4paradigm / 4paradigm/OpenMLDB

can't lift child `i` to list for udf functions which requires params as list

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#3,039 0 comments 0 reactions 1 assignee Claimed by @aceforeverd View on GitHub
bug execute-engine
Dominant language
C++
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Merged PRs (30d)
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Description

some udf function requires list param, e.g `lag`, `first_value`, `join`, while some exprs can't infer to list, e.g `case when` expr.

A yaml case:

```yaml
- id: 22
inputs:
- name: t1
columns: ["id string", "gp int", "ts int64", "val int"]
indexs: ["index1:gp:ts"]
rows:
- ["0", 1, 5, 66]
- ["1", 1, 6, 67]
sql: |
select id,
lag(case when ts < 10 then ts else null end, 1) over w as agg
from t1
WINDOW w AS (PARTITION BY gp ORDER BY ts ROWS_RANGE BETWEEN 60d PRECEDING AND CURRENT ROW MAXSIZE 101)
expect:
success: true
```

Contributor guide

Open the contributing guide

Research direction

The issue involves UDF functions like `lag` that require list parameters, but certain expressions like `case when` cannot be inferred to a list. Examine the SQL engine's type inference logic, particularly around window functions and expression evaluation. Look at the test case in YAML to understand the failing scenario. Check the code handling UDF parameter lifting and expression type resolution.

Written by the indexing model from the issue text.

Assessment

Tech stack
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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