TL;DR Yes, ClickHouse fully supports UPDATEs. As of April 2026, ClickHouse ships standard SQL UPDATE ... SET ... WHERE syntax that runs in milliseconds, alongside four other update mechanisms: ALTER TABLE … UPDATE mutations for bulk operations, lightweight DELETE, on-the-fly mutation visibility, and ReplacingMergeTree for high-volume upserts and CDC. The "ClickHouse is append-only" claim is outdated by eight years and 100+ merged pull requests. Key facts: Standard SQL UPDATE shipped in ClickHouse 25.7 (July 2025) via PR #82004 , backed by a new "patch part" architecture. It was promoted to Beta with default enablement in version 25.8 ( PR #85952 ). Lightweight UPDATE delivers up to 1,000× to 2,400× speedup for single-row updates compared to classical mutations, per ClickHouse's own benchmarks. Patch parts store only the changed columns plus five system columns, with no part rewrite. ALTER TABLE … UPDATE has shipped since August 2018 (ClickHouse v18.12), authored by Alex Zatelepin ( ztlpn ).…