Hello!
The Search Team in the Discovery Department is implementing a maximum search query length https://phabricator.wikimedia.org/T107947. There are two main reasons to do this:
1. Extremely long queries are almost always gibberish from things like malfunctioning scrapers. These queries skew our statistics about the usefulness of our search. Implementing a limit will reduce the magnitude of skew. 2. Extremely long queries have a disproportionate impact on performance. On its own this isn't enough, but considering point 1 above, limiting them is unlikely to impact any actual users. Implementing a limit will improve performance.
We've chosen a hard limit of 300 characters. If your query exceeds this, you will be told that your query exceeds the maximum length. Based on our analysis of typical query lengths https://phabricator.wikimedia.org/T107947#1515387, this change should impact almost nobody. If you think you'll be adversely affected, please reach out to us and we'll work with you to figure something out.
Thanks!
Dan