flyrain commented on code in PR #7105: URL: https://github.com/apache/iceberg/pull/7105#discussion_r1317716670
########## format/partition-statistics-spec.md: ########## @@ -0,0 +1,43 @@ +--- +title: "Partition Statistics Spec" +url: partition-statistics-spec +toc: true +disableSidebar: true +--- +<!-- + - 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. + --> + +# Partition Statistics file format + +This is a specification for partition statistics files. It is designed to store statistics information +for every partition value as a row in the **table default format** sorted based on the `partition`. + +The schema of the file is as follows: + +| Field Id | Field Name | Field Type | isOptional | Doc | +|----------|------------------------------|--------------|------------|-----------------------------------------------------------------------------------------------------------------------------| +| 1 | partition | StructType | false | See [PartitionData](https://github.com/apache/iceberg/blob/master/core/src/main/java/org/apache/iceberg/PartitionData.java) | +| 2 | spec_id | IntegerType | false | Partition spec id | +| 3 | data_record_count | LongType | false | Count of records in data files | +| 4 | data_file_count | IntegerType | false | Count of data files | +| 5 | position_delete_record_count | LongType | true | Count of records in position delete files | +| 6 | position_delete_file_count | IntegerType | true | Count of position delete files | +| 7 | equality_delete_record_count | LongType | true | Count of records in equality delete files | +| 8 | equality_delete_file_count | IntegerType | true | Count of equality delete files | Review Comment: An additional scan on all positional delete files of partition changed are needed. This may still be expensive for sync operations when a write touch a lot of partitions. Admittedly, the precise actual record count is useful. I still think the separated metrics(row count, file size) for data files, delete files are valuable. Users could use these metrics to decide if a compaction is needed, or debug why certain scan is slow. For example, if we see the there are several delete files in a partition, we may compact it for better scan perf. With that, I propose to keep them instead of removing. -- 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]
