[SPARK-48439][SQL] Derby: Calculate suitable precision and scale for DECIMAL type #46776
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cc @dongjoon-hyun @cloud-fan thanks |
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Merged into master for Spark 4.0. Thanks @yaooqinn |
LuciferYang
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What changes were proposed in this pull request?
When storing
decimal(p, s)to derby, ifp > 31,sis wrongly hardcoded to5which is the assumed default scale of derby decimal. Actually, 0 is the default scale, 5 is the default precision https://db.apache.org/derby/docs/10.13/ref/rrefsqlj15260.htmlThis PR calculates a suitable scale to make room for precision.
Why are the changes needed?
avoid precision loss
Does this PR introduce any user-facing change?
Yes, but derby is rare in production environments, and the new mapping are compatible for most usecases
How was this patch tested?
new tests
Was this patch authored or co-authored using generative AI tooling?
no