1.4. What Is New in MySQL 5.7

This section summarizes what has been added to and removed from MySQL 5.7.

Added Features

The following features have been added to MySQL 5.7:

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 13.1.6, "ALTER TABLE Syntax".
InnoDB enhancements. These InnoDB enhancements were added:
- VARCHAR size may 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 values of 0 to 255, one length byte is required to encode the value. For VARCHAR values of 256 bytes or more, two length bytes are required. As a result, in-place ALTER TABLE only supports increasing VARCHAR size from 0 to 255 bytes or increasing VARCHAR size from a value equal to or greater than 256 bytes.
  
  In-place ALTER TABLE does not support increasing VARCHAR size from less than 256 bytes to a value equal to or greater than 256 bytes. In this case, the number of required length bytes would change from 1 to 2, which is only supported by a table copy (ALGORITHM=COPY). For example, attempting to change VARCHAR column size from 255 to 256 using in-place ALTER TABLE would return an error:
```
ALTER TABLE t1 ALGORITHM=INPLACE, CHANGE COLUMN c1 c1 VARCHAR(256);ERROR 0A000: ALGORITHM=INPLACE is not supported. Reason: Cannot changecolumn type INPLACE. Try ALGORITHM=COPY.
```
  Decreasing VARCHAR size using in-place ALTER TABLE is not supported. Decreasing VARCHAR size requires a table copy (ALGORITHM=COPY).
- 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.
- In MySQL 5.7.2, innochecksum functionality has been 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 will now reside in the temporary tablespace. For more information, see Section 14.2.3.12, "InnoDB Temporary Table Undo Logs".
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 Syntax", and Section 13.6.7.7, "The MySQL Diagnostics Area".
Logging. 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 Logging".
Test suite. The MySQL test suite now uses InnoDB as the default storage engine.
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 17.2, "Partitioning Types").

Removed Features

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

The innodb_mirrored_log_groups system variable. The only supported value was 1, so it had no purpose.
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. The DELAYED keyword will 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 for .sym files has been removed because it is redundant with native symlink support available using mklink. Any .sym file symbolic links will be ignored and should be replaced with symlinks created using mklink. See Section 8.11.3.1.3, "Using Symbolic Links for Databases on Windows".
The unused --basedir and --datadir 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.