--
--   Licensed to the Apache Software Foundation (ASF) under one or more
--   contributor license agreements.  See the NOTICE file distributed with
--   this work for additional information regarding copyright ownership.
--   The ASF licenses this file to You under the Apache License, Version 2.0
--   (the "License"); you may not use this file except in compliance with
--   the License.  You may obtain a copy of the License at
--
--      http://www.apache.org/licenses/LICENSE-2.0
--
--   Unless required by applicable law or agreed to in writing, software
--   distributed under the License is distributed on an "AS IS" BASIS,
--   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
--   See the License for the specific language governing permissions and
--   limitations under the License.
--
------------------------------------------------------------------------------
-- 2 CONCURRENT USER TESTS of READ UNCOMMITTED TESTS
--
-- each test assumes calling script has set up a writer connection, it is
-- expected the calling script(s) will vary the isolation of the writer 
-- connection to test the interaction of read uncommitted with various isolation
-- levels.
-- 
-- overview:
--  TEST 0: test RU(read uncommitted) heap read interaction insert/delete/update
--  TEST 1: test RU(read uncommitted) heap read interaction insert/delete/update
--  TEST 2: test RU(read uncommitted) ddl interaction
--
------------------------------------------------------------------------------

-- SCRIPT SETUP
connect 'wombat' as iso_read_uncommitted;
autocommit off;
commit;

------------------------------------------------------------------------------
--  TEST 0: test RU(read uncommitted) heap read interaction insert/delete/update
------------------------------------------------------------------------------

-- set up
set connection iso_read_uncommitted;
autocommit off;
set isolation read uncommitted;
create table test_0 (a int);
insert into test_0 values (1);
commit;

-- READ UNCOMMITTED CONNECTION:
-- read uncommitted should maintain no lock on the row.
set connection iso_read_uncommitted;
select * from test_0;

CALL SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY('derby.language.bulkFetchDefault','1');
get cursor scan_cursor as 
    'select a from test_0'; 
call SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY('derby.language.bulkFetchDefault', '16');
next scan_cursor;

-- WRITER CONNECTION:
set connection writer;
-- writer should not be blocked.
insert into test_0 values (2);

-- serializable: update will get table level lock so will be blocked.
-- other iso: writer should in no way be blocked by reader.
update test_0 set a = 3 where a = 1;

-- READ UNCOMMITTED CONNECTION:
-- next in cursor should see the new uncommitted row just inserted (2)
set connection iso_read_uncommitted;
next scan_cursor;

-- full select should see the update and the new row.
select * from test_0;

-- WRITER CONNECTION:
-- delete the row that the read uncommitted connection is positioned on.
set connection writer;

-- serializable: update will get table level lock so will be blocked.
-- other iso: writer should in no way be blocked by reader.
delete from test_0 where a = 2;

-- READ UNCOMMITTED CONNECTION:
-- next in cursor should get to end of scan.
set connection iso_read_uncommitted;
next scan_cursor;
close scan_cursor;

-- full select should see just one row.
select * from test_0;

-- WRITER CONNECTION:
set connection writer;
rollback;

-- READ UNCOMMITTED CONNECTION:
-- should now see original rows - note all of this in same xact.
set connection iso_read_uncommitted;
select * from test_0;

-- cleanup
set connection iso_read_uncommitted;
commit;
set connection writer;
commit;
drop table test_1;
commit;

------------------------------------------------------------------------------
--  TEST 1: test RU(read uncommitted) heap read interaction insert/delete/update
------------------------------------------------------------------------------

-- set up
set connection iso_read_uncommitted;
autocommit off;
set isolation read uncommitted;
create table test_1 (a int, b int);
insert into test_1 values (1, 1);
create index test_1_idx on test_1 (a);
commit;

-- READ UNCOMMITTED CONNECTION:
-- read uncommitted should maintain no lock on the row.
set connection iso_read_uncommitted;
select * from test_1;

CALL SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY('derby.language.bulkFetchDefault','1');
get cursor scan_cursor as 
    'select a from test_1'; 
call SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY('derby.language.bulkFetchDefault', '16');
next scan_cursor;

-- WRITER CONNECTION:
set connection writer;
-- writer should not be blocked.
insert into test_1 values (2, 2);

-- writer should in no way be blocked by reader.
update test_1 set b = 10 where a = 1;

-- READ UNCOMMITTED CONNECTION:
-- next in cursor should see the new uncommitted row just inserted (2)
set connection iso_read_uncommitted;
next scan_cursor;

-- full select should see the update and the new row.
select * from test_1;

-- WRITER CONNECTION:
-- delete the row that the read uncommitted connection is positioned on.
set connection writer;

-- writer should in no way be blocked by reader.
delete from test_1 where a = 2;

-- READ UNCOMMITTED CONNECTION:
-- next in cursor should get to end of scan.
set connection iso_read_uncommitted;
next scan_cursor;
close scan_cursor;

-- full select should see just one row.
select * from test_1;

-- WRITER CONNECTION:
set connection writer;
rollback;

-- READ UNCOMMITTED CONNECTION:
-- should now see original rows - note all of this in same xact.
set connection iso_read_uncommitted;
select * from test_1;

-- cleanup
set connection iso_read_uncommitted;
commit;
set connection writer;
commit;
drop table test_1;
commit;

------------------------------------------------------------------------------
--  TEST 2: test RU(read uncommitted) ddl interaction
------------------------------------------------------------------------------

-- set up
set connection iso_read_uncommitted;
autocommit off;
set isolation read uncommitted;
create table test_2 (a int);
insert into test_2 values (1);
commit;

-- READ UNCOMMITTED CONNECTION:
-- read uncommitted should maintain no lock on the row.
set connection iso_read_uncommitted;
select * from test_2;

CALL SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY('derby.language.bulkFetchDefault','1');
get cursor scan_cursor as 
    'select a from test_2'; 
call SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY('derby.language.bulkFetchDefault', '16');
next scan_cursor;

-- WRITER CONNECTION:
set connection writer;
-- writer can't do ddl while reader has open cursor (reader blocks writer).
drop table test_2;
-- get lock on test_2, held to end of xact.
insert into test_2 values (2);

-- READ UNCOMMITTED CONNECTION:
-- uncommitted reader is blocked from doing ddl while other xact has locks.
-- (writer blocks reader).
set connection iso_read_uncommitted;
close scan_cursor;
commit;
-- should block on lock (writer blocks reader).
drop table test_2;

-- cleanup
set connection iso_read_uncommitted;
commit;
set connection writer;
commit;
drop table test_2;
commit;

--------------------------------------------------------------------------------
-- FINAL CLEANUP (only disconnect at end of script)
set connection writer;
commit;
disconnect;
set connection iso_read_uncommitted;
commit;
disconnect;