ClickHouse/docs/changelogs/v21.8.6.15-lts.md

ClickHouse release v21.8.6.15-lts FIXME as compared to v21.8.5.7-lts

Improvement

• Backported in #28899: Use real tmp file instead of predefined "rows_sources" for vertical merges. This avoids generating garbage directories in tmp disks. #28299 (Amos Bird).
• Backported in #28642: Fix strange sessions expiration logic in Keeper. Probably it should help in CI: https://clickhouse-test-reports.s3.yandex.net/0/6bd9b82141c98dcd7796fd9d08326831095ba519/stress_test_(debug).html#fail1. #28519 (alesapin).
• Backported in #28718: To be added. Closes #28529. #28614 (Kseniia Sumarokova).

Bug Fix

• Backported in #27923: Fix PostgreSQL-style cast (:: operator) with negative numbers. #27876 (Anton Popov).
• Backported in #28753: Fix transformation of disjunctions chain to IN (controlled by settings optimize_min_equality_disjunction_chain_length) in distributed queries with settings legacy_column_name_of_tuple_literal = 0. #28658 (Anton Popov).

Bug Fix (user-visible misbehaviour in official stable or prestable release)

• Backported in #28644: Fix rare case when changes of clickhouse-keeper settings may lead to lost logs and server hung. #28360 (alesapin).
• Backported in #28508: Fix lack of quotes for table names in MaterializedPostgreSQL engine. Closes #28316. #28433 (Kseniia Sumarokova).
• Backported in #28510: Fixed possible ZooKeeper watches leak on background processing of distributed DDL queue. Closes #26036. #28446 (Alexander Tokmakov).
• Backported in #28573: Fix bug which can lead to error Existing table metadata in ZooKeeper differs in sorting key expression. after alter of ReplicatedVersionedCollapsingMergeTree. Fixes #28515. #28528 (alesapin).
• Backported in #28597: Fix There is no subcolumn error, while select from tables, which have Nested columns and scalar columns with dot in name and the same prefix as Nested (e.g. n.id UInt32, n.arr1 Array(UInt64), n.arr2 Array(UInt64)). #28531 (Anton Popov).
• Backported in #28714: Add Settings.Names, Settings.Values aliases for system.processes table. #28685 (Vitaly Orlov).
• Backported in #28741: Fix the coredump in the creation of distributed tables, when the parameters passed in are wrong. #28686 (Zhiyong Wang).
• Backported in #28791: Fix benign race condition in ReplicatedMergeTreeQueue. Shouldn't be visible for user, but can lead to subtle bugs. #28734 (alesapin).
• Backported in #28994: Fixed a race condition between DROP PART and REPLACE/MOVE PARTITION that might cause replicas to diverge in rare cases. #28864 (Alexander Tokmakov).
• Backported in #28948: Fix reading of subcolumns from compact parts. #28873 (Anton Popov).
• Backported in #28930: Fix higher-order array functions (SIGSEGV for arrayCompact/ILLEGAL_COLUMN for arrayDifference/arrayCumSumNonNegative) with consts. #28904 (Azat Khuzhin).