v.19.6
Backward Incompatible Changes
1Bug Fixes
12- Fixed Potential Null Pointer Dereference in Clickhouse-copier
- Fixed Error on Query with JOIN + ARRAY JOIN #4938 (artem Zuikov)
- Fixed Hanging on Start of the Server When a Dictionary Depends on Another Dictionary via a Database with Engine=dictionary
- Partially Fix Distributed_product_mode = Local
- Fix Potentially Wrong Result for SELECT DISTINCT with JOIN #5001 (artem Zuikov)
- Fixed Very Rare Data Race Condition That Could Happen When Executing a Query with UNION ALL Involving at Least Two Selects from System.columns, System.tables, System.parts, System.parts_tables or Tables of Merge Family and Performing ALTER of Columns of the Related Tables Concurrently
- Fixed IN Condition Pushdown for Queries from Table Functions Mysql and Odbc and Corresponding Table Engines
- Fix Deadlock in Zookeeper
- Allow Quoted Decimals in CSV
- Disallow Conversion from Float Inf/nan into Decimals (throw Exception)
- Fix Data Race in Rename Query
- Temporarily Disable Lfalloc
Build/Testing/Packaging Improvements
6- Fixed Test Failures When Running Clickhouse-server on Different Host #4713 (vasily Nemkov)
- Clickhouse-test: Disable Color Control Sequences in Non Tty Environment
- Clickhouse-test: Allow Use Any Test Database (remove Test
- Fix Ubsan Errors #5037 (vitaly Baranov)
- Yandex Lfalloc Was Added to Clickhouse to Allocate Markcache and Uncompressedcache Data in Different Ways to Catch Segfaults More Reliable #4995 (danila Kutenin)
- Python Util to Help with Backports and Changelogs
Experimental Features
1Improvements
6- Added Support for Non-constant and Negative Size and Length Arguments for Function Substringutf8
- Disable Push-down to Right Table in Left Join, Left Table in Right Join, and Both Tables in Full Join
- Clickhouse-copier: Auto Upload Task Configuration from --task-file Option #4876 (proller)
- Added Typos Handler for Storage Factory and Table Functions Factory
- Support Asterisks and Qualified Asterisks for Multiple Joins Without Subqueries #4898 (artem Zuikov)
- Make Missing Column Error Message More User Friendly
New Features
4- TTL Expressions for Columns and Tables
- Added Support for Brotli Compression for HTTP Responses (accept-encoding: Br) #4388 (mikhail)
- Added New Function Isvalidutf8 for Checking Whether a Set of Bytes Is Correctly Utf-8 Encoded
- Add New Load Balancing Policy First_or_random Which Sends Queries to the First Specified Host and If It's Inaccessible Send Queries to Random Hosts of Shard