Wrong result for query with like and %

Question

I have a strange problem with query with like and %.
When I run this script:
ALTER SESSION SET NLS_SORT = 'BINARY_CI';
ALTER SESSION SET NLS_COMP = 'LINGUISTIC';
-- SELECT * FROM NLS_SESSION_PARAMETERS;
-- drop table test1;
CREATE TABLE TEST1(K1 NVARCHAR2(80));
INSERT INTO TEST1 VALUES ('gsdk');
INSERT INTO TEST1 VALUES ('ąxyz');
INSERT INTO TEST1 VALUES ('ŁFa');
INSERT INTO TEST1 VALUES ('ła');
INSERT INTO TEST1 VALUES ('Śab');
INSERT INTO TEST1 VALUES ('Śrrrb');
commit;
select * from TEST1 where k1 like N'Ł%';
I get this:
K1
ŁFa
ła
Śab <- WRONG
Śrrrb <- WRONG
4 rows selected
When i change datatype to varchar2 this code work correct.
Is this a bug or what ?
The execution plan:
PLAN_TABLE_OUTPUT
SQL_ID d3d64aupz4bb5, child number 2
select * from TEST1 where k1 like N'Ł%'
Plan hash value: 4122059633
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | | | 2 (100)| |
|* 1 | TABLE ACCESS FULL| TEST1 | 1 | 82 | 2 (0)| 00:00:01 |
Predicate Information (identified by operation id):
1 - filter((NLSSORT("K1",'nls_sort=''BINARY_CI''')>=HEXTORAW('014200'
) AND NLSSORT("K1",'nls_sort=''BINARY_CI''')<HEXTORAW('01610100') ))
Note
- dynamic sampling used for this statement (level=2)

Answer 1

DATABASE NLS CONFIGURATION:
NLS_CHARACTERSET AL32UTF8
NLS_NCHAR_CHARACTERSET     AL16UTF16
NLS_COMP     BINARY
NLS_SORT     BINARY
Oracle version 11.2.0.2.0