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Posted to issues@iceberg.apache.org by "ajantha-bhat (via GitHub)" <gi...@apache.org> on 2023/03/15 05:39:58 UTC

[GitHub] [iceberg] ajantha-bhat commented on a diff in pull request #7105: Spec: Add partition stats spec

ajantha-bhat commented on code in PR #7105:
URL: https://github.com/apache/iceberg/pull/7105#discussion_r1136556742


##########
format/partition-statistics-spec.md:
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@@ -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
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+ - The ASF licenses this file to You under the Apache License, Version 2.0
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+ -   http://www.apache.org/licenses/LICENSE-2.0
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+ - WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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+ -->
+
+# 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                                                                                                         |

Review Comment:
   There was also an ask for the `latest sequence number` per partition, the `last modified time` per partition along with `file size`. 
   Also, I remember some ask for lower bounds and upper bounds for other columns per partition. 
   
   These are not must-haves (but good to have). So, the plan is to brainstorm on these in phase 2 implementation as mentioned in the design doc/iceberg sync. 
   
   >  SELECT sum(file_size_in_bytes) FROM db.table.files GROUP By partition
   
   the plan is to incrementally compute these per snapshot. But yeah, manifest's data file entry already has this and we just need to sum this. Let us discuss more on this in phase 2.  



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