[common][flink] Fix missing cast rule for DATE/TIME/TIMESTAMP to bounded CHAR/VARCHAR - #9670
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[common][flink] Fix missing cast rule for DATE/TIME/TIMESTAMP to bounded CHAR/VARCHAR#9670jackylee-ch wants to merge 1 commit into
jackylee-ch wants to merge 1 commit into
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…ded CHAR/VARCHAR DateToStringCastRule, TimeToStringCastRule and TimestampToStringCastRule registered VarCharType.STRING_TYPE as their target, so CastExecutors only matched a type equal to it. A bounded VARCHAR/CHAR target, or a plain STRING NOT NULL, resolved to no rule, and SchemaManagerUtils rejects the column type change when the executor is null even though DataTypeCasts.supportsCast allows it. Key them on DataTypeFamily.CHARACTER_STRING, which the class javadoc here already claims, and trim or pad through BinaryStringUtils like the numeric and boolean rules. Bounded character targets already truncate and blank pad for the other scalar types, asserted since 47d4dd6.
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Purpose
The three date/time-to-string cast rules target
VarCharType.STRING_TYPE, soCastExecutorsonly matches a type equal to it — a boundedVARCHAR(n)/CHAR(n), or a plainSTRING NOT NULL, resolves to no rule.SchemaManagerUtilstreats a null executor as a rejection even thoughDataTypeCasts.supportsCastallows the change, soALTER TABLE T MODIFY (b VARCHAR(10))on aTIMESTAMP(3)column fails with "cannot be converted to VARCHAR(10) without losing information", while the same statement on anINTcolumn works.Keyed on
DataTypeFamily.CHARACTER_STRINGnow, which the class javadoc of all three already claims, trimming and padding throughBinaryStringUtilslike the numeric and boolean rules. Truncating to a bounded target and blank paddingCHARis existing asserted behaviour for the other scalars (testModifyColumnTypeFromNumericToString, 47d4dd6). This also unblocks Spark'sCAST(<datetime> AS VARCHAR(n))pushdown throughCastTransform, with the truncating semanticsINTalready has.Tests
DateTimeToCharacterStringCastRuleTest, andSchemaChangeITCase.testModifyColumnTypeFromTimestampToBoundedString, which fails on master with the exception above.Written with Claude Code; reasoning and verification are mine.