Coerce BinaryView/Utf8View to LargeBinary/LargeUtf8 on output. #12271
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Sep 6, 2024
| let if_not_coerced = "Projection: a\n Sort: a ASC NULLS FIRST\n Projection: a\n EmptyRelation"; | ||
| do_not_coerce_on_output(plan.clone(), if_not_coerced)?; | ||
| // Plan B: coerce requested: Utf8View => LargeUtf8 only on outermost | ||
| let if_coerced = "Projection: CAST(a AS LargeUtf8)\n Sort: a ASC NULLS FIRST\n Projection: a\n EmptyRelation"; |
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Which issue does this PR close?
Closes #12119
Rationale for this change
We plan to change Datafusion to use BinaryVIew and Utf8View by default, however, the rest of the arrow ecosystem may not be ready for these data types. As such, we want to provide the option to cast the query output to a non-view type.
Because either Utf8 or LargeUtf8 can represented as a Utf8View, the cast on output converts to the larger type. Same with BinaryView to LargeBinary.
What changes are included in this PR?
During type coercion, after the plan has been coerced -- then based upon the final output type determine if an additional cast is needed.
Are these changes tested?
Yes.
Are there any user-facing changes?
Yes.
I made one existing API public (no longer crate private), and we added the optimizer config option
expand_views_at_output.