fix(udf): eval_row panic due to misuse of input row as arg row

[xiangjinwu]

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What's changed and what's your intention?

Fixes #9066

    async fn eval_row(&self, input: &OwnedRow) -> Result<Datum> {
        let chunk = DataChunk::from_rows(std::slice::from_ref(input), &self.arg_types);
        let output_array = self.eval(&chunk).await?;

In this previous implementation, it converts an input row to an input chunk and reuses eval. However, the data types of columns are not arg_types. We have to evaluate children expressions to get arrays / datums of arg_types.

This always fails, but the eval_row code path executes rarely, mostly only during stream error tolerating, hash join condition, and frontend constant folding. Similar issues: #8115 (review) #7777

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• I have added necessary unit tests and integration tests
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[xiangjinwu]

With the dummy column, it triggers panic:

thread 'risingwave-streaming-actor' panicked at 'Failed to append datum, array builder type: Utf8, scalar type: Date', src/common/src/array/mod.rs:562:1

Without the dummy column, it triggers panic:

thread 'risingwave-streaming-actor' panicked at 'itertools: .zip_eq() reached end of one iterator before the other', /Users/xiangjin/.cargo/registry/src/index.crates.io-6f17d22bba15001f/itertools-0.10.5/src/zip_eq_impl.rs:48:13

[lmatz]

thanks!

It's really a problem that eval_row() can be hardly covered in normal SLT tests.

😢

[codecov]

Codecov Report

Merging #9240 (c047556) into main (ff8de5c) will decrease coverage by 0.02%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main    #9240      +/-   ##
==========================================
- Coverage   70.83%   70.82%   -0.02%     
==========================================
  Files        1201     1201              
  Lines      200454   200472      +18     
==========================================
- Hits       141992   141976      -16     
- Misses      58462    58496      +34     

Flag	Coverage Δ
rust	70.82% <0.00%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/expr/src/expr/expr_udf.rs	0.00% <0.00%> (ø)

... and 6 files with indirect coverage changes

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[wangrunji0408]

Thanks for the fix. 🥵