprecated in MySQL 5.7 that have been removed in a higher MySQL series, statements may fail when replicated from a MySQL 5.7 source to a higher-series replica, or may have different effects on source and replica. To avoid such problems, applications that use features deprecated in 5.7 should be revised to avoid them and use alternatives when possible.

The ERROR_FOR_DIVISION_BY_ZERO, NO_ZERO_DATE, and NO_ZERO_IN_DATE SQL modes are now deprecated but enabled by default. The long term plan is to have them included in strict SQL mode and to remove them as explicit modes in a future MySQL release.

The deprecated ERROR_FOR_DIVISION_BY_ZERO, NO_ZERO_DATE, and NO_ZERO_IN_DATE SQL modes are still recognized so that statements that name them do not produce an error, but are expected to be removed in a future version of MySQL. To make advance preparation for versions of MySQL in which these mode names do not exist, applications should be modified not to refer to them. See SQL Mode Changes in MySQL 5.7.
These SQL modes are now deprecated; expect them to be removed in a future version of MySQL: DB2, MAXDB, MSSQL, MYSQL323, MYSQL40, ORACLE, POSTGRESQL, NO_FIELD_OPTIONS, NO_KEY_OPTIONS, NO_TABLE_OPTIONS. These deprecations have two implications:
- Assigning a deprecated mode to the sql_mode system variable produces a warning.
- With the MAXDB SQL mode enabled, using CREATE TABLE or ALTER TABLE to add a TIMESTAMP column to a table produces a warning.
Changes to account-management statements make the following features obsolete. They are now deprecated:
- Using GRANT to create users. Instead, use CREATE USER. Following this practice makes the NO_AUTO_CREATE_USER SQL mode immaterial for GRANT statements, so it too is deprecated.
- Using GRANT to modify account properties other than privilege assignments. This includes authentication, SSL, and resource-limit properties. Instead, establish such properties at account-creation time with CREATE USER or modify them afterward with ALTER USER.
- IDENTIFIED BY PASSWORD 'auth_string' syntax for CREATE USER and GRANT. Instead, use IDENTIFIED WITH auth_plugin AS 'auth_string' for CREATE USER and ALTER USER, where the 'auth_string' value is in a format compatible with the named plugin.
- The PASSWORD() function is deprecated and should be avoided in any context. Thus, SET PASSWORD ... = PASSWORD('auth_string') syntax is also deprecated. SET PASSWORD ... = 'auth_string' syntax is not deprecated; nevertheless, ALTER USER is now the preferred statement for assigning passwords.
- The old_passwords system variable. Account authentication plugins can no longer be left unspecified in the mysql.user system table, so any statement that assigns a password from a cleartext string can unambiguously determine the hashing method to use on the string before storing it in the mysql.user table. This renders old_passwords superflous.
The query cache is deprecated. Deprecation includes these items:
- The FLUSH QUERY CACHE and RESET QUERY CACHE statements.
- The SQL_CACHE and SQL_NO_CACHE SELECT modifiers.
- These system variables: have_query_cache, ndb_cache_check_time, query_cache_limit, query_cache_min_res_unit, query_cache_size, query_cache_type, query_cache_wlock_invalidate.
- These status variables: Qcache_free_blocks, Qcache_free_memory, Qcache_hits, Qcache_inserts, Qcache_lowmem_prunes, Qcache_not_cached, Qcache_queries_in_cache, Qcache_total_blocks.
Previously, the --transaction-isolation and --transaction-read-only server startup options corresponded to the tx_isolation and tx_read_only system variables. For better name correspondence between startup option and system variable names, transaction_isolation and transaction_read_only have been created as aliases for tx_isolation and tx_read_only. The tx_isolation and tx_read_only variables are now deprecated;expect them to be removed in MySQL 8.0. Applications should be adjusted to use transaction_isolation and transaction_read_only instead.
The --skip-innodb option and its synonyms (--innodb=OFF, --disable-innodb, and so forth) are deprecated. These options have no effect as of MySQL 5.7. because InnoDB cannot be disabled.
The client-side --ssl and --ssl-verify-server-cert options are deprecated. 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 not deprecated.)

