### Problem
You want to return the top item from a sorted list in a BigQuery query, but your data
set is particularly large and the query is slow.
### Discussion
Although ROW_NUMBER() has a scalable implementation that can perform distributed
sorts across multiple BigQuery workers, the entire sort needs to be calculated. In par‐
ticularly large queries, using ARRAY_AGG allows BigQuery to drop unneeded data. This
is a BigQuery-specific trick to speed up sorts when you know you need only the top-n
results