Introduce ReadPlan to encapsulate the calculation of what rows to decode

Author: alamb

parquet/src/arrow/arrow_reader/mod.rs

@@ -21,10 +21,8 @@ use arrow_array::cast::AsArray;
 use arrow_array::Array;
 use arrow_array::{RecordBatch, RecordBatchReader};
 use arrow_schema::{ArrowError, DataType as ArrowType, Schema, SchemaRef};
-use arrow_select::filter::prep_null_mask_filter;
 pub use filter::{ArrowPredicate, ArrowPredicateFn, RowFilter};
 pub use selection::{RowSelection, RowSelector};
-use std::collections::VecDeque;
 use std::sync::Arc;
 
 pub use crate::arrow::array_reader::RowGroups;
@@ -39,7 +37,10 @@ use crate::file::metadata::{ParquetMetaData, ParquetMetaDataReader};
 use crate::file::reader::{ChunkReader, SerializedPageReader};
 use crate::schema::types::SchemaDescriptor;
 
+use read_plan::{ReadPlan, ReadPlanBuilder};
+
 mod filter;
+pub(crate) mod read_plan;
 mod selection;
 pub mod statistics;
 
@@ -679,38 +680,33 @@ impl<T: ChunkReader + 'static> ParquetRecordBatchReaderBuilder<T> {
         };
 
         let mut filter = self.filter;
-        let mut selection = self.selection;
+        let mut plan_builder = ReadPlanBuilder::new(batch_size).with_selection(self.selection);
 
+        // Update selection based on any filters
         if let Some(filter) = filter.as_mut() {
             for predicate in filter.predicates.iter_mut() {
-                if !selects_any(selection.as_ref()) {
+                // break early if we have already ruled out all rows
+                if !plan_builder.selects_any() {
                     break;
                 }
 
+                // TODO move this into the read_plan
                 let array_reader =
                     build_array_reader(self.fields.as_deref(), predicate.projection(), &reader)?;
 
-                selection = Some(evaluate_predicate(
-                    batch_size,
-                    array_reader,
-                    selection,
-                    predicate.as_mut(),
-                )?);
+                plan_builder = plan_builder.with_predicate(array_reader, predicate.as_mut())?;
             }
         }
 
         let array_reader = build_array_reader(self.fields.as_deref(), &self.projection, &reader)?;
+        let read_plan = plan_builder
+            .limited(reader.num_rows())
+            .with_offset(self.offset)
+            .with_limit(self.limit)
+            .build_limited()
+            .build();
 
-        // If selection is empty, truncate
-        if !selects_any(selection.as_ref()) {
-            selection = Some(RowSelection::from(vec![]));
-        }
-
-        Ok(ParquetRecordBatchReader::new(
-            batch_size,
-            array_reader,
-            apply_range(selection, reader.num_rows(), self.offset, self.limit),
-        ))
+        Ok(ParquetRecordBatchReader::new(array_reader, read_plan))
     }
 }
 
@@ -789,11 +785,9 @@ impl<T: ChunkReader + 'static> PageIterator for ReaderPageIterator<T> {}
 /// An `Iterator<Item = ArrowResult<RecordBatch>>` that yields [`RecordBatch`]
 /// read from a parquet data source
 pub struct ParquetRecordBatchReader {
-    batch_size: usize,
     array_reader: Box<dyn ArrayReader>,
     schema: SchemaRef,
-    /// Row ranges to be selected from the data source
-    selection: Option<VecDeque<RowSelector>>,
+    read_plan: ReadPlan,
 }
 
 impl Iterator for ParquetRecordBatchReader {
@@ -814,9 +808,10 @@ impl ParquetRecordBatchReader {
     /// simplify error handling with `?`
     fn next_inner(&mut self) -> Result<Option<RecordBatch>> {
         let mut read_records = 0;
-        match self.selection.as_mut() {
+        let batch_size = self.batch_size();
+        match self.read_plan.selection_mut() {
             Some(selection) => {
-                while read_records < self.batch_size && !selection.is_empty() {
+                while read_records < batch_size && !selection.is_empty() {
                     let front = selection.pop_front().unwrap();
                     if front.skip {
                         let skipped = self.array_reader.skip_records(front.row_count)?;
@@ -838,7 +833,7 @@ impl ParquetRecordBatchReader {
                     }
 
                     // try to read record
-                    let need_read = self.batch_size - read_records;
+                    let need_read = batch_size - read_records;
                     let to_read = match front.row_count.checked_sub(need_read) {
                         Some(remaining) if remaining != 0 => {
                             // if page row count less than batch_size we must set batch size to page row count.
@@ -855,7 +850,7 @@ impl ParquetRecordBatchReader {
                 }
             }
             None => {
-                self.array_reader.read_records(self.batch_size)?;
+                self.array_reader.read_records(self.batch_size())?;
             }
         };
 