For the C API, MYSQL_OPT_SSL_ENFORCE and MYSQL_OPT_SSL_VERIFY_SERVER_CERT options for correspond to the client-side --ssl and --ssl-verify-server-cert options and are deprecated. Use MYSQL_OPT_SSL_MODE with an option value of SSL_MODE_REQUIRED or SSL_MODE_VERIFY_IDENTITY instead.
The log_warnings system variable and --log-warnings server option are deprecated. Use the log_error_verbosity system variable instead.
The --temp-pool server option is deprecated.
The binlog_max_flush_queue_time system variable does nothing in MySQL 5.7, and is deprecated as of MySQL 5.7.9.
The innodb_support_xa system variable, which enables InnoDB support for two-phase commit in XA transactions, is deprecated as of MySQL 5.7.10. InnoDB support for two-phase commit in XA transactions is always enabled as of MySQL 5.7.10.
The metadata_locks_cache_size and metadata_locks_hash_instances system variables are deprecated. These do nothing as of MySQL 5.7.4.
The sync_frm system variable is deprecated.
The global character_set_database and collation_database system variables are deprecated; expect them to be removed in a future version of MySQL.

Assigning a value to the session character_set_database and collation_database system variables is deprecated and assignments produce a warning. The session variables are expected to become read only in a future version of MySQL, and assignments to them to produce an error, while remaining possible to read the session variables to determine the database character set and collation for the default database.
The global scope for the sql_log_bin system variable has been deprecated, and this variable can now be set with session scope only. The statement SET GLOBAL SQL_LOG_BIN now produces an error. It remains possible to read the global value of sql_log_bin, but doing so produces a warning. You should act now to remove from your applications any dependencies on reading this value; the global scope sql_log_bin is removed in MySQL 8.0.
With the introduction of the data dictionary in MySQL 8.0, the --ignore-db-dir option and ignore_db_dirs system variable became superfluous and were removed in that version. Consequently, they are deprecated in MySQL 5.7.
GROUP BY implicitly sorts by default (that is, in the absence of ASC or DESC designators), but relying on implicit GROUP BY sorting in MySQL 5.7 is deprecated. To achieve a specific sort order of grouped results, it is preferable to use To produce a given sort order, use explicit ASC or DESC designators for GROUP BY columns or provide an ORDER BY clause. GROUP BY sorting is a MySQL extension that may change in a future release; for example, to make it possible for the optimizer to order groupings in whatever manner it deems most efficient and to avoid the sorting overhead.
The EXTENDED and PARTITIONS keywords for the EXPLAIN statement are deprecated. These keywords are still recognized but are now unnecessary because their effect is always enabled.
The ENCRYPT(), ENCODE(), DECODE(), DES_ENCRYPT(), and DES_DECRYPT() encryption functions are deprecated. For ENCRYPT(), consider using SHA2() instead for one-way hashing. For the others, consider using AES_ENCRYPT() and AES_DECRYPT() instead. The --des-key-file option, the have_crypt system variable, the DES_KEY_FILE option for the FLUSH statement, and the HAVE_CRYPT CMake option also are deprecated.
The MBREqual() spatial function is deprecated. Use MBREquals() instead.
The functions described in Section 12.16.4, “Functions That Create Geometry Values from WKB Values” previously accepted either WKB strings or geometry arguments. Use of geometry arguments is deprecated. See that section for guidelines for migrating queries away from using geometry arguments.
The INFORMATION_SCHEMA PROFILING table is deprecated. Use the Performance Schema instead; see Chapter 25, MySQL Performance Schema.
The INFORMATION_SCHEMA INNODB_LOCKS and INNODB_LOCK_WAITS tables are deprecated, to be removed in MySQL 8.0, which provides replacement Performance Schema tables.
The Performance Schema setup_timers table is deprecated and is removed in MySQL 8.0, as is the TICK row in the performance_timers table.
The sys schema sys.version view is deprecated; expect it be removed in a future version of MySQL. Affected applications should be adjusted to use an alternative instead. For example, use the VERSION() function to retrieve the MySQL server version.
Treatment of \N as a synonym for NULL in SQL statements is deprecated and is removed in MySQL 8.0; 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 13.2.6, “LOAD DATA Statement”.
PROCEDURE ANALYSE() syntax is deprecated.
Comment stripping by the mysql client and the options to control it (--skip-comments, --comments) are deprecated.
mysqld_safe support for syslog output is deprecated. Use the native server syslog support used instead. See Section 5.4.2, “The Error Log”.
Conversion of pre-MySQL 5.1 database names containing special characters to 5.1 format with the addition of a #mysql50# prefix is deprecated. Because of this, the --fix-db-names and --fix-table-names options for mysqlcheck and the UPGRADE DATA DIRECTORY NAME clause for the ALTER DATABASE statement are also deprecated.

