ClickHouse hits connection, locking and scaling limits

Databases2 posts from 2 people2d active+00 posts in the last 7 days, 0 the 7 days before (fading)Unverified

Posts per day2 posts, Sep 21 to Oct 21

The posts behind it

2, newest first

GitHub issuesOct 5 Concurrent partition-scoped ALTERs deadlock the replication queue forever via max_replicated_mutations_in_queue**TL;DR:** Two concurrent partition-scoped `ALTER`s that each carry a metadata command plus a data mutation can deadlock the replication queue of a `ReplicatedMergeTree` table permanently. The later alter's `MUTATE_PART` entries fill the queue up to...ClickHouse/ClickHouse · zlareb1Open ↗GitHub issuesSep 21 Stress test `Hung check` fails without finding a hung query: the check's own `system.stack_trace` query queues behind another reader of itThe `Hung check` at the end of `Stress test` regularly fails without ever naming a hung query. Over the last 30 days it failed 274 times on `master` or on pull requests targeting it, 69 of those in `Stress test (arm_msan)` alone (20 of them on `master` itself, spread over 22...ClickHouse/ClickHouse · alexey-milovidovOpen ↗

Companies and products named

Named2 posts

ClickHouse

About this problem

Evidence

2 posts from 2 people in 1 place, about 1 a week over 15 days. Mostly on ClickHouse/ClickHouse.

Frustration Frustration 3 of 3· Seen on GitHub issues

How it was grouped

Posts that state a pain and match the "db-scaling" rule about ClickHouse. First post Sep 21, 2026, latest Oct 5, 2026. Unverified: fewer than 3 posts, or one person or place only. Method

The same problem elsewhere

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History

MomentumOct 12, 2026steady to fading

AddedOct 9, 2026ClickHouse hits connection, locking and scaling limits (2 posts)