Louis Kuang created CALCITE-4841:
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Summary: 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
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`).
Will send PR later.
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