postgresql - How to get function return type's length, precision and scale? -

i function return type catalog table this....

select proname, pg_get_function_result(p.oid) pg_proc p  join pg_namespace n on n.oid = p.pronamespace  n.nspname = 'someschema' , p.proname = 'somefunction' 

i return type's
a) length
b) precision
c) scale (if supported data type)

is possible pg_catalog or have take information_schema columns?

attention! precision , scale useless postgresql scalar functions, because ignored. type important.

 postgres=# create or replace function foo1() returns numeric(10,3) $$ begin   return 10.0/3.0; end; $$ language plpgsql; create function time: 39.511 ms postgres=# select foo1();         foo1         ────────────────────  3.3333333333333333 (1 row)  time: 0.910 ms postgres=# create or replace function foo2() returns varchar(2) $$ begin   return 'abcde'; end; $$ language plpgsql; create function time: 28.992 ms postgres=# select foo2();  foo2   ───────  abcde (1 row)  time: 0.746 ms 

only domain, can propagate (or ensure necessary casting) outer side of function:

 postgres=# create domain xx numeric(10,3); create domain postgres=# create or replace function foo4() returns xx $$ begin   return 10.0/3.0; end; $$ language plpgsql; create function time: 32.417 ms postgres=# select foo4();  foo4   ───────  3.333 (1 row) 

trick getting info used queries system catalog.

• run psql parameter -e
• use related \d* command

 bash-4.1$ psql.92 postgres -e psql.92 (9.2.2) type "help" help.  postgres=# \df ********* query ********** select n.nspname "schema",   p.proname "name",   pg_catalog.pg_get_function_result(p.oid) "result data type",   pg_catalog.pg_get_function_arguments(p.oid) "argument data types",  case   when p.proisagg 'agg'   when p.proiswindow 'window'   when p.prorettype = 'pg_catalog.trigger'::pg_catalog.regtype 'trigger'   else 'normal' end "type" pg_catalog.pg_proc p      left join pg_catalog.pg_namespace n on n.oid = p.pronamespace pg_catalog.pg_function_is_visible(p.oid)       , n.nspname  'pg_catalog'       , n.nspname  'information_schema' order 1, 2, 4; **************************                                          list of functions  schema │            name            │      result data type       │ argument data types │  type   ────────┼────────────────────────────┼─────────────────────────────┼─────────────────────┼────────  public │ f1                         │ void                        │                     │ normal  public │ foo1                       │ numeric                     │                     │ normal  public │ foo2                       │ character varying           │                     │ normal  public │ foo3                       │ numeric                     │ out result numeric  │ normal  public │ foo4                       │ xx                          │                     │ normal  public │ to_timestamp_ignore_errors │ timestamp without time zone │ text                │ normal  public │ xavg                       │ bigint                      │ integer             │ normal (7 rows)