v.18.12
Backward Incompatible Changes
2Bug Fix
29- Fixed Dictionary Tables Exception in Version 18.10.3
- Fixed bug in merging CollapsingMergeTree tables with empty data parts using vertical algorithm
- Fixed Race Condition in Memory Tables During DROP or TRUNCATE Operations
- Fixed Data Loss Issue in Replicated Tables Due to Expired Session Error
- Fixed segfault in JOIN ON operation
- Fixed Error in Column Name Search for Qualified Columns in WHERE Expression
- Fixed "Not found column" error in distributed queries with IN subquery
- Fixed Block Structure Mismatch Error in UNION Stream for Distributed Queries
- Fixed pointInPolygon for Non-Convex Polygons
- Fixed nan Comparison with Integers
- Fixed rare segfault error in zlib-ng library
- Fixed memory leak in table insertion with complex AggregateFunction columns
- Fixed Race Condition in Buffer and MergeTree Table Operations
- Fixed segfault issue when comparing non-trivial tuples
- Fixed Segfault in ON CLUSTER Queries
- Fixed Error in arrayDistinct Function for Nullable Array Elements
- Enable Optimize Predicate Expression Supports SELECT *
- Fixed segfault on ZooKeeper session re-initialization
- Fixed ZooKeeper Blocking Issue
- Fixed Nested Data Structure Handling in SummingMergeTree
- Memory Alignment for Aggregate Function States in ClickHouse
- Added Array Size Check for Nested Type Fields on Insert
- Fixed ODBC External Dictionary Update Error in Version 18.12.13
- Fixed Crash When Creating Temporary Tables with IN Condition
- Fixed Aggregate Functions Error for Arrays with NULL Elements
- Merge Functionality Fixed for Distributed Tables in ClickHouse
- Fixed ClickHouse Compatibility Issue with Older Ubuntu Versions
- Fixed Errors in enable_optimize_predicate_expression Setting
- Fixed Backwards Compatibility Issue in ClickHouse Replica Cloning
Build/Testing/Packaging Improvement
6Experimental Feature
2Improvement
28- Fixed Replication Log Accumulation and Added Recovery Mode for Lagging Replicas
- Improved GROUP BY Performance with Mixed Aggregation Fields
- Improved PREWHERE Performance and Expression Transfer
- Improved Parsing Performance for CSV and TSV Formats
- Improved Binary Format Performance for Strings and Arrays
- Increased Query Performance and Reduced Memory for Large Table Count in system.tables and system.columns
- Fixed Performance Issue with Large Error-Inducing Query Streams
- Conditions Cast into View with Predicate Expression Optimization Enabled
- Improvements to UUID Data Type Functionality
- UUID Data Type Supported in The-Alchemist Dictionaries
- VisitParamExtractRaw Function Handles Nested Structures Correctly
- Fix for Skipping Unknown Fields in JSONEachRow Format with input_format_skip_unknown_fields Enabled
- CASE Expression Now Allows Omitting ELSE Clause
- Operation Timeout Configuration for ZooKeeper
- Specifying Offset in LIMIT Clause
- Using SELECT TOP n as an Alternative to LIMIT
- Increased System Table Queue Size to Reduce Full Queue Errors
- windowFunnel Aggregate Function Enhancements
- Duplicate Columns in USING Clause for JOIN
- Pretty Formats Limit Column Alignment by Width
- odbc Function Enhanced with Database/Schema Name Specification
- Added Username Support from ClickHouse Client Config File
- ZooKeeperExceptions Counter Split into User, Hardware, and Other Categories
- ALTER DELETE Queries for Materialized Views
- Added Randomization to Cleanup Thread for ReplicatedMergeTree Tables
- Support for ATTACH TABLE ... ON CLUSTER Queries
- Data Parts Unchanged During Mutation Are Not Downloaded by Replicas
- Autocomplete for Settings in ClickHouse Client
New Feature
30- Added DECIMAL Data Type Support in ClickHouse
- New WITH ROLLUP Modifier for GROUP BY
- Asterisk Behavior in JOIN Queries and Configuration Adjustment in SQL
- Added JOIN Support for Table Functions
- Autocomplete with Tab in ClickHouse Client
- Ctrl+C in ClickHouse Client Clears Entered Query
- Added join_default_strictness Setting for JOIN Operations
- Server Log Query ID Display
- Ability to Obtain Query Execution Logs in ClickHouse Client
- New Logging for Query Settings in system.query_log and system.processes Tables
- System Query Log and Processes Tables Updated with Thread Count Information
- Added ProfileEvents Counters for Network and Disk I/O Measurements
- Added ProfileEvents Counters for System Metrics and Taskstats Information
- ProfileEvents Counters for Detailed Query Resource Consumption
- Added system.query_thread_log Table and log_query_threads Setting
- System Metrics and Events Tables Gain Built-in Documentation
- Added arrayEnumerateDense Function
- Added arrayCumSumNonNegative and arrayDifference Functions
- Added retention aggregate function
- Enhancements to Aggregate Functions: Merging and Scaling States
- Tables in MergeTree Family Gain Virtual Column _partition_id
- Added Support for ALTER UPDATE Queries
- Added allow_ddl Option to Restrict DDL Query Access
- Added min_merge_bytes_to_use_direct_io Option for MergeTree Engines
- System Table Updates: Added partition_id Column to system.merges
- Invalidate Query Implementation for ClickHouse Source
- Added Support for UInt, Int, and DateTime as Range Hashed External Dictionary Keys
- Decimal Type Enhancements: Support for var* and stddev* Aggregate Functions
- Decimal Type Enhancements: Support for Mathematical Functions
- system.part_log table adds partition_id column