Performance Improvements for Csv Reader #3769
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Investigating issue PHPOffice#381, a means was suggested to duplicated a problem, but no problem occurred ... except for performance. This involved a spreadsheet with a large number of cells, definitely not PhpSpreadsheet's strong point; even so, the program (entirely available in the issue) took a disastrous two or so hours to complete on my system. Looking at the Csv Reader code, several opportunities to cache results and avoid function calls jumped out, none of which seem to materially add to the maintenance burden of the program. Testing these changes resulted in a run time of about 20 minutes, still hardly a thing of beauty, but a huge improvement over the original and therefore worth proceeding with.
Test cases included duplicates, and didn't account for some things (e.g. French locale will treat both 'vrai' and 'true' as true).
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Investigating issue #381, a means was suggested to duplicated a problem, but no problem occurred ... except for performance. This involved a spreadsheet with a large number of cells, definitely not PhpSpreadsheet's strong point; even so, the program (entirely available in the issue) took a disastrous two or so hours to complete on my system. Looking at the Csv Reader code, several opportunities to cache results and avoid function calls jumped out, none of which seem to materially add to the maintenance burden of the program. Testing these changes resulted in a run time of about 20 minutes, still hardly a thing of beauty, but a huge improvement over the original and therefore worth proceeding with.
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