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https://issues.apache.org/jira/browse/CALCITE-4841?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17428385#comment-17428385
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Louis Kuang commented on CALCITE-4841:
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Maybe I am missing the registration somewhere. I thought the following happen:
CsvSchemaFactory --> CsvSchema --> CsvTable --> getRowType -->
CsvEnumerator.deduceRowType --> CsvFieldType.toType(typeFactory) -->
RelDataTypeFactoryImpl.createJavaType(BigDecimal.class) -->
JavaType(BigDecimal.class) --> getSqlTypeName -->
JavaToSqlTypeConversionRules.lookup(BigDecimal.class) --> SqlTypeName.DECIMAL
and similarly for the FileFieldType. This seems enough for `!describe FooTable`
to print the column type as `DECIMAL`
It's true that I have not registered BigDecimal.class in
RelDataTypeFactorImpl#CLASS_FAMILIES though. Is there a commit that I can use
to reference adding a new type to Calcite?
> Support numeric column type in CSV and File adapter
> ---------------------------------------------------
>
> Key: CALCITE-4841
> URL: https://issues.apache.org/jira/browse/CALCITE-4841
> Project: Calcite
> Issue Type: Improvement
> Components: csv-adapter, file-adapter
> Reporter: Louis Kuang
> Priority: Minor
> Labels: pull-request-available
> Time Spent: 40m
> Remaining Estimate: 0h
>
> Currently, the csv adapter does not support the numeric column type (see
> supported types in
> [CsvFieldType|https://github.com/apache/calcite/blob/4bc916619fd286b2c0cc4d5c653c96a68801d74e/file/src/main/java/org/apache/calcite/adapter/file/CsvFieldType.java#L35].
> Any type that is not supported will be interpreted by the
> [CsvEnumerator|https://github.com/apache/calcite/blob/master/file/src/main/java/org/apache/calcite/adapter/file/CsvEnumerator.java]
> as string.
> When dealing with decimal numbers, the currently most appropriate type is
> `double`. However, this is not accurate enough for financial data. This
> feature request proposes adding a `numeric` column type that will be
> implemented by the Java `BigDecimal` type (and by conversion in
> [JavaToSqlTypeConversionRules|https://github.com/apache/calcite/blob/4bc916619fd286b2c0cc4d5c653c96a68801d74e/core/src/main/java/org/apache/calcite/sql/type/JavaToSqlTypeConversionRules.java#L74]
> be represented as a `Decimal` SQL type). This allow financial data to be
> represented and computed more accurately (`BigDecimal` has higher precision
> than `double`).
> Please see sample implementation in PR.
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