v.20.4Improvement

Remove ORDER BY from Mutations and Ensure Row Order Compliance

Official CH changelog text
Remove ORDER BY stage from mutations because we read from a single ordered part in a single thread. Also add check that the rows in mutation are ordered by sorting key and this order is not violated. #9886 (alesapin)
Remove the ORDER BY stage from mutations in ClickHouse, enforcing that mutation rows must be ordered by the sorting key without order violations.

Why it matters

This feature optimizes mutation processing by eliminating the unnecessary ORDER BY stage, as mutations read from a single ordered part in a single thread. It also improves data integrity by adding a check that ensures mutation rows are correctly ordered by the sorting key.

How to use it

Users do not need to explicitly enable this feature; it is applied automatically during mutations. Ensure that mutation rows are provided in order by the sorting key to avoid errors.

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