Prints number of rows in each table on given scheme

num_of_rows.sql

DECLARE
  n NUMBER;
BEGIN
  FOR rec IN (SELECT owner,
                     table_name
                FROM all_tables WHERE owner = 'OWNER') -- replace OWNER with target schema
  LOOP
    EXECUTE IMMEDIATE 'begin
     select count(*) into :n from '||
      rec.owner||'.'||rec.table_name||';
     end;'
    USING OUT n;
    dbms_output.put_line(rec.owner||'.'||rec.table_name||' - '||n);
  END LOOP;
END;
/