ClickHouse/docs/changelogs/v20.5.2.7-stable.md

ClickHouse release v20.5.2.7-stable FIXME as compared to v20.5.1.3833-prestable

New Feature

• Add Alter table drop replica replica_name support. This fixes #7080. #10679 (sundyli).

Improvement

• Add number of errors to ignore while choosing replicas (distributed_replica_error_ignore). #11669 (Azat Khuzhin).
• Multiversion metadata for storages without structure locks. #11745 (alesapin).
• Slightly relax the validation of ODBC connection string. If the hostname or username contains only word characters along with . and -, don't put it into curly braces. It is needed, because some ODBC drivers (e.g. PostgreSQL) don't understand when hostname is enclosed in curly braces. #11845 (Alexey Milovidov).
• Support SIGNED and UNSIGNED modifiers of standard integer types (BIGINT, INT, ...) for compatibility with MySQL. #11858 (Alexander Tokmakov).
• Allow to use sumWithOverflow as SimpleAggregateFunction. Closes #8053. #11865 (Alexander Kuzmenkov).
• Add FixedString support in Hashing functions. #11878 (flynn).

Bug Fix

• Fix unexpected behaviour of queries like SELECT *, xyz.* which were success while an error expected. #11753 (hexiaoting).
• Fix wrong result for if() with NULLs in condition. #11807 (Artem Zuikov).
• Fix memory accounting via HTTP interface (can be significant with wait_end_of_query=1). #11840 (Azat Khuzhin).
• Fix rare crash caused by using Nullable column in prewhere condition. Continuation of #11608. #11869 (Nikolai Kochetov).
• Backported in #11965: Fix potential floating point exception when parsing DateTime64. This fixes #11374. #11875 (Alexey Milovidov).
• Fix potential floating point exception when parsing DateTime64. This fixes #11374. #11875 (Alexey Milovidov).
• Backported in #11963: Use the correct current database for checking access rights after statement USE database. #11920 (Vitaly Baranov).
• Backported in #12059: Fix incorrect comparison of tuples with Nullable columns. Fixes #11985. #12039 (Nikolai Kochetov).

Build/Testing/Packaging Improvement

• Add simple GitHub hook script for the serverless environment. #11605 (alesapin).
• Send logs to client on fatal errors if possible. This will make test results more readable. #11826 (Alexey Milovidov).
• Allow ClickHouse to run on Android. #11894 (Alexey Milovidov).

NO CL ENTRY

• NO CL ENTRY: 'Merging #10679'. #11896 (Alexander Tokmakov).
• NO CL ENTRY: 'Cherry pick #11875 to 20.5: Fix strange and wrong code around DateTime64'. #11958 (Ivan).