Thread: Returns setof record PG/PLSQL

In my quest to create a function that counts rows for all user tables in
the database, I've written the following:
--
drop function generate_table_count ();
create or replace function generate_table_count () returns setof record
as '
declare
  tname record;
  count record;
  table text;
begin
    for tname in select table_name from information_schema.tables
               where table_schema = ''public'' loop
        for count in execute ''select ''''''  ||
        quote_ident(tname.table_name)     ||
        '''''' as name, count(*)  from '' ||
        quote_ident(tname.table_name) loop
            table := count.name;
            return next;
        end loop;
    end loop;
    return;
end;
' language plpgsql;
--

Problem is, I can't figure out what parameters to pass to "return next;"
to make this return properly, and can't find an example in the
documentation.  I have it working by defining the function to return
"setof text" and then do return next as:

--
return next table || '' '' || count.count;
--

However, I really want each result (table name and count) to have it's
own column.

Can someone help me out or point me in the direction of documentation
that will show an example?  It shouldn't be this hard, it seems.

Thanks, as always, for your help,
John

On Sun, 2005-08-14 at 18:56 -0400, John Wells wrote:
> In my quest to create a function that counts rows for all user tables in
> the database, I've written the following:

Based on another example I've found, I've tried the two following
variations (to no avail).  Getting "ERROR:  wrong record type supplied
in RETURN NEXT" on both counts:

-- Variation 1 ----------------------------------------------
drop function generate_table_count ();
create TYPE rowcounts_t as (name TEXT, count int);
create or replace function generate_table_count () returns setof
rowcounts_t as '
declare
  tname record;
  count record;
  table text;
begin
    for tname in select table_name from information_schema.tables
               where table_schema = ''public'' loop
        for count in execute ''select ''''''  ||
        quote_ident(tname.table_name)::text ||
        '''''' as name, count(*)  from '' ||
        quote_ident(tname.table_name) loop
            return next count;
        end loop;
    end loop;
    return;
end;
' language plpgsql;
-- Variation 2 ----------------------------------------------
drop function generate_table_count ();
create TYPE rowcounts_t as (name TEXT, count TEXT);
create or replace function generate_table_count () returns setof
rowcounts_t as '
declare
  tname record;
  count record;
  table text;
begin
    for tname in select table_name from information_schema.tables
               where table_schema = ''public'' loop
        for count in execute ''select ''''''  ||
        quote_ident(tname.table_name)::text ||
        '''''' as name, count(*)::text  from '' ||
        quote_ident(tname.table_name) loop
            return next count;
        end loop;
    end loop;
    return;
end;
' language plpgsql;
--

Still struggling....any insight you might have is very much appreciated.
Thanks,
John

John Wells <jb@sourceillustrated.com> writes:
> In my quest to create a function that counts rows for all user tables in
> the database, I've written the following:
> --
> drop function generate_table_count ();
> create or replace function generate_table_count () returns setof record
> as '
> declare
>   tname record;
>   count record;
>   table text;
> begin
>     for tname in select table_name from information_schema.tables
>                where table_schema = ''public'' loop
>         for count in execute ''select ''''''  ||
>         quote_ident(tname.table_name)     ||
>         '''''' as name, count(*)  from '' ||
>         quote_ident(tname.table_name) loop
>             table := count.name;
>             return next;
>         end loop;
>     end loop;
>     return;
> end;
> ' language plpgsql;
> --

> Problem is, I can't figure out what parameters to pass to "return next;"
> to make this return properly,

I think you really want to use a named rowtype for the result.
Something like

regression=# create type table_count_result as (table_name text, count bigint);
CREATE TYPE
regression=# create or replace function generate_table_count ()
regression-# returns setof table_count_result as $$
regression$# declare
regression$#   tname record;
regression$#   count table_count_result;
regression$# begin
regression$#   for tname in select table_name from information_schema.tables
regression$#                where table_schema = 'public'  loop
regression$#     for count in execute 'select ' || quote_literal(tname.table_name) || ', count(*) from ' ||
quote_ident(tname.table_name) loop 
regression$#       return next count;
regression$#     end loop;
regression$#   end loop;
regression$#   return;
regression$# end$$ language plpgsql;
CREATE FUNCTION
regression=# select * from generate_table_count();
...

