On Sat, Jun 07, 2014 at 08:35:27AM -0400, Gurjeet Singh wrote: > While reading [1] in context of Postgres Hibernator, I see that > Mitsuru mentioned one of the ways other RDBMS allows count(*) to be > driven by an index. > > > 'select /*+ INDEX(emp emp_pk) */ count(*) from emp;' to load index blocks > > I am not sure if Postgres planner already allows this,
It does: create table t (c, junk) as select *, repeat('a', 100) from generate_series(1,10000); alter table t add primary key (c); vacuum t; analyze t; explain select count(*) from t; -- Noah Misch EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers