On Tue, 14 Mar 2023 at 16:07, Ben Clements <benhasgonewalking@xxxxxxxxx> wrote: > Similar to your "TOP() and BOTTOM() aggregate" idea, you might find Erwin Brandstetter's solution using the LAST() aggregate function interesting: (https://dba.stackexchange.com/a/324646/100880) Interesting. Just note that ORDER BY aggregates cannot be parallelised and there are no shortcuts to just look for the highest / lowest ordered row. All rows in the group must be sorted and the aggregate will just take the first or last of those once the sort is done. The difference there (unless using PG16 and an index provides presorted input) is that there would be O(N log2 N) comparisons to perform the sort, where as the TOP() / BOTTOM() idea both allows parallelism and requires less memory and only requires O(N) comparisons. If performance is not too critical row now, then what you've found looks great. I just wanted to mention that as it may be a factor that matters at some point, even if it does not right now. David
