feat(rust/sedona-expr): Use Covers filter for ST_Equals for more Geoparquet pruning (#216)

Author: petern48

rust/sedona-expr/src/spatial_filter.rs

@@ -177,7 +177,7 @@ impl SpatialFilter {
         let args = parse_args(raw_args);
         let fun_name = scalar_fun.fun().name();
         match fun_name {
-            "st_intersects" | "st_equals" | "st_touches" | "st_crosses" | "st_overlaps" => {
+            "st_intersects" | "st_touches" | "st_crosses" | "st_overlaps" => {
                 if args.len() != 2 {
                     return sedona_internal_err!("unexpected argument count in filter evaluation");
                 }
@@ -199,6 +199,28 @@ impl SpatialFilter {
                     _ => Ok(Some(Self::Unknown)),
                 }
             }
+            "st_equals" => {
+                if args.len() != 2 {
+                    return sedona_internal_err!("unexpected argument count in filter evaluation");
+                }
+
+                match (&args[0], &args[1]) {
+                    (ArgRef::Col(column), ArgRef::Lit(literal))
+                    | (ArgRef::Lit(literal), ArgRef::Col(column)) => {
+                        if !is_prunable_geospatial_literal(literal) {
+                            return Ok(Some(Self::Unknown));
+                        }
+                        match literal_bounds(literal) {
+                            Ok(literal_bounds) => {
+                                Ok(Some(Self::Covers(column.clone(), literal_bounds)))
+                            }
+                            Err(e) => Err(DataFusionError::External(Box::new(e))),
+                        }
+                    }
+                    // Not between a literal and a column
+                    _ => Ok(Some(Self::Unknown)),
+                }
+            }
             "st_within" | "st_covered_by" | "st_coveredby" => {
                 if args.len() != 2 {
                     return sedona_internal_err!("unexpected argument count in filter evaluation");
@@ -575,15 +597,8 @@ mod test {
     }
 
     #[rstest]
-    fn predicate_from_expr_commutative_functions(
-        #[values(
-            "st_intersects",
-            "st_equals",
-            "st_touches",
-            "st_crosses",
-            "st_overlaps"
-        )]
-        func_name: &str,
+    fn predicate_from_expr_commutative_intersects_functions(
+        #[values("st_intersects", "st_touches", "st_crosses", "st_overlaps")] func_name: &str,
     ) {
         let column: Arc<dyn PhysicalExpr> = Arc::new(Column::new("geometry", 0));
         let storage_field = WKB_GEOMETRY.to_storage_field("", true).unwrap();
@@ -620,6 +635,43 @@ mod test {
         );
     }
 
+    #[rstest]
+    fn predicate_from_expr_equals_function(#[values("st_equals")] func_name: &str) {
+        let column: Arc<dyn PhysicalExpr> = Arc::new(Column::new("geometry", 0));
+        let storage_field = WKB_GEOMETRY.to_storage_field("", true).unwrap();
+        let literal: Arc<dyn PhysicalExpr> = Arc::new(Literal::new_with_metadata(
+            create_scalar(Some("POLYGON ((0 0, 2 0, 2 2, 0 2, 0 0))"), &WKB_GEOMETRY),
+            Some(storage_field.metadata().into()),
+        ));
+
+        // Test functions that should result in Covers filter
+        let func = create_dummy_spatial_function(func_name, 2);
+        let expr: Arc<dyn PhysicalExpr> = Arc::new(ScalarFunctionExpr::new(
+            func_name,
+            Arc::new(func.clone()),
+            vec![column.clone(), literal.clone()],
+            Arc::new(Field::new("", DataType::Boolean, true)),
+        ));
+        let predicate = SpatialFilter::try_from_expr(&expr).unwrap();
+        assert!(
+            matches!(predicate, SpatialFilter::Covers(_, _)),
+            "Function {func_name} should produce Covers filter"
+        );
+
+        // Test reversed argument order
+        let expr_reversed: Arc<dyn PhysicalExpr> = Arc::new(ScalarFunctionExpr::new(
+            func_name,
+            Arc::new(func),
+            vec![literal.clone(), column.clone()],
+            Arc::new(Field::new("", DataType::Boolean, true)),
+        ));
+        let predicate_reversed = SpatialFilter::try_from_expr(&expr_reversed).unwrap();
+        assert!(
+            matches!(predicate_reversed, SpatialFilter::Covers(_, _)),
+            "Function {func_name} with reversed args should produce Covers filter"
+        );
+    }
+
     #[rstest]
     fn predicate_from_expr_within_covered_by_functions(
         #[values("st_within", "st_covered_by", "st_coveredby")] func_name: &str,