Large Spreadsheet Streaming

Overview

Loading very large spreadsheets (e.g. millions of populated cells) into memory can lead to out-of-memory errors in 32-bit processes; HotXLS provides streaming readers and writers with near-constant memory usage, bypassing DOM generation during workbook parsing

Direct Reader API

The TXLSDirectReader class parses workbook streams sequentially without creating in-memory cell models; it fires events as cells are encountered

procedure Read(AStream: TStream; ACallback: TXLSDirectReadCallback);

This allows you to scan sheet rows sequentially and abort early when the target data boundaries are resolved

Direct Writer API

The TXLSDirectWriter class writes rows directly into the ZIP file package, ensuring minimal memory overhead when generating large data exports