[SPARK-25208][SQL] Loosen Cast.forceNullable for DecimalType. #22200
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Test build #95150 has finished for PR 22200 at commit
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LGTM, merging to master! |
asfgit
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## What changes were proposed in this pull request? This is a follow-up pr of #22200. When casting to decimal type, if `Cast.canNullSafeCastToDecimal()`, overflow won't happen, so we don't need to check the result of `Decimal.changePrecision()`. ## How was this patch tested? Existing tests. Closes #22352 from ueshin/issues/SPARK-25208/reduce_code_size. Authored-by: Takuya UESHIN <[email protected]> Signed-off-by: Wenchen Fan <[email protected]> (cherry picked from commit 1b1711e) Signed-off-by: Wenchen Fan <[email protected]>
asfgit
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that referenced
this pull request
Sep 7, 2018
## What changes were proposed in this pull request? This is a follow-up pr of #22200. When casting to decimal type, if `Cast.canNullSafeCastToDecimal()`, overflow won't happen, so we don't need to check the result of `Decimal.changePrecision()`. ## How was this patch tested? Existing tests. Closes #22352 from ueshin/issues/SPARK-25208/reduce_code_size. Authored-by: Takuya UESHIN <[email protected]> Signed-off-by: Wenchen Fan <[email protected]>
cloud-fan
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Nov 12, 2018
| case from: NumericType if to.isWiderThan(from) => true | ||
| case from: DecimalType => | ||
| // truncating or precision lose | ||
| (to.precision - to.scale) > (from.precision - from.scale) |
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In this case, we need rounding, then we need an extra precision to avoid overflow.
E.g., cast 99.95 of Decimal(4, 2) to Decimal(3, 1) will be 100.0, but it’s an overflow and ends up to null. We need Decimal(4, 1) to be null-safe.
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What changes were proposed in this pull request?
Casting to
DecimalTypeis not always needed to force nullable.If the decimal type to cast is wider than original type, or only truncating or precision loss, the casted value won't be
null.How was this patch tested?
Added and modified tests.