codeAnqiang-ma opened a new pull request, #24324:
URL: https://github.com/apache/datafusion/pull/24324
## Which issue does this PR close?
N/A — documentation-only correction; no open issue tracks it.
## Rationale for this change
The user guide for `signum` says "Zero and positive numbers return `1`", but
`signum(0)` returns `0` — the documented return value for zero is the
opposite
of what the function does. The repository's own tests already pin the real
behavior:
- `datafusion/sqllogictest/test_files/scalar.slt`:
`select signum(-2), signum(0), signum(2);` → `-1 0 1`
- The unit tests in `signum.rs` assert `signum(±0.0) == 0.0`
That behavior is intentional: it matches PostgreSQL `sign()` and Spark
`signum()`, and was changed on purpose in #11580 (issue #11557). Only the
docs
were left describing the pre-#11580 behavior, so this PR updates the docs,
not
the code.
## What changes are included in this PR?
Documentation only:
- Update the `#[user_doc]` description in
`datafusion/functions/src/math/signum.rs`
to state that zero returns `0`.
- Regenerate `docs/source/user-guide/sql/scalar_functions.md` via
`dev/update_function_docs.sh`.
## Are these changes tested?
No new tests: the corrected wording describes behavior the existing tests
above
already assert, and those are what it was checked against.
- `cargo test -p datafusion-functions --lib math::signum` → 2 passed
- `cargo fmt --all -- --check` and `./ci/scripts/doc_prettier_check.sh` →
clean
## Are there any user-facing changes?
Yes, documentation only. No API or runtime behavior change.
---
Prepared with AI assistance; every claim above was verified locally against
the
repository's existing tests before opening this PR.
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