On 19t of January, Heikki Linnakangas committed patch:
Make pg_relation_size() and friends return NULL if the object doesn't exist.
That avoids errors when the functions are used in queries like "SELECT
pg_relation_size(oid) FROM pg_class", and a table is dropped concurrently.
Continue reading Waiting for 9.2 – NULLS from pg_*_size() functions
On 19th of January Tom Lane committed really brilliant patch:
Add pg_table_size() and pg_indexes_size() to provide more user-friendly
wrappers around the pg_relation_size() function.
Bernd Helmle, reviewed by Greg Smith
Continue reading Waiting for 9.0 – table and index sizes