Мне, правда, не совсем понятно, почему LENGTHB(LPAD('Ф', 4000, 'Ф')) показывает 4000

select length(rpad('яяя',50,'-')) as aaa,length(rpad(n''||'яяя',50,'-')) as bbb,lengthb(rpad(n''||'яяя',50,'-')) as ccc,lengthb(rpad('яяя',50,'-')) as ddd
from dual

       AAA        BBB        CCC        DDD
---------- ---------- ---------- ----------
        47         50        100         50

create table t_test_varchar (counter number(5));
declare 
l varchar2(32676);
begin
    execute immediate 'truncate table t_test_varchar';
    insert into t_test_varchar values (0);
    for i in 1..32676 loop
    update t_test_varchar set counter=i;
    commit;
       if(i<10000) then l:=l||'F'; else  l:=l||'Ф'; end if;
    end loop;
end;
/
Error at line 1
ORA-06502: PL/SQL: numeric or value error: character string buffer too small
ORA-06512: at line 9

select * from t_test_varchar
   COUNTER
----------
     21384

select length('Ф') l , lengthb('Ф') lb , length(lpad(cast('5' as varchar2(1) ), 100000000, '5')) lmax, lengthb(lpad(cast('5' as varchar2 (1) ), 100000000, 'Ф')) lmaxb , length(lpad(cast('Ф' as nvarchar2(1) ), 100000000, 'Ф')) lmaxN, lengthb(lpad(cast('Ф' as nvarchar2 (1) ), 100000000, 'Ф')) lmaxbN from dual;

         L         LB       LMAX      LMAXB      LMAXN     LMAXBN
---------- ---------- ---------- ---------- ---------- ----------
         1          2       4000       4000       2000       4000

[oracle@xxxxx ~]$ export NLS_LANG=AMERICAN_AMERICA.AL32UTF8
[oracle@xxxxx ~]$ env|grep LANG
NLS_LANG=AMERICAN_AMERICA.AL32UTF8
LANG=en_US.UTF-8
[oracle@xxxxx ~]$ sqlplus "/as sysdba"

SQL*Plus: Release 11.2.0.4.0 Production on Fri Feb 19 13:04:22 2016

Copyright (c) 1982, 2013, Oracle.  All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> select VALUE from nls_database_parameters where parameter='NLS_CHARACTERSET'
union select VALUE from nls_session_parameters where parameter='NLS_LENGTH_SEMANTICS' ;

VALUE
--------------------------------------------------------------------------------
AL32UTF8
CHAR

SQL> SET LINESIZE 32000;
SQL> select lengthc(rpad('я',5,'-')) as aaa
,lengthc(rpad(convert(chr(223),'AL32UTF8','CL8MSWIN1251'),5,'-')) as bbb
,lengthc(rpad(n''||convert(chr(223),'AL32UTF8','CL8MSWIN1251'),5,'-')) as ccc
,dump('я'),dump(rpad('я',5,'-'))
,dump(convert(chr(255),'AL32UTF8','CL8MSWIN1251')) as dump_fromChar
,dump(rpad(convert(chr(255),'AL32UTF8','CL8MSWIN1251'),5,'-')) as dump_RPadfromChar from dual;

       AAA        BBB        CCC DUMP('Я')                  DUMP(RPAD('Я',5,'-'))                 DUMP_FROMCHAR          DUMP_RPADFROMCHAR
---------- ---------- ---------- -------------------------- ------------------------------------- ---------------------- ----------------------------------------
         5          5          5 Typ=96 Len=2: 209,143      Typ=1 Len=6: 209,143,45,45,45,45      Typ=1 Len=2: 209,143   Typ=1 Len=6: 209,143,45,45,45,45

SQL> Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
[oracle@xxxxx ~]$ . /etc/profile
[oracle@xxxxx ~]$ env|grep LANG
NLS_LANG=AMERICAN_AMERICA.AL32UTF8
LANG=en_US.UTF-8
[oracle@xxxxx ~]$ sqlplus "/as sysdba"

SQL*Plus: Release 12.1.0.2.0 Production on Fri Feb 19 13:06:00 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

SQL> select VALUE from nls_database_parameters where parameter='NLS_CHARACTERSET' union select VALUE from nls_session_parameters where parameter='NLS_LENGTH_SEMANTICS' ;

VALUE
--------------------------------------------------------------------------------
AL32UTF8
CHAR


SQL> SET LINESIZE 32000;
SQL> select lengthc(rpad('я',5,'-')) as aaa
,lengthc(rpad(convert(chr(223),'AL32UTF8','CL8MSWIN1251'),5,'-')) as bbb
,lengthc(rpad(n''||convert(chr(223),'AL32UTF8','CL8MSWIN1251'),5,'-')) as ccc
,dump('я')
,dump(rpad('я',5,'-'))
,dump(convert(chr(255),'AL32UTF8','CL8MSWIN1251')) as dump_fromChar
,dump(rpad(convert(chr(255),'AL32UTF8','CL8MSWIN1251'),5,'-')) as dump_RPadfromChar from dual;

       AAA        BBB        CCC DUMP('Я')                 DUMP(RPAD('Я',5,'-'))          DUMP_FROMCHAR            DUMP_RPADFROMCHAR
---------- ---------- ---------- ------------------------- ------------------------------ ------------------------ ----------------------------------
         4          4          5 Typ=96 Len=2: 209,143     Typ=1 Len=5: 209,143,45,45,45  Typ=1 Len=2: 209,143     Typ=1 Len=5: 209,143,45,45,45

SQL>