Upgrades are supported only from one release series 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.
mysql_install_db functionality has been integrated into the MySQL server, mysqld. To use this capability to initialize a MySQL installation, if you previously invoked mysql_install_db manually, invoke mysqld with the --initialize or --initialize-insecure option, depending on whether you want the server to generate a random password for the initial 'root'@'localhost' account.

mysql_install_db is now deprecated, as is the special --bootstrap option that mysql_install_db passes to mysqld.
The mysql_plugin utility is deprecated. 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 deprecated. nslookup, host, or dig can be used instead.
The resolve_stack_dump utility is deprecated. Stack traces from official MySQL builds are always symbolized, so there is no need to use resolve_stack_dump.
The , , , and C API functions are deprecated. The same is true of the corresponding COM_PROCESS_KILL, COM_FIELD_LIST, COM_PROCESS_INFO, and COM_REFRESH client/server protocol commands. Instead, use to execute a KILL, SHOW COLUMNS, SHOW PROCESSLIST, or FLUSH statement, respectively.
The mysql_shutdown() C API function is deprecated. Instead, use to execute a SHUTDOWN statement.
The libmysqld embedded server library is deprecated as of MySQL 5.7.19. These are also deprecated:
- The mysql_config --libmysqld-libs, --embedded-libs, and --embedded options
- The CMake WITH_EMBEDDED_SERVER, WITH_EMBEDDED_SHARED_LIBRARY, and INSTALL_SECURE_FILE_PRIV_EMBEDDEDDIR options
- The (undocumented) mysql --server-arg option
- The mysqltest --embedded-server, --server-arg, and --server-file options
- The mysqltest_embedded and mysql_client_test_embedded test programs
Because libmysqld uses an API comparable to that of libmysqlclient, the migration path away from libmysqld is straightforward:
1. Bring up a standalone MySQL server (mysqld).
2. Modify application code to remove API calls that are specific to libmysqld.
3. Modify application code to connect to the standalone MySQL server.
4. Modify build scripts to use libmysqlclient rather than libmysqld. For example, if you use mysql_config, invoke it with the --libs option rather than --libmysqld-libs.
The replace utility is deprecated.
Support for DTrace is deprecated.
The JSON_MERGE() function is deprecated as of MySQL 5.7.22. Use JSON_MERGE_PRESERVE() instead.
Support for placing table partitions in shared InnoDB tablespaces is deprecated as of MySQL 5.7.24. 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 .
Support for TABLESPACE = innodb_file_per_table and TABLESPACE = innodb_temporary clauses with CREATE TEMPORARY TABLE is deprecated as of MySQL 5.7.24.
The --ndb perror option is deprecated. Use the ndb_perror utility instead.
The myisam_repair_threads system variable myisam_repair_threads are deprecated as of MySQL 5.7.38; expect support for both to be removed in a future release of MySQL.

From MySQL 5.7.38, values other than 1 (the default) for myisam_repair_threads produce a warning.

Features Removed in MySQL 5.7

The following items are obsolete and have been removed in MySQL 5.7. Where alternatives are shown, applications should be updated to use them.

For MySQL 5.6 applications that use features removed in MySQL 5.7, statements may fail when replicated from a MySQL 5.6 source to a MySQL 5.7 replica, or may have different effects on source and replica. To avoid such problems, applications that use features removed in MySQL 5.7 should be revised to avoid them and use alternatives when possible.

