parquet/arrow/array_reader/
null_array.rs

1// Licensed to the Apache Software Foundation (ASF) under one
2// or more contributor license agreements.  See the NOTICE file
3// distributed with this work for additional information
4// regarding copyright ownership.  The ASF licenses this file
5// to you under the Apache License, Version 2.0 (the
6// "License"); you may not use this file except in compliance
7// with the License.  You may obtain a copy of the License at
8//
9//   http://www.apache.org/licenses/LICENSE-2.0
10//
11// Unless required by applicable law or agreed to in writing,
12// software distributed under the License is distributed on an
13// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
14// KIND, either express or implied.  See the License for the
15// specific language governing permissions and limitations
16// under the License.
17
18use crate::arrow::array_reader::{read_records, skip_records, ArrayReader};
19use crate::arrow::record_reader::RecordReader;
20use crate::column::page::PageIterator;
21use crate::data_type::DataType;
22use crate::errors::Result;
23use crate::schema::types::ColumnDescPtr;
24use arrow_array::ArrayRef;
25use arrow_buffer::ArrowNativeType;
26use arrow_schema::DataType as ArrowType;
27use std::any::Any;
28use std::sync::Arc;
29
30/// A NullArrayReader reads Parquet columns stored as null int32s with an Arrow
31/// NullArray type.
32pub struct NullArrayReader<T>
33where
34    T: DataType,
35    T::T: ArrowNativeType,
36{
37    data_type: ArrowType,
38    pages: Box<dyn PageIterator>,
39    def_levels_buffer: Option<Vec<i16>>,
40    rep_levels_buffer: Option<Vec<i16>>,
41    record_reader: RecordReader<T>,
42}
43
44impl<T> NullArrayReader<T>
45where
46    T: DataType,
47    T::T: ArrowNativeType,
48{
49    /// Construct null array reader.
50    pub fn new(pages: Box<dyn PageIterator>, column_desc: ColumnDescPtr) -> Result<Self> {
51        let record_reader = RecordReader::<T>::new(column_desc);
52
53        Ok(Self {
54            data_type: ArrowType::Null,
55            pages,
56            def_levels_buffer: None,
57            rep_levels_buffer: None,
58            record_reader,
59        })
60    }
61}
62
63/// Implementation of primitive array reader.
64impl<T> ArrayReader for NullArrayReader<T>
65where
66    T: DataType,
67    T::T: ArrowNativeType,
68{
69    fn as_any(&self) -> &dyn Any {
70        self
71    }
72
73    /// Returns data type of primitive array.
74    fn get_data_type(&self) -> &ArrowType {
75        &self.data_type
76    }
77
78    fn read_records(&mut self, batch_size: usize) -> Result<usize> {
79        read_records(&mut self.record_reader, self.pages.as_mut(), batch_size)
80    }
81
82    fn consume_batch(&mut self) -> Result<ArrayRef> {
83        // convert to arrays
84        let array = arrow_array::NullArray::new(self.record_reader.num_values());
85
86        // save definition and repetition buffers
87        self.def_levels_buffer = self.record_reader.consume_def_levels();
88        self.rep_levels_buffer = self.record_reader.consume_rep_levels();
89
90        // Must consume bitmap buffer
91        self.record_reader.consume_bitmap_buffer();
92
93        self.record_reader.reset();
94        Ok(Arc::new(array))
95    }
96
97    fn skip_records(&mut self, num_records: usize) -> Result<usize> {
98        skip_records(&mut self.record_reader, self.pages.as_mut(), num_records)
99    }
100
101    fn get_def_levels(&self) -> Option<&[i16]> {
102        self.def_levels_buffer.as_deref()
103    }
104
105    fn get_rep_levels(&self) -> Option<&[i16]> {
106        self.rep_levels_buffer.as_deref()
107    }
108}
parquet/arrow/array_reader/null_array.rs

parquet/arrow/array_reader/
null_array.rs
