mysql:[email protected] [enwiki]> select up_property, up_value, count(*) from user_properties where up_value = '' group by up_property order by count(*) desc limit 10;
+----------------------------------------+----------+----------+
| up_property                            | up_value | count(*) |
+----------------------------------------+----------+----------+
| echo-subscriptions-web-reverted        |          |  8645xxx |
| nickname                               |          |  1292xxx |
| variant                                |          |  1014xxx |
| gettingstarted-task-toolbar-show-intro |          |   792xxx |
| timecorrection                         |          |   743xxx |
| watchlisttoken                         |          |   434xxx |
| echo-subscriptions-push-ge-newcomer    |          |   270xxx |
| usecodemirror-colorblind               |          |   258xxx |
| twocolconflict                         |          |   241xxx |
| realme-urls                            |          |   149xxx |
+----------------------------------------+----------+----------+
10 rows in set (14 min 8.191 sec)

mysql:[email protected] [enwiki]> select up_value, count(*) from user_properties where up_property = 'skin' group by up_value order by count(*) desc limit 50;
+-------------+----------+
| up_value    | count(*) |
+-------------+----------+
| monobook    |  21986xx |
| vector      |   2548xx |
| cologneblue |    877xx |
| modern      |    859xx |
| vector-2022 |    347xx |
| timeless    |    286xx |
| minerva     |    175xx |
| 2           |     30xx |
+-------------+----------+
8 rows in set (39.426 sec)

Cleaning up invalid skin values for enwiki
7305884 are there
...

echo "Cleaning up invalid skin values"
counts=$(sql $1 -- -ss -e "select count(*) from user_properties where up_property='skin' and up_value in ('','0','1','amethyst','chick','myskin','nostalgia','simple','standard','minervaneue');")
echo "$counts are there"
for i in {0..10000}
do
  echo "Deleting batch $i"
  sql $1 --write -- -e "delete from user_properties where up_property='skin' and up_value in ('','0','1','amethyst','chick','myskin','nostalgia','simple','standard','minervaneue') LIMIT 10000;"
  echo "sleeping...zzz"
  sleep 5
  counts=$(sql $1 -- -ss -e "select count(*) from user_properties where up_property='skin' and up_value in ('','0','1','amethyst','chick','myskin','nostalgia','simple','standard','minervaneue');")
  echo "$counts left for $j"
  if [ "$counts" -eq 0 ]; then
      echo "Done"
      break
  fi
done

mysql:[email protected] [arwiki]> select up_value, count(*) from user_properties where up_property  = 'skin' group by up_value order by count(*) desc;
+-------------+----------+
| up_value    | count(*) |
+-------------+----------+
|             |   1648xx |
| monobook    |    356xx |
| vector      |     49xx |
| modern      |     25xx |
| vector-2022 |      8xx |
| chick       |      8xx |
| cologneblue |      8xx |
| timeless    |      6xx |
| minerva     |      5xx |
| simple      |      4xx |
| nostalgia   |      4xx |
| myskin      |      3xx |
| 0           |      2xx |
| amethyst    |     tiny |
| 2           |     tiny |
+-------------+----------+
15 rows in set (0.828 sec)