[GitHub] [iceberg] szlta commented on pull request #4662: Core: Metadata table queries fail if a partition column was reused in V2

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szlta commented on PR #4662:
URL: https://github.com/apache/iceberg/pull/4662#issuecomment-1115035033

   Hey @szehon-ho this was just intended to be a quick fix so we don't throw exceptions for the case you mentioned too.
   Currently if we want to collapse the matching partition columns we will hit the following issue:
   
   - suppose we'd have 1000: data, 1001: data, 1002: id in the combined partition type
   - Partitioning.partitionType could collapse this into 1001: data, 1002: id (leaving out the last seen "data" as going back in specs)
   - this will be the "read schema" when reading the manifest files (as the underlying avro files)
   - for spec0, id matching will think that although the file schema has 1000: data, but the read schema doesn't, this reading will just return null for 1001: data and null for 1002: id leaving us no info the collapse upon..
   
   Perhaps if we could rework the re-addition of "data" column to spec so that no new field ID is generated for it? I'm not sure if this will cause other issues though..


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