Internal function returning pg_statistic

Hi hackers,

Working on global temporary table I need to define function which 
returns set of pg_statistic records.
Unfortunately I failed to declare such function!
Type pg_statistic is defined in postgres.bki so I was not able to refer 
to it in pg_proc.dat file.
And if I explicitly enumerate columns of this type:


{ oid => '3434',
   descr => 'show local statistics for global temp table',
   proname => 'pg_gtt_statistic_for_relation', provolatile => 'v', 
proparallel => 'u',
   prorettype => 'record', proretset => 't', proargtypes => 'oid',
   proallargtypes => 

'{oid,oid,int2,bool,float4,int4,float4,int2,int2,int2,int2,int2,oid,oid,oid,oid,oid,oid,oid,oid,oid,oid,_float4,_float4,_float4,_float4,_float4,anyarray,anyarray,anyarray,anyarray,anyarray}',
   proargmodes => 
'{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
   proargnames => 

'{relid,starelid,staattnum,stainherit,stanullfrac,stawidth,stadistinct,stakind1,stakind2,stakind3,stakind4,stakind5,staop1,staop2,staop3,staop4,staop5,stacoll1,stacoll2,stacoll3,stacoll4,stacoll5,stanumbers1,stanumbers2,stanumbers3,stanumbers4,stanumbers5,stavalues1,stavalues2,stavalues3,stavalues4,stavalues5}',
   prosrc => 'pg_gtt_statistic_for_relation' },

then I go the following error when try to use this function:

   a column definition list is required for functions returning "record" 
at character 111

The column definition list provided in pg_proc.dat was rejected because 
it contains reference to anyarray which can not be resolved.

If I try to declare function in system_views.sql as returning setof 
pg_statistic then I got error "cannot change return type of existing 
function".

CREATE OR REPLACE FUNCTION
    pg_gtt_statistic_for_relation(relid oid) returns setof pg_statistic
LANGUAGE INTERNAL STRICT
AS 'pg_gtt_statistic_by_relation';

And if I try to declare it as returning record and explicitly cast it to 
pg_statistic, then reported error is "cannot cast type record to 
pg_statistic".

So the only possible way I found is to create extension and define 
function in this extension.
I wonder if there is some better solution?

Thanks in advance,

-- 
Konstantin Knizhnik
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company