title: spreadsheets gets corrupted for large data
body: <p>i'm exporting data from my database into an excel file using php and pear extension libraries.
  it works fine when i download small quantity of data. but if the data is large then the excel sheet gets corrupted, (usually all url gets written in the same cell) the data i'm exporting is of type string, url or date.</p>
  
  <p>why is the excel sheet getting corrupted? </p>