DBLE 3.20.10.0 Release Notes – New Features, Improvements, and Bug Fixes

DBLE 3.20.10.0 release notes provide an overview of the open‑source distributed middleware, its project background, and the main updates in this fourth 2020 release.

Project Introduction

DBLE is an enterprise‑grade open‑source distributed middleware, nicknamed “MyCat Plus”, known for its simplicity, stability, active maintenance, strong community support, and extensive user base.

Official project: https://github.com/actiontech/dble

Official documentation (updated): https://actiontech.github.io/dble-docs-cn

New Version Main Updates

This release adds 5 new or refactored features, fixes 24 defects, and includes 1 backward‑compatibility adjustment.

1. Management‑Port Access to DBLE State

The dble_information schema provides tables describing internal metadata. After connecting to the management port, execute use dble_information to query these tables.

Supported operations include SELECT projection, WHERE filtering, JOINs, sub‑queries, aggregation, ordering, scalar functions, and limited INSERT/UPDATE/DELETE.

Example commands:

use dble_information

show tables [ like ]

desc|describe table xxx

show databases

(different from show @@database)

2. Read/Write Splitting

Version 3.20.10.0 supports pure read/write splitting, which can be used independently of the sharding feature. Earlier versions also supported read/write splitting when sharding was enabled.

Full Release Notes

Features

[#1987] Added dble_information schema accessible via the management port for DQL inspection.

[#2075] Alpha support for read/write splitting without sharding.

[#1987] Expanded whiteIP format support.

[#2013] Added manager command to refresh connection pools.

[#2015] Enabled clientFoundRows configuration.

Bug Fixes

[#2225] Corrected sending of select ... for update statements to the master.

[#2042] Fixed incorrect EXPLAIN results when AND conditions contain nested OR.

[#1851] Resolved split import failure caused by split in view sharding tables.

[#2180] Fixed incorrect results when DBLE functions involve UTF‑8.

[#2024] Fixed JDBC batch insert errors with PreparedStatement.clearBatch() and conn.commit().

[#1839] Prevented hangs after setting session transaction isolation level.

[#2166] Handled semicolons inside strings during split processing.

[#1855] Resolved Navicat15 connection errors.

[#2158] Fixed routing errors for simple queries with type conversion.

[#2143] Prevented garbled results when sharding column is decimal.

[#1997] Reported error for hexadecimal literals in string sharding values.

[#1924] Disallowed unsupported ALTER TABLE ... COMMENT = statements.

[#2063] Fixed view creation exception when sub‑query column is * in UNION.

[#2135] Resolved view deletion failure when view name includes schema.

[#1994] Fixed "column not found" errors when alias contains single quotes.

[#2147] Fixed exceptions for select ... information_schema.columns ... with alias queries.

[#2153] Corrected routing to all nodes when partition column value is empty string.

[#2026] Added proper error for unsupported minus operator.

[#2112] Adjusted manager command timeout handling (30 s vs. actual >5 min).

[#2073] Fixed NPE caused by complex GROUP BY HAVING query.

[#2162] Added support for INSERT ... SELECT LEFT JOIN.

[#1806] Fixed incorrect results when multiple user variables depend on each other.

[#2108] Fixed inability to drop views in vertical mode schemas.

[#1961] Strengthened validation for show database statements.

Backward Compatibility Break

[#2031] Removed ROLLBACK command from the management interface.

Reference Links

Reference 1: 2.001 manager_dble_information

Reference 2: 2.03 RW_Split

Reference 3: 1.03 whiteIP

Reference 4: 2.1.21 fresh_conn

Reference 5: 2.2.6 cap_client_found_rows

Past Version Updates

2.19.11.4 – Fixed Chinese character garbling and left‑join issues in sharded tables.

2.20.04.4 – Same fixes plus NPE on reload @@config_all.

3.20.07.2 – Additional fixes for Chinese garbling, left‑join, HA command bugs, show @@dbInstance column display, sqlMaxLimit, and cluster issues.

For more articles about DBLE, follow the official WeChat public account and check the “Community Information – Open‑Source Products” menu.