PJ Fanning created DRILL-8071:
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Summary: format-excel should use POI DataFormatter
Key: DRILL-8071
URL: https://issues.apache.org/jira/browse/DRILL-8071
Project: Apache Drill
Issue Type: Improvement
Components: Execution - Data Types
Reporter: PJ Fanning
The existing ExcelBatchReader uses the raw data values from the cells. This raw
data ignores formatting set on the cells. As an example, numbers and dates are
stored as doubles. With the POI DataFormatter, you can get the cell style
applied so that the data will appear as it does when you view the data in Excel
itself.
[https://poi.apache.org/apidocs/dev/org/apache/poi/ss/usermodel/DataFormatter.html#formatCellValue-org.apache.poi.ss.usermodel.Cell-]
A big number like 123456789.987654 could be stored as double that is more like
123456789.9876539999999 when represented in decimal format (because this might
be the closest match that double can represent). The cell format could say that
cell has 6 decimal places after the decimal point so the formatter would round
the number back to the value that it displayed in Excel as.
Code that processes excel files is a real pain to get right because the
Microsoft storage format is really bad.
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