james-willis opened a new pull request, #1099:
URL: https://github.com/apache/sedona-db/pull/1099
## Summary
- Adds `RS_Min_Agg` / `RS_Max_Agg`, native Rust aggregate UDFs computing the
pixel-wise min/max raster across a group of rasters.
- One generic `SedonaAccumulator`/`Accumulator` pair
(`RasterMinMaxAgg`/`MinMaxAccumulator`), parametrized by a
`MinMaxOp::{Min,Max}` comparator, to avoid duplicating logic between the two
functions.
- Nodata-aware: a pixel equal to a band's nodata sentinel is treated as
absent rather than a comparable value — the other raster's value wins outright,
and a pixel that's nodata in every raster in the group stays nodata.
- State is the output raster type itself (min/max combine is associative and
idempotent, so the running combined raster is valid partial state), which lets
`update_batch` and `merge_batch` share one implementation.
- Validates that every raster combined within a group shares band count,
dimension names, shape, data type, and nodata value, returning a clean
execution error (not a panic) on mismatch.
- Registered in `sedona-raster-functions`'s aggregate UDF set; docs added at
`docs/reference/sql/rs_min_agg.qmd` and `rs_max_agg.qmd`.
**v1 scope**, called out in the code:
- Plain `Accumulator` only — no `GroupsAccumulator` yet (DataFusion falls
back to one accumulator per group, which is correct but not the fastest path
for many small groups).
- Single raster argument.
- Requires bands to be contiguous (uses `NdBuffer::as_contiguous`);
non-contiguous inputs should go through `RS_EnsureContiguous` first.
This is the first of a small family of raster statistics aggregates
(mean/sum/std/var/median tracked separately); min/max are the easiest to make
exactly and cheaply distributable.
## Test plan
- [x] `cargo test -p sedona-raster-functions` — 261 passed (7 new: basic
min/max, nodata skip, cross-batch state merge, null-batch, mismatched-shape
error), no regressions
- [x] `cargo build -p sedona-raster-functions`
- [x] `cargo fmt -p sedona-raster-functions`
- [x] `cargo clippy -p sedona-raster-functions --all-targets` — clean
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