Duplicate entry error when functino _swish_do_update called in cron

there are two issues should be paid attention in future development.

function _swish_do_update() {
  // Find all files available to the system
  $file_result = db_query("SELECT * FROM {files}");

  while ($file = db_fetch_array($file_result)) {
    // Determine if full text information is already available
    if (!db_result(db_query("SELECT `fulltext` from {swish_fulltext} WHERE filepath = '%s' AND nid = %d",$file['filepath'],$file['nid']))) {
.......

I don't think files table has nid column, maybe you meant to use fid column?

.......
      if(db_result(db_query("SELECT nid FROM {swish_fulltext} WHERE filepath = '%s' AND nid = %d", $file['filepath'], $file['nid']))) {
        db_query("UPDATE {swish_fulltext} SET `fulltext` = '%s' WHERE `filepath` = '%s'",$text, $file['filepath']);
      } else {
        db_query("INSERT INTO {swish_fulltext} (filepath,nid,`fulltext`) VALUES ('%s',%d,'%s')",$file['filepath'],$file['nid'],$text);
.......

it always goes to INSERT even there is result.