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MySQL 5.7 Reference Manual  /  General Information  /  What Is New in MySQL 5.7

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, “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, “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, “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:


      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:

    • The Fusion-io Non-Volatile Memory (NVM) file system on Linux provides atomic write capability, which makes the InnoDB doublewrite buffer redundant. The InnoDB doublewrite buffer is automatically disabled for system tablespace files (ibdata files) located on Fusion-io devices that support atomic writes.

    • InnoDB supports the Transportable Tablespace 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, “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, “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, “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:

    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”.


    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, “GET DIAGNOSTICS Statement”, and Section, “The MySQL Diagnostics Area”.

  • Optimizer.  These optimizer enhancements were added:

  • 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, “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, “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, “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, “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:

    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.

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, “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, “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 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.