[WIP][SPARK-57832][SQL] Support timestamp - timestamp subtraction for nanosecond-precision timestamps - #57680
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…second-precision timestamps ### What changes were proposed in this pull request? `SubtractTimestamps` (the `timestamp - timestamp` operator) previously only accepted the microsecond timestamp types (`AnyTimestampType`). This PR extends it to also accept the nanosecond-precision timestamp types (`TIMESTAMP_NTZ(p)` / `TIMESTAMP_LTZ(p)`, `p` in [7, 9]). The difference is always reported on the microsecond grid, since the result is a `DayTimeIntervalType` (which has microsecond resolution). Each operand therefore contributes only its `epochMicros`; the sub-microsecond remainder is truncated. This keeps `ts_nanos - ts_nanos` numerically identical to `ts_nanos::timestamp - ts_nanos::timestamp`. Concretely: - `SubtractTimestamps.inputTypes` widens to `TypeCollection(AnyTimestampType, AnyTimestampNanoType)` for both operands, and `nullSafeEval` / `doGenCode` reduce a `TimestampNanosVal` operand to its `epochMicros` before subtracting. - `BinaryArithmeticWithDatetimeResolver` recognizes a nanos operand on either side of a `Subtract` and routes it to `SubtractTimestamps`. - The `DateTimeOperations` / `AnsiDateTimeOperations` type-coercion rules unify mixed operands (DATE vs timestamp, or two timestamps differing in precision or time-zone family). A cross-family pair unifies in the NTZ family (mirroring the microsecond `TIMESTAMP - TIMESTAMP_NTZ` precedent); a same-family pair keeps its family so an LTZ pair still subtracts in the session time zone. For pure-microsecond inputs the behavior is unchanged. ### Why are the changes needed? Sub-task of SPARK-56822 (nanosecond-precision timestamp support). Without this, subtracting two nanosecond timestamps fails analysis. ### Does this PR introduce _any_ user-facing change? Yes. `timestamp_nanos - timestamp_nanos` (and mixed micro/nanos, and nanos/DATE) now produces a microsecond-grid `DayTimeIntervalType` instead of failing analysis. ### How was this patch tested? - New unit test in `DateExpressionsSuite` covering NTZ/LTZ nanos operands, sub-microsecond truncation, pre-epoch values, NULLs, and interpreted/codegen consistency. - New coercion cases in `TypeCoercionSuite` / `AnsiTypeCoercionSuite`. - New golden SQL cases in `timestamp-ntz-nanos.sql` / `timestamp-ltz-nanos.sql`. Co-authored-by: Isaac
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What changes were proposed in this pull request?
SubtractTimestamps(thetimestamp - timestampoperator) previously only accepted the microsecond timestamp types (AnyTimestampType). This PR extends it to also accept the nanosecond-precision timestamp types (TIMESTAMP_NTZ(p)/TIMESTAMP_LTZ(p),pin [7, 9]).The difference is always reported on the microsecond grid, since the result is a
DayTimeIntervalType(which has microsecond resolution). Each operand therefore contributes only itsepochMicros; the sub-microsecond remainder is truncated. This keepsts_nanos - ts_nanosnumerically identical tots_nanos::timestamp - ts_nanos::timestamp.Concretely:
SubtractTimestamps.inputTypeswidens toTypeCollection(AnyTimestampType, AnyTimestampNanoType)for both operands, andnullSafeEval/doGenCodereduce aTimestampNanosValoperand to itsepochMicrosbefore subtracting.BinaryArithmeticWithDatetimeResolverrecognizes a nanos operand on either side of aSubtractand routes it toSubtractTimestamps.DateTimeOperations/AnsiDateTimeOperationstype-coercion rules unify mixed operands (DATE vs timestamp, or two timestamps differing in precision or time-zone family). A cross-family pair unifies in the NTZ family (mirroring the microsecondTIMESTAMP - TIMESTAMP_NTZprecedent); a same-family pair keeps its family so an LTZ pair still subtracts in the session time zone.For pure-microsecond inputs the behavior is unchanged.
Why are the changes needed?
Sub-task of SPARK-56822 (nanosecond-precision timestamp support). Without this, subtracting two nanosecond timestamps fails analysis.
Does this PR introduce any user-facing change?
Yes.
timestamp_nanos - timestamp_nanos(and mixed micro/nanos, and nanos/DATE) now produces a microsecond-gridDayTimeIntervalTypeinstead of failing analysis.How was this patch tested?
DateExpressionsSuitecovering NTZ/LTZ nanos operands, sub-microsecond truncation, pre-epoch values, NULLs, and interpreted/codegen consistency.TypeCoercionSuite/AnsiTypeCoercionSuite.timestamp-ntz-nanos.sql/timestamp-ltz-nanos.sql.Was this patch authored or co-authored using generative AI tooling?
Generated-by: Claude Code (Claude Opus 4.8)