derived tables make possible certain SQL operations that cannot be done with nonlateral derived tables or that require less-efficient workarounds. See Section 13.2.11.9, “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 12.8.2, “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. 

• 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.  Error logging was rewritten to use the MySQL component architecture. Traditional error logging is implemented using built-in components, and logging using the system log is implemented as a loadable component. In addition, a loadable JSON log writer is available. To control which log components to enable, use the log_error_services  system variable. For more information, see Section 5.4.2, “The Error Log” . 

• 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: 

•MySQL Replication now supports binary logging of partial updates to JSON documents using a compact binary format, saving space in the log over logging complete JSON documents. Such compact logging is done automatically when statement-based logging is in use, and can be enabled by setting the new binlog_row_value_options  system variable to PARTIAL_JSON . For more information, see Partial Updates of JSON Values, as well as the description of binlog_row_value_options . 

• 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 5.1.12.1, “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 

