dbms_parallel_execute.create_task(task_name => vc_task); --手工定义一个Task任务；
--Define the Spilt
dbms_parallel_execute.create_chunks_by_rowid(task_name => vc_task,
table_owner => 'SYS',
table_name => 'T',
by_row => true,
chunk_size => 1000); --定义Chunk
vc_sql := 'update /*+ ROWID(dda) */t set DATA_OBJECT_ID=object_id+1 where rowid between :start_id and :end_id';
--Run the task
dbms_parallel_execute.run_task(task_name => vc_task,
sql_stmt => vc_sql,
language_flag => dbms_sql.native,
parallel_level => 2); --执行任务，确定并行度
--Controller
n_try := 0;
n_status := dbms_parallel_execute.task_status(task_name => vc_task);
while (n_try<2 and n_status != dbms_parallel_execute.FINISHED) loop
dbms_parallel_execute.resume_task(task_name => vc_task);
n_status := dbms_parallel_execute.task_status(task_name => vc_task);
end loop;
--Deal with Result
dbms_parallel_execute.drop_task(task_name => vc_task);
end;
/
从调用过程来看，这个并行操作包括下面几个步骤：
ü 定义Task；
ü 确定chunk划分方法，定义每个chunk的范围信息；
ü 执行作业，确定并行作业进程数量；
这个调用过程和我们常见的并行方式有很大差异，类似于Oracle的Job Schedule机制。由于执行过程比较长，我们可以有比较从容的查看并行执行包的情况。
从user_parallel_execute_tasks中，看到当前作业的关键信息。注意：chunk_type表示的是采用什么样的划分方法。JOB_PREFIX对应的则是Schedule中的内容。
SQL> select task_name, chunk_type, JOB_PREFIX from user_parallel_execute_tasks;
TASK_NAME CHUNK_TYPE JOB_PREFIX
-------------------- ------------ ------------------------------
Task 1: By Rowid ROWID_RANGE TASK$_4
在user_parallel_execute_chunks中，作业的所有chunk划分，每个chunk对应的一行数据。其中包括这个chunk的起始和截止rowid。对应的chunk取值对应的就是每个chunk的数据行数。
SQL> select chunk_id, task_name, status, start_rowid, end_rowid from user_parallel_execute_chunks where rownum<10;
CHUNK_ID TASK_NAME STATUS START_ROWID END_ROWID
---------- -------------------- -------------------- ------------------ ------------------
1 Task 1: By Rowid PROCESSED AAATLKAAHAAAACAAAA AAATLKAAHAAAACxCcP
2 Task 1: By Rowid PROCESSED AAATLKAAHAAAACyAAA AAATLKAAHAAAADjCcP
3 Task 1: By Rowid PROCESSED AAATLKAAHAAAADkAAA AAATLKAAHAAAAD/CcP
4 Task 1: By Rowid PROCESSED AAATLKAAHAAAAEAAAA AAATLKAAHAAAAExCcP
5 Task 1: By Rowid PROCESSED AAATLKAAHAAAAEyAAA AAATLKAAHAAAAFjCcP
6 Task 1: By Rowid PROCESSED AAATLKAAHAAAAFkAAA AAATLKAAHAAAAF/CcP
7 Task 1: By Rowid PROCESSED AAATLKAAHAAAAGAAAA AAATLKAAHAAAAGxCcP
8 Task 1: By Rowid PROCESSED AAATLKAAHAAAAGyAAA AAATLKAAHAAAAHjCcP
9 Task 1: By Rowid PROCESSED AAATLKAAHAAAAHkAAA AAATLKAAHAAAAH/CcP
9 rows selected
作为user_parallel_execute_chunks，一个很重要的字段就是status状态列，用于标注每个chunk的处理情况。我们可以依据这个字段来判断任务完成情况。
SQL> select status, count(*) from user_parallel_execute_chunks group by status;
STATUS COUNT(*)
-------------------- ----------
ASSIGNED 2
UNASSIGNED 5507
PROCESSED 938
（过一会之后…….）
SQL> select status, count(*) from user_parallel_execute_chunks group by status;
STATUS COUNT(*)
-------------------- ----------
ASSIGNED 2
UNASSIGNED 5441
PROCESSED 1004
从status字段，我们可以分析出并行作业工作的原理。每一个chunk记录在划分之后，都是设置为unassig