wgtmac commented on code in PR #63: URL: https://github.com/apache/parquet-testing/pull/63#discussion_r1849584329
########## data/map_no_value.md: ########## @@ -0,0 +1,159 @@ +<!-- + ~ 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. + --> + +`map_no_value.parquet` is generated with parquet-rs version 53.2.0 +using the following code: +``` + fn main() { + use crate::schema::parser::parse_message_type; + use crate::file::writer::SerializedFileWriter; + use crate::data_type::Int32Type; + use std::sync::Arc; + + let schema = " + message spark_schema { + REQUIRED group my_map (MAP) { + REPEATED group key_value { + REQUIRED INT32 key; + OPTIONAL INT32 value; + } + } + REQUIRED group my_map_no_v (MAP) { + REPEATED group key_value { + REQUIRED INT32 key; + } + } + REQUIRED group my_list (LIST) { + REPEATED group list { + REQUIRED INT32 element; + } + } + } + "; + let schema = Arc::new(parse_message_type(schema).unwrap()); + + // Write Parquet file to buffer + let mut buffer = std::fs::File::create("/tmp/map_no_value.parquet").unwrap(); + let mut file_writer = + SerializedFileWriter::new(&mut buffer, schema, Default::default()).unwrap(); + let mut row_group_writer = file_writer.next_row_group().unwrap(); + + // Write column my_map.key_value.key + let mut column_writer = row_group_writer.next_column().unwrap().unwrap(); + column_writer + .typed::<Int32Type>() + .write_batch( + &[1, 2, 3, 4, 5, 6, 7, 8, 9], + Some(&[1, 1, 1, 1, 1, 1, 1, 1, 1]), + Some(&[0, 1, 1, 0, 1, 1, 0, 1, 1]), + ) + .unwrap(); + column_writer.close().unwrap(); + + // Write column my_map.key_value.value + let mut column_writer = row_group_writer.next_column().unwrap().unwrap(); + column_writer + .typed::<Int32Type>() + .write_batch( + &[], + Some(&[1, 1, 1, 1, 1, 1, 1, 1, 1]), + Some(&[0, 1, 1, 0, 1, 1, 0, 1, 1]), + ) + .unwrap(); + column_writer.close().unwrap(); + + // Write column my_map_no_v.key_value.key + let mut column_writer = row_group_writer.next_column().unwrap().unwrap(); + column_writer + .typed::<Int32Type>() + .write_batch( + &[1, 2, 3, 4, 5, 6, 7, 8, 9], + Some(&[1, 1, 1, 1, 1, 1, 1, 1, 1]), + Some(&[0, 1, 1, 0, 1, 1, 0, 1, 1]), + ) + .unwrap(); + column_writer.close().unwrap(); + + // Write column my_list.list.element + let mut column_writer = row_group_writer.next_column().unwrap().unwrap(); + column_writer + .typed::<Int32Type>() + .write_batch( + &[1, 2, 3, 4, 5, 6, 7, 8, 9], + Some(&[1, 1, 1, 1, 1, 1, 1, 1, 1]), + Some(&[0, 1, 1, 0, 1, 1, 0, 1, 1]), + ) + .unwrap(); + column_writer.close().unwrap(); + + // Finalize Parquet file + row_group_writer.close().unwrap(); + file_writer.close().unwrap(); + } +``` + +It contains a MAP with all null values, a second MAP without a `values` field, and +an equivalent LIST repeating the MAP keys. The first column is 3 MAP rows: +``` +{1 -> null, 2 -> null, 3 -> null} +{4 -> null, 5 -> null, 6 -> null} +{7 -> null, 8 -> null, 9 -> null} +``` + +The last two columns comprise 3 equivalent rows of `list<Integer>`: +``` +[1, 2, 3] +[4, 5, 6] +[7, 8, 9] +``` + +Here is the file metadata printed by parquet-cli: +``` +File path: map_no_value.parquet +Created by: parquet-rs version 53.2.0 +Properties: (none) +Schema: +message spark_schema { + required group my_map (MAP) { + repeated group key_value { + required int32 key; + optional int32 value; + } + } + required group my_map_no_v (MAP) { + repeated group key_value { + required int32 key; + } + } + required group my_list (LIST) { + repeated group list { + required int32 element; + } + } +} + + +Row group 0: count: 3 123.00 B records start: 4 total(compressed): 369 B total(uncompressed):369 B Review Comment: The row group is 369 B but the total file size is 1.1KB. Can we reduce those unnecessary overhead? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