If you use "setof record" then you have to declare the result type in
the calling query, which is a pain in the neck.

In 8.1 it'll be possible to avoid the named rowtype by using OUT
parameters, but for now, this is the best solution.

            regards, tom lane

John,
I changed your function like follows (Postgresql V8.03)

drop function generate_table_count ();
drop type rowcounts_t;
create TYPE rowcounts_t as (name TEXT, count int);
create or replace function generate_table_count () returns setof
rowcounts_t as
$$
declare
 tname record;
 c rowcounts_t;
 table text;
 s text;
begin
    for tname in select table_name from information_schema.tables
              where table_schema = 'public' loop
       s = 'select \''  || quote_ident(tname.table_name)::text ||  '\' as name,\
 count(*)  from ' || quote_ident(tname.table_name) ;
  -- following line for debug only
  -- raise notice 's = %',s;
      for c in execute s
      loop
      return next c;
      end loop;
    end loop;
    return;
end;
$$ language plpgsql;

select * from generate_table_count();


---------- Original Message -----------
From: John Wells <jb@sourceillustrated.com>
To: pgsql-general <pgsql-general@postgresql.org>
Sent: Sun, 14 Aug 2005 20:36:15 -0400
Subject: Re: [GENERAL] Returns setof record PG/PLSQL

> On Sun, 2005-08-14 at 18:56 -0400, John Wells wrote:
> > In my quest to create a function that counts rows for all user tables in
> > the database, I've written the following:
>
> Based on another example I've found, I've tried the two following
> variations (to no avail).  Getting "ERROR:  wrong record type supplied
> in RETURN NEXT" on both counts:
>
> -- Variation 1 ----------------------------------------------
> drop function generate_table_count ();
> create TYPE rowcounts_t as (name TEXT, count int);
> create or replace function generate_table_count () returns setof
> rowcounts_t as '
> declare
>   tname record;
>   count record;
>   table text;
> begin
>     for tname in select table_name from information_schema.tables
>                where table_schema = ''public'' loop
>         for count in execute ''select ''''''  ||
>         quote_ident(tname.table_name)::text ||
>         '''''' as name, count(*)  from '' ||
>         quote_ident(tname.table_name) loop
>             return next count;
>         end loop;
>     end loop;
>     return;
> end;
> ' language plpgsql;
> -- Variation 2 ----------------------------------------------
> drop function generate_table_count ();
> create TYPE rowcounts_t as (name TEXT, count TEXT);
> create or replace function generate_table_count () returns setof
> rowcounts_t as '
> declare
>   tname record;
>   count record;
>   table text;
> begin
>     for tname in select table_name from information_schema.tables
>                where table_schema = ''public'' loop
>         for count in execute ''select ''''''  ||
>         quote_ident(tname.table_name)::text ||
>         '''''' as name, count(*)::text  from '' ||
>         quote_ident(tname.table_name) loop
>             return next count;
>         end loop;
>     end loop;
>     return;
> end;
> ' language plpgsql;
> --
>
> Still struggling....any insight you might have is very much appreciated.
> Thanks,
> John
>
> ---------------------------(end of broadcast)---------------------------
> TIP 6: explain analyze is your friend
------- End of Original Message -------

On Sun, 2005-08-14 at 20:53 -0400, Tom Lane wrote:
> regression=# create type table_count_result as (table_name text, count bigint);
> CREATE TYPE
> regression=# create or replace function generate_table_count ()
> regression-# returns setof table_count_result as $$
> regression$# declare
> regression$#   tname record;
> regression$#   count table_count_result;
> regression$# begin
> regression$#   for tname in select table_name from information_schema.tables
> regression$#                where table_schema = 'public'  loop
> regression$#     for count in execute 'select ' || quote_literal(tname.table_name) || ', count(*) from ' ||
quote_ident(tname.table_name) loop 
> regression$#       return next count;
> regression$#     end loop;
> regression$#   end loop;
> regression$#   return;
> regression$# end$$ language plpgsql;
> CREATE FUNCTION
> regression=# select * from generate_table_count();

Sweet mercy...success.  Thanks...my forehead was a bit bloody from all
the head bashing going on over here...

I have much to learn about pl/pgsql programming!

Thanks again!
John