[GitHub] [arrow] yordan-pavlov commented on a change in pull request #8630: ARROW-10540 [Rust] Improve filtering

[GitBox <gi...@apache.org>]

yordan-pavlov commented on a change in pull request #8630:
URL: https://github.com/apache/arrow/pull/8630#discussion_r520890613



##########
File path: rust/arrow/benches/filter_kernels.rs
##########
@@ -14,137 +14,136 @@
 // KIND, either express or implied.  See the License for the
 // specific language governing permissions and limitations
 // under the License.
+extern crate arrow;
+
+use rand::{
+    distributions::{Alphanumeric, Standard},
+    prelude::Distribution,
+    Rng,
+};
 
 use arrow::array::*;
-use arrow::compute::{filter, FilterContext};
+use arrow::compute::{build_filter, filter};
 use arrow::datatypes::ArrowNumericType;
+use arrow::datatypes::{Float32Type, UInt8Type};
+
 use criterion::{criterion_group, criterion_main, Criterion};
 
-fn create_primitive_array<T, F>(size: usize, value_fn: F) -> PrimitiveArray<T>
+fn create_primitive_array<T>(size: usize, null_density: f32) -> PrimitiveArray<T>
 where
     T: ArrowNumericType,
-    F: Fn(usize) -> T::Native,
+    Standard: Distribution<T::Native>,
 {
+    // use random numbers to avoid spurious compiler optimizations wrt to branching
+    let mut rng = rand::thread_rng();
     let mut builder = PrimitiveArray::<T>::builder(size);
-    for i in 0..size {
-        builder.append_value(value_fn(i)).unwrap();
+
+    for _ in 0..size {
+        if rng.gen::<f32>() < null_density {
+            builder.append_null().unwrap();
+        } else {
+            builder.append_value(rng.gen()).unwrap();
+        }
     }
     builder.finish()
 }
 
-fn create_u8_array_with_nulls(size: usize) -> UInt8Array {
-    let mut builder = UInt8Builder::new(size);
-    for i in 0..size {
-        if i % 2 == 0 {
-            builder.append_value(1).unwrap();
-        } else {
+fn create_string_array(size: usize, null_density: f32) -> StringArray {
+    // use random numbers to avoid spurious compiler optimizations wrt to branching
+    let mut rng = rand::thread_rng();
+    let mut builder = StringBuilder::new(size);
+
+    for _ in 0..size {
+        if rng.gen::<f32>() < null_density {
             builder.append_null().unwrap();
+        } else {
+            let value = rng.sample_iter(&Alphanumeric).take(10).collect::<String>();
+            builder.append_value(&value).unwrap();
         }
     }
     builder.finish()
 }
 
-fn create_bool_array<F>(size: usize, value_fn: F) -> BooleanArray
-where
-    F: Fn(usize) -> bool,
-{
+fn create_bool_array(size: usize, trues_density: f32) -> BooleanArray {
+    let mut rng = rand::thread_rng();
     let mut builder = BooleanBuilder::new(size);
-    for i in 0..size {
-        builder.append_value(value_fn(i)).unwrap();
+    for _ in 0..size {
+        let value = rng.gen::<f32>() < trues_density;

Review comment:
       using random numbers to generate the filter arrays makes it difficult to control filter selectivity; also doesn't that make each benchmark run unique which I think is the opposite of what we want - we want consistent benchmarks with stable, repeatable conditions




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