4paradigm / 4paradigm/OpenMLDB

window project over limit clause is not supported

Open
#2,457 2 comments 0 reactions 1 assignee Claimed by @aceforeverd View on GitHub
enhancement execute-engine
Dominant language
C++
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Forks
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Avg merge
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Merged PRs (30d)
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Description

since fdfd1f29c6b0ed46a822afdd459ea17f567ccd66, window project over limit clause is not supported. Because `LimitTableHandler` is not seekable: https://github.com/4paradigm/OpenMLDB/blob/5ac4667d0e71dc803ddbd04928bc4681b5ba84b6/hybridse/src/vm/catalog_wrapper.h#L444-L448

This kind SQL might not correct.
```sql
select id, count(col) over w from (select * from t1 limit 10) window w as (....)
```

Contributor guide

Open the contributing guide

Research direction

The issue points to a specific commit and the LimitTableHandler in hybridse/src/vm/catalog_wrapper.h lines 444-448. First, understand why LimitTableHandler is not seekable and how it affects window functions over a LIMIT clause. Review the SQL example and the surrounding window function implementation. Check test files for window project and limit clause usage to see what 'done' looks like.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp, sql
Domain
databases, machine-learning
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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