docs: clarify output schema handling for extension relations#1018
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benbellick merged 1 commit intomainfrom May 6, 2026
Merged
docs: clarify output schema handling for extension relations#1018benbellick merged 1 commit intomainfrom
benbellick merged 1 commit intomainfrom
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benbellick
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With 2 votes (including myself) I am going to go ahead and merge this one. Thanks! |
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For standard relations, a consumer can derive the output schema from the relation definition (e.g., Project appends expression columns to the input schema). For extension relations, this is clearly impossible. I thought it would be nice to explicitly document that this needs to be handled by the extension authors.
The motivating example here is a custom
Unnestoperator we have (via anExtensionSingleRel). There is nothing in core substrait enforcing whether the unnested column is appended to the schema or something else.Note: This PR was developed with AI assistance. All changes have been reviewed, and I take full responsibility for this contribution.
This change is