jk-shah opened a new issue, #41043:
URL: https://github.com/apache/beam/issues/41043
### What happened?
In Beam YAML, `Filter` with `language: generic` documents support for `==`,
`<=`, `>=`, `<`, `>`, and `!=` comparisons (`validate_generic_expression` in
`sdks/python/apache_beam/yaml/yaml_mapping.py` checks `cmp in {'==', '<=',
'>=', '<', '>', '!='}`), but any two-character comparison operator (`>=`, `<=`,
`==`, `!=`) is rejected at pipeline validation time with `ValueError`:
```yaml
pipeline:
type: chain
transforms:
- type: Create
config:
elements:
- {id: 1, name: Ada, age: 36}
- {id: 2, name: Linus, age: 17}
- type: Filter
config:
language: generic
keep: "age >= 21"
- type: LogForTesting
```
Running this pipeline fails with:
```text
ValueError: Missing language specification, unknown input fields, or invalid
generic expression: age >= 21. The given input fields are ['id', 'name',
'age']. See https://beam.apache.org/documentation/sdks/yaml-udf/#generic
```
Only single-character operators (`<` and `>`) succeed.
### Cause
In `sdks/python/apache_beam/yaml/yaml_mapping.py`,
`validate_generic_expression` splits comparison expressions using a greedy left
group:
```python
if allow_cmp:
maybe_cmp = re.fullmatch('(.*)([<>=!]+)(.*)', expr)
if maybe_cmp:
left, cmp, right = maybe_cmp.groups()
if (is_atomic(left.strip()) and is_atomic(right.strip()) and
cmp in {'==', '<=', '>=', '<', '>', '!='}):
return
```
Because `(.*)` is greedy and `[<>=!]+` only requires at least one character,
`'age >= 21'` is split into:
- `left = 'age >'` (which fails `is_atomic(left.strip())`)
- `cmp = '='` (which is not in `{'==', '<=', '>=', '<', '>', '!='}`)
- `right = ' 21'`
Making the left group non-greedy (`(.*?)`) keeps multi-character operators
intact.
### Issue Priority
Priority: 2 (default / most bugs should be filed as P2)
### Issue Components
- [x] Component: Python SDK
- [ ] Component: Java SDK
- [ ] Component: Go SDK
- [ ] Component: Typescript SDK
- [ ] Component: IO connector
- [ ] Component: Beam YAML
- [ ] Component: Beam examples
- [ ] Component: Beam playground
- [ ] Component: Beam katas
- [ ] Component: Website
- [ ] Component: Infrastructure
- [ ] Component: Spark Runner
- [ ] Component: Flink Runner
- [ ] Component: Prism Runner
- [ ] Component: Hazelcast Jet Runner
- [ ] Component: Google Cloud Dataflow Runner
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