Adrian Klaver <adrian.klaver@aklaver.com> writes:
> So how does one go about using a table name from
> information_schema.tables in pg_table_size()?
You want something like
select pg_table_size(quote_ident(table_schema)||'.'||quote_ident(table_name))
from information_schema.tables;
I imagine that the failures you got are a consequence of having
some table names that aren't valid unless quoted (ie contain
spaces, funny characters, etc). In a general-purpose query,
you can't ignore the schema name either.
I might be more excited about v12's failure to provide an implicit
cast to regclass if there were any prospect of queries like this
working in a bulletproof way without accounting for schema names
and funny characters. But there isn't, so the query shown in SO
is a house of cards to start with. When you do it right, with
quote_ident() or format(), no special casting is needed.
regards, tom lane