Re: BUG #13830: pg_table_size and pg_indexes_size

foggyglass@163.com writes:
> postgres=# create table b(id int);
> CREATE TABLE
> postgres=# create index b_idx on b(id);
> CREATE INDEX
> postgres=# select relname , pg_table_size(oid),pg_indexes_size(oid)
> postgres-# from pg_class where relname in ('b','b_idx');
>  relname | pg_table_size | pg_indexes_size
> ---------+---------------+-----------------
>  b       |             0 |            8192
>  b_idx   |          8192 |               0
> (2 rows)

Seems fine to me.  b is empty at this point, so it has size zero.
btree indexes, on the other hand, never have size zero because their
metapage is created immediately.  b_idx has no indexes attached to it,
so pg_indexes_size finds nothing to report on and returns zero for
that.

If you insert any actual data, the results change:

regression=# insert into b values(33);
INSERT 0 1
regression=#  select relname , pg_table_size(oid),pg_indexes_size(oid)  from pg_class where relname in ('b','b_idx');
 relname | pg_table_size | pg_indexes_size
---------+---------------+-----------------
 b       |          8192 |           16384
 b_idx   |         16384 |               0
(2 rows)

which maybe looks a bit saner.

            regards, tom lane