We're currently seeing some incredibly long queries that are impractical to test and run. Find out an appropriate maximum query length and configure cirrus/mediawiki to reject or truncate queries longer than that.
There are two main reasons to limit the maximum query length:
- Manual analysis of the queries above a length of a few hundred characters shows almost all of them to be meaningless gibberish. Limiting that improves the quality of our statistics.
- Longer queries have a much larger impact on performance. Limiting them improves performance, with little downside considering point 1 about many of them being gibberish.
Many search engines, such as Google, implement extremely aggressive maximum query lengths for the above reasons.