Rewrite GROUP BY queries with constant keys

[puzpuzpuz]

Is your feature request related to a problem?

Our query engine should rewrite

SELECT 1, URL, COUNT(*) AS c FROM hits ORDER BY c DESC LIMIT 10;

to

SELECT 1, URL, c FROM (SELECT URL, COUNT(*) AS c FROM hits ORDER BY c DESC LIMIT 10);

or

SELECT 1, URL, c FROM (SELECT URL, COUNT(*) AS c FROM hits) ORDER BY c DESC LIMIT 10;

The latter queries are more efficient due to smaller hash table key which opens up opportunity to use a specialized hash table implementation, but even within the same hash table implementation having less key columns is beneficial.

Describe the solution you'd like.

No response

Describe alternatives you've considered.

No response

Full Name:

Andrei Pechkurov

Affiliation:

QuestDB

Additional context

No response