> People expect count(*) _without a where clause_ to be cached in a single
> global variable. Postgres can't do this, but the reason has everything to do
Someone should write an approx_count('table') function that reads
reltuples from pg_class and tell them to use it in combination with
autovac.
I've yet to see someone use count(*) across a table and not round the
result themselves (approx 9 million clients).