[GitHub] [arrow-rs] tustvold commented on a change in pull request #1248: Specialized filter kernels

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

tustvold commented on a change in pull request #1248:
URL: https://github.com/apache/arrow-rs/pull/1248#discussion_r798378622



##########
File path: arrow/src/compute/kernels/filter.rs
##########
@@ -185,68 +267,573 @@ pub fn prep_null_mask_filter(filter: &BooleanArray) -> BooleanArray {
 /// # Ok(())
 /// # }
 /// ```
-pub fn filter(array: &dyn Array, predicate: &BooleanArray) -> Result<ArrayRef> {
-    if predicate.null_count() > 0 {
-        // this greatly simplifies subsequent filtering code
-        // now we only have a boolean mask to deal with
-        let predicate = prep_null_mask_filter(predicate);
-        return filter(array, &predicate);
+pub fn filter(values: &dyn Array, predicate: &BooleanArray) -> Result<ArrayRef> {
+    let predicate = FilterBuilder::new(predicate).build();
+    filter_array(values, &predicate)
+}
+
+/// Returns a new [RecordBatch] with arrays containing only values matching the filter.
+pub fn filter_record_batch(
+    record_batch: &RecordBatch,
+    predicate: &BooleanArray,
+) -> Result<RecordBatch> {
+    let filter = FilterBuilder::new(predicate).optimize().build();
+
+    let filtered_arrays = record_batch
+        .columns()
+        .iter()
+        .map(|a| filter_array(a, &filter))
+        .collect::<Result<Vec<_>>>()?;
+
+    RecordBatch::try_new(record_batch.schema(), filtered_arrays)
+}
+
+/// A builder to construct [`FilterPredicate`]
+#[derive(Debug)]
+pub struct FilterBuilder {

Review comment:
       The idea behind this is that we may wish to give the user more control over how the predicate is executed, by creating a builder we have an obvious extension point for doing this




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