Problemsby GlyphClickHouse fails to return valid structured output
2 posts from 1 person1d activeFading, +0 this weekunverified
Posts per day
The posts behind it
formatQueryFromJSON rejects parseQueryToJSON output for a partially named Tuple(...) type (empty element name)
`formatQueryFromJSON` refuses `parseQueryToJSON`'s own output when a `Tuple(...)` type names only some of its elements. `ASTTupleDataType::writeJSON` writes empty names as they are, but `readJSON` throws for any empty name. ### Reproduce (release build) ### Cause...
formatQueryFromJSON rejects parseQueryToJSON output for TTL expr GROUP BY without grouping keys
`formatQueryFromJSON` refuses `parseQueryToJSON`'s own output for a `TTL expr GROUP BY` without grouping keys. `MergeTree` accepts an empty `GROUP BY` on a TTL element (aggregates the whole part), and the parser and formatter handle it, but the JSON reader rejects it. ###...
Companies and products named
About this problem
Evidence
2 posts from 1 person in 1 place, about 2 a week over 1 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 "structured-output" rule about ClickHouse. First post Sep 22, 2026, latest Sep 22, 2026. Unverified: fewer than 3 posts, or one person or place only. Method
The same problem elsewhere
Models fail to return valid structured output
17 posts from 15 people on GitHub issues, Hacker News.
OpenAI fails to return valid structured output
12 posts from 12 people on GitHub issues, Hacker News.
Claude fails to return valid structured output
10 posts from 8 people on GitHub issues.
Codex fails to return valid structured output
6 posts from 3 people on GitHub issues.
Anthropic fails to return valid structured output
5 posts from 5 people on GitHub issues.
LlamaIndex fails to return valid structured output
5 posts from 5 people on GitHub issues.
Model Context Protocol fails to return valid structured output
5 posts from 5 people on GitHub issues, Reddit.
Ollama fails to return valid structured output
4 posts from 3 people on GitHub issues.
Mistral fails to return valid structured output
3 posts from 3 people on GitHub issues.
GitHub fails to return valid structured output
3 posts from 3 people on GitHub issues.
Gemini fails to return valid structured output
3 posts from 3 people on GitHub issues, Reddit.
vLLM fails to return valid structured output
3 posts from 3 people on GitHub issues.
Other ClickHouse problems
ClickHouse upgrades break working setups
31 posts from 20 people on GitHub issues.
ClickHouse users keep filing bugs
Top post: "Tighten seccomp policy for optional kernel interfaces", one of 19 posts from 8 people on GitHub issues.
Trouble with ClickHouse column
Top post: "MaterializedPostgreSQL: reading a Nullable column's .null subcolumn (x IS NULL, count(x)) fails with", one of 15 posts from 9 people on GitHub issues.
ClickHouse costs outgrow the value it gives
11 posts from 3 people on GitHub issues.
Trouble with ClickHouse table
Top post: "`SYSTEM RESTORE REPLICA` on a second replica over-bumps the table `metadata` znode version; every later", one of 8 posts from 5 people on GitHub issues.
Experiments on ClickHouse are hard to reproduce and track
8 posts from 1 person on GitHub issues. Unverified.
Trouble with ClickHouse tables
Top post: "Paimon: resolve columns by field id, so tables with renamed or re-added columns are readable", one of 7 posts from 6 people on GitHub issues.
Trouble with ClickHouse join
Top post: "Explicit grace_hash now spills at max_bytes_ratio_before_external_join = 0.5 although the build side fits in", one of 5 posts from 4 people on GitHub issues.
ClickHouse error messages are cryptic
5 posts from 3 people on GitHub issues.
Trouble with ClickHouse read
Top post: "ORC: a corrupt PostScript `metadata_length` makes ORC predicate pushdown read `stripe_stats` out of bounds,", one of 4 posts from 4 people on GitHub issues.
Trouble with ClickHouse database
Top post: "`DROP NAMED COLLECTION` succeeds while a database uses the collection, and the server then fails to start", one of 4 posts from 2 people on GitHub issues.
Trouble with ClickHouse query
Top post: "Memory tracker counts jemalloc's freed pages as used, so a heavy query started right after another spills to", one of 4 posts from 3 people on GitHub issues.
History