@@ -905,116 +900,37 @@ impl ParquetRecordBatchReader {
         let array_reader =
             build_array_reader(levels.levels.as_ref(), &ProjectionMask::all(), row_groups)?;
 
+        let read_plan = ReadPlanBuilder::new(batch_size)
+            .with_selection(selection)
+            .build();
+
         Ok(Self {
-            batch_size,
             array_reader,
             schema: Arc::new(Schema::new(levels.fields.clone())),
-            selection: selection.map(|s| s.trim().into()),
+            read_plan,
         })
     }
 
     /// Create a new [`ParquetRecordBatchReader`] that will read at most `batch_size` rows at
     /// a time from [`ArrayReader`] based on the configured `selection`. If `selection` is `None`
     /// all rows will be returned
-    pub(crate) fn new(
-        batch_size: usize,
-        array_reader: Box<dyn ArrayReader>,
-        selection: Option<RowSelection>,
-    ) -> Self {
+    pub(crate) fn new(array_reader: Box<dyn ArrayReader>, read_plan: ReadPlan) -> Self {
         let schema = match array_reader.get_data_type() {
             ArrowType::Struct(ref fields) => Schema::new(fields.clone()),
             _ => unreachable!("Struct array reader's data type is not struct!"),
         };
 
         Self {
-            batch_size,
             array_reader,
             schema: Arc::new(schema),
-            selection: selection.map(|s| s.trim().into()),
+            read_plan,
         }
     }
-}
 
-/// Returns `true` if `selection` is `None` or selects some rows
-pub(crate) fn selects_any(selection: Option<&RowSelection>) -> bool {
-    selection.map(|x| x.selects_any()).unwrap_or(true)
-}
-
-/// Applies an optional offset and limit to an optional [`RowSelection`]
-pub(crate) fn apply_range(
-    mut selection: Option<RowSelection>,
-    row_count: usize,
-    offset: Option<usize>,
-    limit: Option<usize>,
-) -> Option<RowSelection> {
-    // If an offset is defined, apply it to the `selection`
-    if let Some(offset) = offset {
-        selection = Some(match row_count.checked_sub(offset) {
-            None => RowSelection::from(vec![]),
-            Some(remaining) => selection
-                .map(|selection| selection.offset(offset))
-                .unwrap_or_else(|| {
-                    RowSelection::from(vec![
-                        RowSelector::skip(offset),
-                        RowSelector::select(remaining),
-                    ])
-                }),
-        });
-    }
-
-    // If a limit is defined, apply it to the final `selection`
-    if let Some(limit) = limit {
-        selection = Some(
-            selection
-                .map(|selection| selection.limit(limit))
-                .unwrap_or_else(|| {
-                    RowSelection::from(vec![RowSelector::select(limit.min(row_count))])
-                }),
-        );
-    }
-    selection
-}
-
-/// Evaluates an [`ArrowPredicate`], returning a [`RowSelection`] indicating
-/// which rows to return.
-///
-/// `input_selection`: Optional pre-existing selection. If `Some`, then the
-/// final [`RowSelection`] will be the conjunction of it and the rows selected
-/// by `predicate`.
-///
-/// Note: A pre-existing selection may come from evaluating a previous predicate
-/// or if the [`ParquetRecordBatchReader`] specified an explicit
-/// [`RowSelection`] in addition to one or more predicates.
-pub(crate) fn evaluate_predicate(
-    batch_size: usize,
-    array_reader: Box<dyn ArrayReader>,
-    input_selection: Option<RowSelection>,
-    predicate: &mut dyn ArrowPredicate,
-) -> Result<RowSelection> {
-    let reader = ParquetRecordBatchReader::new(batch_size, array_reader, input_selection.clone());
-    let mut filters = vec![];
-    for maybe_batch in reader {
-        let maybe_batch = maybe_batch?;
-        let input_rows = maybe_batch.num_rows();
-        let filter = predicate.evaluate(maybe_batch)?;
-        // Since user supplied predicate, check error here to catch bugs quickly
-        if filter.len() != input_rows {
-            return Err(arrow_err!(
-                "ArrowPredicate predicate returned {} rows, expected {input_rows}",
-                filter.len()
-            ));
-        }
-        match filter.null_count() {
-            0 => filters.push(filter),
-            _ => filters.push(prep_null_mask_filter(&filter)),
-        };
+    #[inline(always)]
+    pub(crate) fn batch_size(&self) -> usize {
+        self.read_plan.batch_size()
     }
-
-    let raw = RowSelection::from_filters(&filters);
-    Ok(match input_selection {
-        Some(selection) => selection.and_then(&raw),
-        None => raw,
-    })
 }
 
 #[cfg(test)]
@@ -3993,7 +3909,7 @@ mod tests {
             .build()
             .unwrap();
         assert_ne!(1024, num_rows);
-        assert_eq!(reader.batch_size, num_rows as usize);
+        assert_eq!(reader.read_plan.batch_size(), num_rows as usize);
     }
 
     #[test]