Getting errors like:
```
Nov 28 19:11:39 mw1191: [Mon Nov 28 19:11:39 2016] [hphp] [4640:7f5bfd3ff700:132019:000001] [] \nWarning: [data-update-failed]: A data update callback triggered an exception (A database query error has occurred. Did you forget to run your application's database schema updater after upgrading? \nQuery: DELETE FROM `wb_terms` WHERE term_language = 'zh-hans' AND term_type = 'label' AND term_text = '\xe6\xa8\xa1\xe6\x9d\xbf:Country data Saxony' AND term_entity_id = '25722070' AND term_entity_type = 'item'\nFunction: Wikibase\\TermSqlIndex::deleteTerms\nError: 1213 Deadlock found when trying to get lock; try restarting transaction (10.64.16.144)\n) [Called from Wikibase\\Updates\\DataUpdateAdapter::doUpdate in /srv/mediawiki/php-1.29.0-wmf.3/extensions/Wikidata/extensions/Wikibase/repo/includes/updates/DataUpdateAdapter.php at line 73] in /srv/mediawiki/php-1.29.0-wmf.3/includes/debug/MWDebug.php on line 311
```
This happens occasionally:
```
$ zgrep -cF 'Wikibase\\TermSqlIndex::deleteTerms\nError' archive/hhvm.log-201611*
archive/hhvm.log-20161101.gz:0
archive/hhvm.log-20161102.gz:0
archive/hhvm.log-20161103.gz:1
archive/hhvm.log-20161104.gz:1
archive/hhvm.log-20161105.gz:0
archive/hhvm.log-20161106.gz:1
archive/hhvm.log-20161107.gz:0
archive/hhvm.log-20161108.gz:2
archive/hhvm.log-20161109.gz:1
archive/hhvm.log-20161110.gz:0
archive/hhvm.log-20161111.gz:0
archive/hhvm.log-20161112.gz:0
archive/hhvm.log-20161113.gz:2
archive/hhvm.log-20161114.gz:0
archive/hhvm.log-20161115.gz:0
archive/hhvm.log-20161116.gz:1
archive/hhvm.log-20161117.gz:0
archive/hhvm.log-20161118.gz:2
archive/hhvm.log-20161119.gz:0
archive/hhvm.log-20161120.gz:1
archive/hhvm.log-20161121.gz:0
archive/hhvm.log-20161122.gz:3
archive/hhvm.log-20161123.gz:3
archive/hhvm.log-20161124.gz:0
archive/hhvm.log-20161125.gz:3
archive/hhvm.log-20161126.gz:1
archive/hhvm.log-20161127.gz:3
```
This could probably be solved by collecting primary keys first (maybe even from a replica) and later on deleting by PK (in `TermSqlIndex::deleteTerms` and `TermSqlIndex::deleteTermsOfEntity`)