I have just started using PHPExcel to try to read data for application development. I have found that a few of my libreoffice calc 3.4 spreadsheets can be read quickly while most take a very long time. None of these spreadsheets are that large as far as worksheet, row and column use. I found that although none of my worksheets use more that 60 rows, the ones that PHPExcel seems to have difficulty with display 1048576 rows being used. Not only does this cause the data to load more slowly in PHPExcel, but I believe that it also causes much more system memory to be allocated trying to read the cells from these unused rows.
I seem to have traced source of the problem to having previously formatted entire columns instead of just the required number of rows. This changed something in the spreadsheet file. I have tried various means of clearing the formatting in test spreadsheets, but it seems that once formatted, the only way to fix it is to move the data to a new spreadsheet. Even deleting the formatted columns doesn't work I am concerned that I may end up with corrupted data using this method however. Can anyone suggest a better way to "unformat" these unused rows so that PHPExcel won't keep trying to read them? Thanks in advance