While CLUSTER is great for optimizing a given index, as of 9.1, it still requires an exclusive lock (no reads or writes). http://www.postgresql.org/docs/9.1/st

While CLUSTER is great for optimizing a given index, as of 9.1, it still requires an exclusive lock (no reads or writes). http://www.postgresql.org/docs/9.1/static/sql-cluster.html http://www.postgresql.org/docs/9.1/static/sql-cluster.html