Aggregates that have to do full table scans are notoriously slow in Postgres due to how multi-version concurrency control is implemented.
Any time you comment out a WHERE clause on a big table while performing an aggregate report, Postgres chokes.
Any time you comment out a WHERE clause on a big table while performing an aggregate report, Postgres chokes.
Compared to InnoDB? You are incorrect, Postgres is faster, even for a raw count(*), even when comparing against the InnoDB plugin and not the ancient InnoDB builtin.
I have access to tuned TB+ DBs of both types and am happy to disprove any specific examples you can provide.