JingsongLi commented on a change in pull request #8730:
[FLINK-12834][table-planner-blink] Support CharType and BinaryType
URL: https://github.com/apache/flink/pull/8730#discussion_r294602280
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File path:
flink-table/flink-table-planner-blink/src/main/scala/org/apache/flink/table/calcite/FlinkTypeFactory.scala
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@@ -379,14 +380,25 @@ object FlinkTypeFactory {
case BIGINT => new BigIntType()
case FLOAT => new FloatType()
case DOUBLE => new DoubleType()
- case VARCHAR | CHAR =>
- // TODO we use VarCharType to support sql CHAR, VarCharType don't
support 0 length
- new VarCharType(
- if (relDataType.getPrecision == 0) VarCharType.MAX_LENGTH else
relDataType.getPrecision)
- case VARBINARY | BINARY =>
- // TODO we use VarBinaryType to support sql BINARY, VarBinaryType
don't support 0 length
- new VarBinaryType(
- if (relDataType.getPrecision == 0) VarBinaryType.MAX_LENGTH else
relDataType.getPrecision)
+ case CHAR =>
+ if (relDataType.getPrecision == 0) {
+ CharType.ofEmptyLiteral
+ } else {
+ new CharType(relDataType.getPrecision)
+ }
+ case VARCHAR =>
+ // Calcite will return a varchar RelDataType with precision 0, for
example,
+ // SUBSTR('', 2, -1), Calcite infers that the return value must not
exist
+ // (in this case, null will be returned when executed in Blink runner),
+ // so it infers VARCHAR(0). But our `VarcharType` not allow precision
0.
+ new VarCharType(Math.max(1, relDataType.getPrecision))
Review comment:
Consider sql: `SELECT trim(LEADING from '') FROM T`
`SqlTrimFunction` use `ReturnTypes.cascade(ReturnTypes.ARG2,
SqlTypeTransforms.TO_NULLABLE, SqlTypeTransforms.TO_VARYING)` to infer return
type.
`TO_VARYING` just convert Char to VarChar and use previous precision which
maybe 0.
Now in Calcite, there is no limit to zero precision.
We need introduce an `ofEmptyLiteral()` to the variable length types as well.
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