When POI reads spreadsheets, the entire data is stored in memory to allow random access to specific rows. Reading large files can therefore lead to out-of-memory exceptions.

POI does have a streaming API for reading XLSX but it is complex to use.

However, a third-party POI wrapper - excel-streaming-reader - now exists which makes this much easier.

Integrate this library and use it to support a new readLargeFile() method able to read large XLSX files with less likelihood of running out of memory.

Limitations

• Only works with XLSX files
• Only works with Lucee (ACF throws an exception for reasons I have been unable to fathom)
• Can only return a query object, CSV or HTML (not a workbook object, because too many of the expected POI methods are unsupported by the wrapper)
• Doesn't support all read() options, in particular specifying rows or columns (i.e. it reads the entire sheet)