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XlsxWorksheet constructor is parsing the whole sheet on construction #618

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XlsxWorksheet constructor is parsing the whole sheet on construction#618
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performance
Milestone
4.0
@OwnageIsMagic

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@OwnageIsMagic
OwnageIsMagic
opened on Nov 20, 2022

ExcelDataReader/src/ExcelDataReader/Core/OpenXmlFormat/XlsxWorksheet.cs

Lines 38 to 71 in 2f14bd4

while ((record = sheetStream.Read()) != null)
{
switch (record)
{
case SheetDataBeginRecord _:
inSheetData = true;
break;
case SheetDataEndRecord _:
inSheetData = false;
break;
case RowHeaderRecord row when inSheetData:
rowIndexMaximum = Math.Max(rowIndexMaximum, row.RowIndex);
break;
case CellRecord cell when inSheetData:
columnIndexMaximum = Math.Max(columnIndexMaximum, cell.ColumnIndex);
break;
case ColumnRecord column:
columnWidths.Add(column.Column);
break;
case SheetFormatPrRecord sheetFormatProperties:
if (sheetFormatProperties.DefaultRowHeight != null)
DefaultRowHeight = sheetFormatProperties.DefaultRowHeight.Value;
break;
case SheetPrRecord sheetProperties:
CodeName = sheetProperties.CodeName;
break;
case MergeCellRecord mergeCell:
cellRanges.Add(mergeCell.Range);
break;
case HeaderFooterRecord headerFooter:
HeaderFooter = headerFooter.HeaderFooter;
break;
}
}

So basically calling reader.NextResult() is contributing 50% time of my workload and allocating tons of Cell, Cell[] and boxed double for worksheet I even don't want to read.

Profiler result

image

Maybe make those properties lazy calculated?

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