why cant see my schema size

问题

If you google for "postgresql table size" you get this nice query. https://wiki.postgresql.org/wiki/Disk_Usage

SELECT *, pg_size_pretty(total_bytes) AS total
    , pg_size_pretty(index_bytes) AS INDEX
    , pg_size_pretty(toast_bytes) AS toast
    , pg_size_pretty(table_bytes) AS TABLE
  FROM (
  SELECT *, total_bytes-index_bytes-COALESCE(toast_bytes,0) AS table_bytes FROM (
      SELECT c.oid,nspname AS table_schema, relname AS TABLE_NAME
              , c.reltuples AS row_estimate
              , pg_total_relation_size(c.oid) AS total_bytes
              , pg_indexes_size(c.oid) AS index_bytes
              , pg_total_relation_size(reltoastrelid) AS toast_bytes
          FROM pg_class c
          LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
          WHERE relkind = 'r'
  ) a
) a;

I have a schema app:

But doesnt show in the result:

Why app schema doesnt show in the result?

I try a second query, and also returm empty result.

select table_name, pg_relation_size(table_name)
from information_schema.tables
where table_schema = 'app'
order by 2

回答1:

Unfortunately even psql command line tool does not show total size of all objects in schema. All commands like "\l+" for databases or "\dt+" for tables show in "+" form also total size. Only "\dn+" for schemas does not show size.

Select from pg_class is probably the best but do not filter only for "r" - schemas contain also indexes and other objects.

来源：https://stackoverflow.com/questions/40977776/why-cant-see-my-schema-size