The awful truth about Wikimedia's article counts
The article counts of many Wikimedia wikis suddenly changed on 29 March 2015: as the Signpost reported at the time, sixty-five wikis fell below milestones tracked at the Wikimedia News Meta page, and three increased to new milestones. Among these wikis, the largest absolute changes were a decrease of 281,624 articles in the English Wikisource (a 27% drop) and an increase of 4421 entries in the Persian Wiktionary (an 8% rise). The most extreme relative changes were a 98% decrease in Sindhi Wikinews articles (from 749 to 13), and a 23% increase in Bengali Wiktionary entries (from 920 to 1134).
The proximate cause of the large changes was the running of a maintenance script that recounts articles from scratch. For several reasons the article counts reported by most Wikimedia wikis have long been inaccurate—many negligibly so, but some by ridiculously large amounts. The maintenance script corrected these inaccuracies on almost all of Wikimedia's content wikis (except Wikibooks), but because not all of the root causes of the incorrect counts have been fixed, the script will be run once per month to ensure that the article counts can no longer get too far off of their correct values for too long.
The three main reasons the article counts needed to be fixed are:
- The definition of what constitutes an "article" has varied in the past.
- The actual implementation of article counting in different parts of the MediaWiki software has been inconsistent.
- The article counts have never been recalculated for all Wikimedia wikis at once to fix the resulting problems.
What follows is a brief explanation of why the article counts became wrong over time, a description of what changes in article counts were actually observed when the counts were fixed, and some suggestions of what issues related to article counting the wider Wikimedia community may wish to discuss further. Further technical details are available at meta:Article counts revisited.