[jira] [Created] (SPARK-57811) Support string to nanosecond-precision timestamp coercion in comparisons and predicates

["Max Gekk (Jira)" <ji...@apache.org>]

Max Gekk created SPARK-57811:
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             Summary: Support string to nanosecond-precision timestamp coercion in comparisons and predicates
                 Key: SPARK-57811
                 URL: https://issues.apache.org/jira/browse/SPARK-57811
             Project: Spark
          Issue Type: Sub-task
          Components: SQL
    Affects Versions: 4.3.0
            Reporter: Max Gekk


This sub-task is part of the umbrella SPARK-56822 (timestamps with nanosecond precision).

h2. Problem
{{findCommonTypeForBinaryComparison}} (analysis/TypeCoercion.scala ~L144-147) special-cases only {{TimestampType + StringType}}, and {{StringPromotionTypeCoercion}} (~L58-61) matches only the microsecond {{TimestampTypeExpression}} (DataTypeExpression.scala ~L45). A string operand compared to a nanosecond timestamp column is therefore not coerced like the microsecond case: non-ANSI may promote the timestamp to string, ANSI may fail. Column-vs-column nanos/micro is already correct (SPARK-57454); this is the string-literal path only.

h2. Goal
Coerce a string operand compared to a nanosecond timestamp column to the nanosecond type (parity with microsecond), in both the binary-comparison common-type path and the equality string-promotion path, for ANSI and non-ANSI.

h2. Scope
Extend {{findCommonTypeForBinaryComparison}} and {{StringPromotionTypeCoercion}} (and the {{DataTypeExpression}} matchers) to include {{AnyTimestampNanoType}}.

h2. Acceptance criteria
* {{ts_nanos = '2020-01-02 03:04:05.123456789'}} and range predicates resolve by casting the string to the nanosecond type; results correct in both ANSI and non-ANSI modes.

h2. Testing
{{TypeCoercionSuite}} / {{AnsiTypeCoercionSuite}}; nanos golden files.

h2. Dependencies
None - independent (widening resolved in SPARK-57454). Feeds the cross-precision test-coverage sub-task.




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