Metadata.Partitions physical / logical column names?

[shanisolomon]

For Delta Log tables with column mapping enabled, should partition columns in the metadata action be referenced by their physical names or logical names?

For example, if the partition column has the logical name date but its physical name is col-abc123, should the metadata action look like:

{
  "metaData": {
    "partitionColumns": ["date"]
  }
}

or:

{
  "metaData": {
    "partitionColumns": ["col-abc123"]
  }
}

I read the protocol as implying the physical name, but wanted to confirm the expected behavior.

[shanisolomon]

@larsk-db perhaps you can weigh in here please? Thanks!

[larsk-db]

metaData.partitionColumns should contain logical names, e.g. "date" in your example. Only the per action entries (e.g. add.partitionValues) should contain the physical names. This way partition columns can be renamed a the logical level (updating metaData.partitionColumns) while leaving the per-file entries unchanged with the physical names that the parquet files actually have.