dynamically generated SQL and planner/performance

[Ivan Sergio Borgonovo <mail@xxxxxxxxxxxxxxx>]

I've a lot of code that should call different functions according to
values in tables.

something like:


create table FuncName(Name varchar(10), arg int);

insert into FuncName values('ciro',5);
insert into FuncName values('pino',7);
insert into FuncName values('nano',11);

create or replace function ciro(arg int, out res int) as
$$
begin
  res:=arg;
  return;
end;
$$ language plpgsql;

create or replace function pino(arg int, out res int) as
$$
begin
  res:=arg*2;
  return;
end;
$$ language plpgsql;

create or replace function nano(arg int, out res int) as
$$
begin
  res:=arg*4;
  return;
end;
$$ language plpgsql;


create or replace function FBuilder(out res int) as
$$
declare
  statement varchar(256);
  _Name varchar(10);
  _arg int;
begin
  select into _Name, _arg Name, arg from FuncName order by random();
  statement := ' select * from ' || _Name || '(' || _arg || ')';
  execute statement into res;
  return;
end;
$$ language plpgsql;

select * from FBuilder();

I don't understand which impact will have on the planner, caching
etc... generating the statement dynamically.

Will the execution of ciro, pino e nano be affected?
Or will just the plan for executing FBuilder statement be affected?

thanks

-- 
Ivan Sergio Borgonovo
http://www.webthatworks.it


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