Problemsby GlyphTrouble with ClickHouse table
8 posts from 5 people5d activeFading, +0 this week
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SYSTEM DROP/PREWARM VECTOR SIMILARITY INDEX CACHE [FOR TABLE db.t] [INDEX idx]
## Problem With one or more tables, each with a `vector_similarity` (HNSW) index it is nice to cleanup each index cache separately. ## Requested 1. **Targeted drop:** `SYSTEM DROP VECTOR SIMILARITY INDEX CACHE [ON CLUSTER c] [FOR TABLE db.t [INDEX idx]]`. Evicts only that...
MySQLDump format misparses `CREATE TABLE IF NOT EXISTS` table name as `IF`
...returns `IF` as the table name and `tryToExtractStructureFromCreateQuery` then fails to parse the remaining `NOT EXISTS t1 (...)`. Analysis details (evidence, affected locations, impact) Why we believe this is a bug: `readFirstCreateAndInsertQueries` (:433) ->...
`SYSTEM RESTORE REPLICA` on a second replica over-bumps the table `metadata` znode version; every later `ALTER` fails with `CANNOT_ASSIGN_ALTER` (26.3+)
...and a server restart do not help. The table serves reads and writes, only `ALTER` is broken. Cause: `restoreMetadataInZooKeeper` raises the `stat.version` of ` /metadata` **by** the max `metadata_version.txt` of the local parts (M), not **to** it. The first restored replica...
`BACKUP` to `File()` on a case-insensitive filesystem: fail on names that differ only in case instead of dropping one silently, as `CREATE TABLE` already does
Detect two names that collide on a case-insensitive filesystem when writing a backup to `File()`, and fail the `BACKUP` (or encode the names so both survive). That lets a `File()` backup taken on macOS restore every table. ClickHouse 26.4.3.37 and master, macOS on APFS...
Cache dictionary table read fabricates a DEFAULT row for a deleted source key
### Describe what's wrong - Reading a `cache`, `complex_key_cache` or `ssd_cache` dictionary as a table can return a row for a key that exists nowhere. - Trigger: a cached cell expires per `LIFETIME` and the key has since been deleted from the source. - Expected: the row is...
Distributed-destination INSERT SELECT still forwards the plain table function
### Describe what's wrong - `INSERT INTO SELECT * FROM url(...)` inserts the source data once per destination shard - Triggered with `parallel_replicas_for_cluster_engines = 1`, `enable_parallel_replicas = 1`, `cluster_for_parallel_replicas` set and...
Wrong results: `variantElement` over a `Merge` table returns `NULL` unless it is in the top-level projection
...`multiIf` into a subquery projection and filtering on its alias in the outer query is a workaround and produces the documented rows. Related: https://github.com/ClickHouse/ClickHouse/issues/121166
clickhouse local: table/dictionary names longer than NAME_MAX raise std::filesystem_error (code 1001) instead of UNKNOWN_TABLE
In `clickhouse local`, any query naming a table or dictionary with more than 255 bytes in its name fails with `std::filesystem_error` (`Code 1001 (STD_EXCEPTION)`) instead of a normal `UNKNOWN_TABLE` / "Dictionary not found". The default database in `clickhouse local` overlays...
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About this problem
Evidence
8 posts from 5 people in 1 place, about 1 a week over 43 days. Mostly on ClickHouse/ClickHouse. Tools named alongside: GitHub, MySQL.
Frustration Frustration 0 of 3· Seen on GitHub issues
How it was grouped
Posts about ClickHouse with no known issue, sharing the word "table". First post Sep 21, 2026, latest Nov 2, 2026. Corroborated: 3 or more posts from 2 or more people or places. Method
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