Field pruning in nested struct scan#7327
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brancz wants to merge 2 commits intovortex-data:developfrom
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connortsui20
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Apr 7, 2026
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| let can_fast_path = match target_fields { | ||
| None => true, | ||
| Some(fields) => fields.len() >= n_struct_fields, | ||
| }; | ||
| if can_fast_path { |
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Summary
I'm trying to have scans read only a subset of a nested struct. It's of the shape:
List<Struct<a: Utf8, b: Int64>, so I can't use regular projections in DataFusion, since those only support indices. This is my best attempt, combined with an optimizer rule that modifies the table schema to the subset under certain circumstances.Testing
Added a unit test that fails without the second commit.
Notes
Happy to think through other approaches to this, this was just the first thing that I came up with.