> In a GROUP BY, you may have a few hundred million rows, but only a few hundred groups within them
ISWYM although that is rather a specific case. For your purposes though it may be a common case, I don't know.
> QuestDB organizes data sorted by time, so relying on insertion order may help to avoid redundant sorting if there is an ORDER BY clause with the timestamp column.
If data is already sorted and you have an 'order by' then just use the data directly – bingo, instant merge join, no hash table needed.
ISWYM although that is rather a specific case. For your purposes though it may be a common case, I don't know.
> QuestDB organizes data sorted by time, so relying on insertion order may help to avoid redundant sorting if there is an ORDER BY clause with the timestamp column.
If data is already sorted and you have an 'order by' then just use the data directly – bingo, instant merge join, no hash table needed.