Key Improvements in MySQL 8.0.13 and 8.0.14

Since the official release of MySQL 8.0.11, four subsequent versions (8.0.12‑8.0.15) have been published; this article focuses on the noteworthy improvements in MySQL 8.0.13 and 8.0.14.

MySQL 8.0.13

Key Improvements and Features

1. Faster execution of SELECT COUNT(*) FROM tbl_name when there is no WHERE clause or other GROUP BY expressions.

2. Support for Skip Scan access , a form of index‑skip scanning. Example:

CREATE TABLE t1 (
  f1 INT NOT NULL,
  f2 INT NOT NULL,
  PRIMARY KEY (f1, f2)
);
INSERT INTO t1 VALUES (1,1), (1,2), (1,3), (1,4), (1,5);
INSERT INTO t1 VALUES (2,1), (2,2), (2,3), (2,4), (2,5);
INSERT INTO t1 SELECT f1, f2+5 FROM t1;
INSERT INTO t1 SELECT f1, f2+10 FROM t1;
INSERT INTO t1 SELECT f1, f2+20 FROM t1;
INSERT INTO t1 SELECT f1, f2+40 FROM t1;
ANALYZE TABLE t1;
EXPLAIN SELECT f1, f2 FROM t1 WHERE f2 > 40;

The optimizer can use Skip Scan only when the following conditions are met:

All selected columns are covered by a composite index.

The leftmost prefix of the index is not used in the WHERE clause, but the remaining columns are.

The query involves a single table.

The query does not contain GROUP BY or DISTINCT .

The WHERE clause includes a range condition on a non‑leftmost index column.

Although this feature challenges the traditional “left‑most prefix” rule, it should be considered a supplement rather than a replacement for proper index design.

Deprecated Parameters and Features

Partition tables will no longer be stored in shared tablespaces.

The TABLESPACE = innodb_file_per_table and TABLESPACE = innodb_temporary attributes for CREATE TEMPORARY TABLE are deprecated.

The utf8mb3 character set is deprecated; use utf8mb4 instead.

Removal of metadata_locks_cache_size and metadata_locks_hash_instances .

Deprecation of sql_mode=PAD_CHAR_TO_FULL_LENGTH .

MySQL 8.0.14

Key Improvements and Features

1. Enhanced operability: an admin address allows administrators to connect even when the main connection limit is reached.

2. Support for dual passwords, enabling smoother password rotation. Example:

ALTER USER 'appuser1'@'host1.example.com' IDENTIFIED BY 'password_b' RETAIN CURRENT PASSWORD;

3. Ability to create and drop additional undo tablespaces at runtime. Example:

CREATE UNDO TABLESPACE tablespace_name ADD DATAFILE 'file_name.ibu'; DROP UNDO TABLESPACE tablespace_name;

4. Parallel read of clustered indexes to speed up CHECK TABLE , controlled by innodb_parallel_read_threads (default 4). This does not apply to secondary indexes.

5. When innodb_dedicated_server is enabled, the number and size of redo log files adjust automatically based on the buffer pool size.

6. In‑place ALTER TABLE for character set changes, provided:

The column type is CHAR , VARCHAR , TEXT , or ENUM .

The conversion is from utf8mb3 to utf8mb4 or any charset to BINARY .

The column is not indexed.

7. New MRG parameter group_replication_consistency to control consistency reads in Group Replication clusters, with values EVENTUAL , BEFORE_ON_PRIMARY_FAILOVER , BEFORE , AFTER , and BEFORE_AND_AFTER .

Reference Documents

https://dev.mysql.com/doc/relnotes/mysql/8.0/en/news-8-0-13.html

https://dev.mysql.com/doc/relnotes/mysql/8.0/en/news-8-0-14.html

Original content was reposted from Yang Qilong’s public account (yangyidba) and includes additional community links and announcements.