vustef commented on code in PR #8715:
URL: https://github.com/apache/arrow-rs/pull/8715#discussion_r2464852865
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parquet/src/arrow/array_reader/mod.rs:
##########
@@ -42,12 +42,13 @@ mod map_array;
mod null_array;
mod primitive_array;
mod row_group_cache;
+mod row_number;
mod struct_array;
#[cfg(test)]
mod test_util;
-// Note that this crate is public under the `experimental` feature flag.
Review Comment:
shouldn't remove this comment
##########
parquet/src/arrow/arrow_reader/mod.rs:
##########
@@ -388,6 +388,8 @@ pub struct ArrowReaderOptions {
/// If encryption is enabled, the file decryption properties can be
provided
#[cfg(feature = "encryption")]
pub(crate) file_decryption_properties:
Option<Arc<FileDecryptionProperties>>,
+
+ virtual_columns: Vec<Field>
Review Comment:
maybe it should be `Vec<&Field>`
##########
parquet/src/arrow/schema/complex.rs:
##########
@@ -541,6 +567,46 @@ impl Visitor {
}
}
+/// Converts a virtual Arrow [`Field`] to a [`ParquetField`]
+///
+/// Virtual fields don't correspond to any data in the parquet file,
+/// but are computed at read time (e.g., row_number)
+///
+/// The levels are computed based on the parent context:
+/// - If nullable: def_level = parent_def_level + 1
+/// - If required: def_level = parent_def_level
+/// - rep_level = parent_rep_level (virtual fields are not repeated)
+fn convert_virtual_field(
Review Comment:
the name used here is not aligned with what other `convert_` functions do
##########
parquet/src/arrow/array_reader/row_number.rs:
##########
@@ -0,0 +1,82 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+use crate::arrow::array_reader::ArrayReader;
+use crate::errors::Result;
+use crate::file::metadata::RowGroupMetaData;
+use arrow_array::{ArrayRef, Int64Array};
+use arrow_schema::DataType;
+use std::any::Any;
+use std::sync::Arc;
+
+pub(crate) struct RowNumberReader {
+ buffered_row_numbers: Vec<i64>,
+ remaining_row_numbers:
std::iter::Flatten<std::vec::IntoIter<std::ops::Range<i64>>>,
+}
+
+impl RowNumberReader {
+ pub(crate) fn try_new<'a>(
+ row_groups: impl Iterator<Item = &'a RowGroupMetaData>,
+ ) -> Result<Self> {
+ let ranges = row_groups
+ .map(|rg| {
+ let first_row_index = rg.first_row_index();
+ Ok(first_row_index..first_row_index + rg.num_rows())
+ })
+ .collect::<Result<Vec<_>>>()?;
+ Ok(Self {
+ buffered_row_numbers: Vec::new(),
+ remaining_row_numbers: ranges.into_iter().flatten(),
+ })
+ }
+}
+
+impl ArrayReader for RowNumberReader {
+ fn read_records(&mut self, batch_size: usize) -> Result<usize> {
+ let starting_len = self.buffered_row_numbers.len();
+ self.buffered_row_numbers
+ .extend((&mut self.remaining_row_numbers).take(batch_size));
+ Ok(self.buffered_row_numbers.len() - starting_len)
+ }
+
+ fn skip_records(&mut self, num_records: usize) -> Result<usize> {
+ // TODO: Use advance_by when it stabilizes to improve performance
Review Comment:
TODO from original PR
##########
parquet/src/arrow/array_reader/builder.rs:
##########
@@ -15,24 +15,25 @@
// specific language governing permissions and limitations
// under the License.
+use arrow_schema::{DataType, Field, Fields, SchemaBuilder};
Review Comment:
shouldn't move this
##########
parquet/src/arrow/async_reader/mod.rs:
##########
@@ -1130,6 +1130,10 @@ impl RowGroups for InMemoryRowGroup<'_> {
}
}
}
+
+ fn row_groups(&self) -> Box<dyn Iterator<Item = &RowGroupMetaData> + '_> {
+ Box::new(std::iter::once(self.metadata.row_group(self.row_group_idx)))
Review Comment:
this duplicates a lot, not sure if anything can be done here
##########
parquet/src/arrow/arrow_reader/mod.rs:
##########
@@ -516,6 +518,22 @@ impl ArrowReaderOptions {
}
}
+ /// Include virtual columns in the output.
+ ///
+ /// Virtual columns are columns that are not part of the Parquet schema,
but are added to the output by the reader.
+ ///
+ /// # Example
+ /// ```
+ /// let virtual_columns = vec![Field::new("row_number",
ArrowDataType::Int64, false).with_extension_type(RowNumber)];
+ /// let options =
ArrowReaderOptions::new().with_virtual_columns(virtual_columns);
+ pub fn with_virtual_columns(self, virtual_columns: Vec<Field>) -> Self {
+ // TODO @vustef: Make sure the passed fields are virtual columns.
Review Comment:
I still have a bunch of TODOs to address
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