ClickHouse/docs/changelogs/v21.2.5.5-stable.md

ClickHouse release v21.2.5.5-stable FIXME as compared to v21.2.4.6-stable

Bug Fix

• Backported in #20574: Fix crash which could happen if unknown packet was received from remove query (was introduced in #17868). #20547 (Azat Khuzhin).
• Backported in #21006: Fix 'Empty task was returned from async task queue' on query cancellation. #20881 (Azat Khuzhin).
• Backported in #21132: Fixed behaviour, when ALTER MODIFY COLUMN created mutation, that will knowingly fail. #21007 (Anton Popov).
• Backported in #21251: - Block parallel insertions into storage join. #21009 (Vladimir C).
• Backported in #21069: Out of bound memory access was possible when formatting specifically crafted out of range value of type DateTime64. This closes #20494. This closes #20543. #21023 (Alexey Milovidov).
• Backported in #21160: Fix input_format_null_as_default take effective when types are nullable. This fixes #21116 . #21121 (Amos Bird).
• Backported in #21228: Fixes #21112. Fixed bug that could cause duplicates with insert query (if one of the callbacks came a little too late). #21138 (Kseniia Sumarokova).
• Backported in #21276: Fix bug with join_use_nulls and joining TOTALS from subqueries. This closes #19362 and #21137. #21248 (Vladimir C).