DBLE 3.21.06.0 Release Notes Overview

DBLE (also known as "MyCat Plus") is an enterprise‑grade open‑source distributed middleware. This release note introduces version 3.21.06.0, the second release of the year.

Project Introduction

DBLE offers data horizontal partitioning, read/write separation, distributed transaction support, multi‑shard algorithms, global IDs, and IP/SQL whitelist capabilities, with strong MySQL syntax compatibility and low migration cost.

Key Feature Updates

A new global switch allows users to decide whether to convert in‑Subquery to a join.

Further optimization of query plans to avoid unnecessary rewriting when subqueries share the same table and routing.

Support for XA transaction residue checks, exposing potential leftover XIDs during startup and runtime.

Full Release Notes

Features

Dynamic thread‑pool size adjustment.

MariaDB driver option useBatchMultiSend support.

SQL statistics queue utilization monitoring.

XA transaction residue check.

Fixes for shard routing on LEFT JOIN and UNION.

Switch for inSubquery conversion to join.

Upgrade Druid to version 1.2.6.

Cluster data restructuring requiring backup‑delete‑recreate steps.

Major Bug Fixes

Correct behavior of set autocommit .

Prevent OOM when slow‑log is enabled.

Resolve transaction failures in read/write separation.

Address table consistency check issues.

Fix thread leaks caused by complex queries.

Correct results when = appears in GROUP BY.

Update default jumpStringHash settings.

Various NullPointerException fixes.

Incompatibilities with Previous Versions

The default for the inSubquery ‑to‑join switch changed from true to false.

Cluster data restructuring requires backup‑delete‑recreate.

Commands such as file @@... and show @@syslog have been removed.

Default jumpStringHash settings have changed, requiring reset after upgrade.

LTS Version Updates

Minor LTS releases (3.20.07.5, 3.20.10.5, 3.21.02.2) address issues like out‑of‑order lastInsertId, thread leaks, OOM with slow‑log, table consistency checks, read/write separation message order errors, autocommit anomalies, and occasional ArrayIndexOutOfBoundsException.

For more details, refer to the official GitHub repository, documentation site, and the provided tutorial videos.