My Drupal 7 batch processing code is repeating the final iteration of the batch process over and over. Can someone help me fix it?

I'm trying to move data from an old database to a new one. My code doesn't currently write anything (which is fine), but the reading repeats over and over on the last record even though $context['finished'] is set to 1. Any idea what I'm doing wrong?

<?php
function ogamigrate_permission() {
  return array(
    'migrate to oga2' => array(
      'title' => t('OGA 1.x -> OGA 2.0 Data Migration'),
      'description' => t('Migrate data from the old site.'),
    ),
  );
}

function ogamigrate_menu() {
  $items['admin/ogamigrate'] = array(
    'page callback' => '_ogamigrate_batch',
    'access arguments' => array('migrate to oga2'),
  );

  $items['admin/ogamigrate/finished'] = array(
    'page callback' => '_ogamigrate_complete',
    'access arguments' => array('migrate to oga2'),
  );
  return $items;
}

function _ogamigrate_batch() {
  $batch = array(
    'title' => t('Migrating data from OGA 1'),
    'operations' => array(
      array('_ogamigrate_tags', array()),
      #array('my_function_2', array()),
   ),
    'finished' => '_ogamigrate_finished',
  );
  batch_set($batch);
  batch_process('admin/ogamigrate/finished');
}

function _ogamigrate_tags(&$context) {
  db_set_active('old');
  if (empty($context['sandbox'])) {
    $context['sandbox']['progress'] = 0;
    $context['sandbox']['current_tid'] = 0;
    $context['sandbox']['max'] = db_query('select max(tid) from {term开发者_运维技巧_data} where vid in (3, 4, 6, 7, 10);')->fetchField();
  }

  error_log("migrating tid {$context['sandbox']['current_tid']} ({$context['finished']}");

  $limit = 5;

  $result = db_select('term_data')
  ->fields('term_data', array('tid', 'name', 'description'))
  ->condition('tid', $context['sandbox']['current_tid'], '>')
  ->condition('vid', array(3, 4, 6, 7, 10), 'in')
  ->orderBy('tid')
  ->range(0, $limit)
  ->execute();

  db_set_active('default');

  foreach ($result as $row) {
    #$node = node_load($row->nid, NULL, TRUE);
   error_log("Processing tid {$row->tid} / {$context['sandbox']['max']} ({$row->name})");
    $context['results'][] = $row->tid . ' : ' . $row->name;
    $context['sandbox']['progress']++;
    $context['sandbox']['current_tid'] = $row->tid;
    $context['message'] = $row->name;
  }

  if ($context['sandbox']['progress'] != $context['sandbox']['max']) {
    $context['finished'] = $context['sandbox']['progress'] / $context['sandbox']['max'];
  }
}

function _ogamigrate_finished($success, $results, $operations) {
  error_log('finished');
  if ($success) {
    $message = format_plural(count($results), 'One item processed.', '@count item processed.');
  }
  else {
    $message = t('Finished with an error.');
  }
  drupal_set_message($message);
  /*
  // Providing data for the redirected page is done through $_SESSION.
  foreach ($results as $result) {
    $items[] = t('Loaded node %title.', array('%title' => $result));
  }
  $_SESSION['my_batch_results'] = $items;
  */
}

function _ogamigrate_complete() {
  return "<p>Migration complete.</p>";
}

Of course, I spend hours trying to figure this out and the minute I post it I figure out what I was doing wrong.

Here's the deal: I was incrementing 'progress' every time I added a record, but since I wasn't including every single taxonomy vocabulary, it was actually skipping over some records, which means that 'progress' was never quite adding up to 'max', since 'max' was a record ID and not just a total number of records. :p