Support for passwords that use the older pre-4.1 password hashing format is removed, which involves the following changes. Applications that use any feature no longer supported must be modified.
- The mysql_old_password authentication plugin is removed. Accounts that use this plugin are disabled at startup and the server writes an “unknown plugin” message to the error log. For instructions on upgrading accounts that use this plugin, see Section 6.4.1.3, “Migrating Away from Pre-4.1 Password Hashing and the mysql_old_password Plugin”.
- The --secure-auth option to the server and client programs is the default, but is now a no-op. It is deprecated; expect it to be removed in a future MySQL release.
- The --skip-secure-auth option to the server and client programs is no longer supported and using it produces an error.
- The secure_auth system variable permits only a value of 1; a value of 0 is no longer permitted.
- For the old_passwords system variable, a value of 1 (produce pre-4.1 hashes) is no longer permitted.
- The OLD_PASSWORD() function is removed.
In MySQL 5.6.6, the 2-digit YEAR(2) data type was deprecated. Support for YEAR(2) is now removed. Once you upgrade to MySQL 5.7.5 or higher, any remaining 2-digit YEAR(2) columns must be converted to 4-digit YEAR columns to become usable again. For conversion strategies, see Section 11.2.5, “2-Digit YEAR(2) Limitations and Migrating to 4-Digit YEAR”. For example, run mysql_upgrade after upgrading.
The innodb_mirrored_log_groups system variable. The only supported value was 1, so it had no purpose.
The storage_engine system variable. Use default_storage_engine instead.
The thread_concurrency system variable.
The timed_mutexes system variable, which had no effect.
The IGNORE clause for ALTER TABLE.
INSERT DELAYED is no longer supported. The server recognizes but ignores the DELAYED keyword, handles the insert as a nondelayed insert, and generates an ER_WARN_LEGACY_SYNTAX_CONVERTED warning. (“INSERT DELAYED is no longer supported. The statement was converted to INSERT.”) Similarly, REPLACE DELAYED is handled as a nondelayed replace. You should expect the DELAYED keyword to be removed in a future release.

In addition, several DELAYED-related options or features were removed:
- The --delayed-insert option for mysqldump.
- The COUNT_WRITE_DELAYED, SUM_TIMER_WRITE_DELAYED, MIN_TIMER_WRITE_DELAYED, AVG_TIMER_WRITE_DELAYED, and MAX_TIMER_WRITE_DELAYED columns of the Performance Schema table_lock_waits_summary_by_table table.
- mysqlbinlog no longer writes comments mentioning INSERT DELAYED.
Database symlinking on Windows using .sym files has been removed because it is redundant with native symlink support available using mklink. Any .sym file symbolic links are now ignored and should be replaced with symlinks created using mklink. See Section 8.12.3.3, “Using Symbolic Links for Databases on Windows”.
The unused --basedir, --datadir, and --tmpdir options for mysql_upgrade were removed.
Previously, program options could be specified in full or as any unambiguous prefix. For example, the --compress option could be given to mysqldump as --compr, but not as --comp because the latter is ambiguous. Option prefixes are no longer supported; only full options are accepted. This is because prefixes can cause problems when new options are implemented for programs and a prefix that is currently unambiguous might become ambiguous in the future. Some implications of this change:
- The --key-buffer option must now be specified as --key-buffer-size.
- The --skip-grant option must now be specified as --skip-grant-tables.
SHOW ENGINE INNODB MUTEX output is removed. Comparable information can be generated by creating views on Performance Schema tables.
The InnoDB Tablespace Monitor and InnoDB Table Monitor are removed. For the Table Monitor, equivalent information can be obtained from InnoDB INFORMATION_SCHEMA tables.
The specially named tables used to enable and disable the standard InnoDB Monitor and InnoDB Lock Monitor (innodb_monitor and innodb_lock_monitor) are removed and replaced by two dynamic system variables: innodb_status_output and innodb_status_output_locks. For additional information, see Section 14.18, “InnoDB Monitors”.
The innodb_use_sys_malloc and innodb_additional_mem_pool_size system variables, deprecated in MySQL 5.6.3, were removed.
The msql2mysql, mysql_convert_table_format, mysql_find_rows, mysql_fix_extensions, mysql_setpermission, mysql_waitpid, mysql_zap, mysqlaccess, and mysqlbug utilities.
The mysqlhotcopy utility. Alternatives include mysqldump and MySQL Enterprise Backup.
The binary-configure.sh script.
The INNODB_PAGE_ATOMIC_REF_COUNT CMake option is removed.
The innodb_create_intrinsic option is removed.
The innodb_optimize_point_storage option and related internal data types (DATA_POINT and DATA_VAR_POINT) are removed.
The innodb_log_checksum_algorithm option is removed.
The myisam_repair_threads system variable as of MySQL 5.7.39.