data Target(keep=document_id a b c);
    length a 8 document_id 8;
	if _N_=1 then do;
	  declare hash h(dataset: "work.Small", hashexp: 6);
	  h.definekey("document_id");
	  h.defineData("a");
	  h.defineDone();
	  call missing(document_id, a);
	end;
	set docs.Large;
        rc=h.find(Key: document_id);
	if (rc=0) then do;
           b=strip(a)||', '||b;
	   c=c;
	   output;
         end;
  run;