Can ClickHouse Delete Data? Debunking the "Append-Only" Myth

Can ClickHouse delete data? Despite the "ClickHouse is append-only / immutable" reputation, ClickHouse has supported DELETE since 2018 — and in 2026 it ships four production-grade delete paths. This is a PR-by-PR reality check on the most persistent ClickHouse DELETE myth.

We trace eight years and 80+ merged pull requests across five eras: heavyweight ALTER TABLE DELETE (2018), lightweight DELETE FROM (v22.8), GA + the retirement of allow_experimental_lightweight_delete (v23.3), storage-aware merges that stop deleted rows from lingering (2024), and patch parts that make deletes almost free (v25.7). We also cover DROP PARTITION for bulk deletes, ReplacingMergeTree with the is_deleted column, and why the "FINAL is too slow" critique is outdated.

If you're evaluating ClickHouse, migrating from Postgres/MySQL/Snowflake, or just tired of hearing "you can't delete in ClickHouse," this video gives you the version numbers and PRs to back every claim.

⏱️ Chapters
0:00 Can ClickHouse really not delete?
0:45 Where the "append-only" FUD comes from
1:30 The 6 ClickHouse DELETE myths
2:10 Era 1 (2018): Mutations — when the FUD was true
3:05 Era 2 (2022): Lightweight DELETE changes everything
4:25 Era 3 (2023): GA & the experimental flag is dead
5:30 Era 4 (2024): Deleted rows stop lingering
6:25 Era 5 (2025–26): Patch parts & on-the-fly deletes
7:25 DROP PARTITION, ReplacingMergeTree & FINAL
8:20 The full 2018–2026 timeline
8:50 Which delete method to use when
9:25 How to respond to "ClickHouse can't delete"
9:45 Test it on your workload

🔗 Full PR-by-PR write-up: https://dev.to/manveer_chawla_64a7283d5a/can-clickhouse-delete-data-a-2026-pr-by-pr-analysis-58in

Topics: ClickHouse DELETE, lightweight delete, DELETE FROM, ALTER TABLE DELETE, ReplacingMergeTree, is_deleted, patch parts, DROP PARTITION, mutations, FINAL, OLAP database, real-time analytics.

#ClickHouse #DataEngineering #Database #Analytics #SQL

Видео Can ClickHouse Delete Data? Debunking the "Append-Only" Myth канала Data Operations Guide