Preview of the upcoming new features in MySQL 8.0.17

Note: I am no longer working for Oracle/MySQL. This post is based on public information.

The MySQL 8.0.17 release is around the corner. Let's take a look at the new features in the upcoming release.

InnoDB redo log archive

InnoDB added new parameter “--innodb-redo-log-archive-dirs” in 8.0.17, according to the doc page. The implementation of both page archive and redo log archive has been in the code for a while, under arch directory. This feature can be used by backup and database clone.

Multi-Valued Indexes

As of MySQL 8.0.17, InnoDB supports multi-valued indexes. A multi-valued index is a secondary index defined on a column that stores an array of values. A “normal” index has one index record for each data record (1:1). A multi-valued index can have multiple index records for a single data record (N:1). Multi-valued indexes are intended for indexing JSON arrays. For example, a multi-valued index defined on the array of zip codes in the following JSON document creates an index record for each zip code, with each index record referencing the same data record.

It has some good examples on the page. Also listed Limitations and Restrictions on Multi-valued Indexes.

The LOCK_ORDER Tool

As of MySQL 8.0.17, to enable detection of lock-acquisition deadlocks and enforcement that runtime execution is free of them, MySQL supports LOCK_ORDER tooling. This enables a lock-order dependency graph to be defined as part of server design, and server runtime checking to ensure that lock acquisition is acyclic and that execution paths comply with the graph.

The LOCK_ORDER tool is intended for debugging the server, not for production use.

Table 29.4 LOCK_ORDER System Variable Summary

Variable Name	Variable Type	Variable Scope
lock_order	Boolean	Global
lock_order_debug_loop	Boolean	Global
lock_order_debug_missing_arc	Boolean	Global
lock_order_debug_missing_key	Boolean	Global
lock_order_debug_missing_unlock	Boolean	Global
lock_order_dependencies	File name	Global
lock_order_extra_dependencies	File name	Global
lock_order_output_directory	Directory name	Global
lock_order_print_txt	Boolean	Global
lock_order_trace_loop	Boolean	Global
lock_order_trace_missing_arc	Boolean	Global
lock_order_trace_missing_key	Boolean	Global
lock_order_trace_missing_unlock	Boolean	Global

Default the tool is disabled in source, according to the source configuration options:

-DWITH_LOCK_ORDER=bool

Whether to enable LOCK_ORDER tooling. By default, this option is disabled and server builds contain no tooling. If tooling is enabled, the LOCK_ORDER tool is available and can be used as described in Section 29.5.3, “The LOCK_ORDER Tool”.

Other Changes

Early plugin loading

From 8.0.17, all early loading plugins must specify the following flag:

#define PLUGIN_OPT_ALLOW_EARLY  4UL   /* allow --early-plugin-load */

This flag was added in MySQL 8.0.17. All plugins compiled using MySQL distributions prior to 8.0.17 do not have this flag set. When loading these into pre-8.0.17 servers this does not matter, but attempts to use --early-plugin-load to load plugin binaries compiled using pre-8.0.17 MySQL distributions into a 8.0.17 or higher server will fail. The plugins must be recompiled against MySQL 8.0.17 or higher.

Additional Target Types for Casts.

The functions CAST() and CONVERT() now support conversions to types DOUBLE, FLOAT, and REAL. 

JSON Schema Validation

MySQL 8.0.17 adds two functions JSON_SCHEMA_VALID() and JSON_SCHEMA_VALIDATION_REPORT() for validating JSON documents again JSON schemas. 

hintable time_zone

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

Encryption of binlog temporary files

From MySQL 8.0.17, when binary log encryption is active on the server, temporary files used to hold the binary log cache are encrypted using AES-CTR (AES Counter mode) for stream encryption. Because the temporary files are volatile and tied to a single process, they are encrypted using single-tier encryption, using a randomly generated file password and initialization vector that exist only in memory and are never stored on disk or in the keyring.

print_identified_with_as_hex

For SHOW CREATE USER, print hash values containing unprintable characters in hex. Added in MySQL 8.0.17.

Upgrade on case sensitive file system

Due to a regression introduced in MySQL 8.0.14, in-place upgrade on a case sensitive file system from MySQL 5.7 or a MySQL 8.0 release prior to MySQL 8.0.14 to MySQL 8.0.16 failed for instances with partitioned tables and lower_case_table_names=1.

Reserved Keyword

ARRAY (R); added in 8.0.17 (reserved)

MEMBER (R); added in 8.0.17 (reserved)

Compress option

--compress is only used in one release (8.0.17).

Option Name	Description	Introduced	Deprecated	Removed
--compress	Compress all information sent between client and server	8.0.17	8.0.18
--compression-algorithms	Permitted compression algorithms for connections to server	8.0.18

This option was added in MySQL 8.0.17. As of MySQL 8.0.18 it is deprecated. It will be removed in a future MySQL version.