ClickHouse/docs/changelogs/v21.4.6.55-stable.md

ClickHouse release v21.4.6.55-stable FIXME as compared to v21.4.5.46-stable

Improvement

• Backported in #23679: Fixed quantile(s)TDigest. Added special handling of singleton centroids according to tdunning/t-digest 3.2+. Also a bug with over-compression of centroids in implementation of earlier version of the algorithm was fixed. #23314 (Vladimir Chebotarev).

Bug Fix

• Backported in #23580: Fixed very rare race condition on background cleanup of old blocks. It might cause a block not to be deduplicated if it's too close to the end of deduplication window. #23301 (Alexander Tokmakov).
• Backported in #23676: Don't relax NOT conditions during partition pruning. This fixes #23305 and #21539. #23310 (Amos Bird).
• Backported in #23583: * Fix bug in dict join with join_algorithm = 'auto'. Close #23002. #23312 (Vladimir C).
• Backported in #23641: Fix incompatible constant expression generation during partition pruning based on virtual columns. This fixes https://github.com/ClickHouse/ClickHouse/pull/21401#discussion_r611888913. #23366 (Amos Bird).
• Backported in #23586: Allow to move more conditions to PREWHERE as it was before version 21.1. Insufficient number of moved condtions could lead to worse performance. #23397 (Anton Popov).
• Backported in #23588: Fixed Cannot unlink file error on unsuccessful creation of ReplicatedMergeTree table with multidisk configuration. This closes #21755. #23433 (Alexander Tokmakov).
• Backported in #23591: Fix corner cases in vertical merges with ReplacingMergeTree. In rare cases they could lead to fails of merges with exceptions like Incomplete granules are not allowed while blocks are granules size. #23459 (Anton Popov).
• Backported in #23611: Fix restart / stop command hanging. Closes #20214. #23552 (filimonov).
• Backported in #23693: Fixed server fault when inserting data through HTTP caused an exception. This fixes #23512. #23643 (Nikita Mikhaylov).
• Backported in #23695: Added an exception in case of completely the same values in both samples in aggregate function mannWhitneyUTest. This fixes #23646. #23654 (Nikita Mikhaylov).
• Backported in #23774: Avoid possible "Cannot schedule a task" error (in case some exception had been occurred) on INSERT into Distributed. #23744 (Azat Khuzhin).