oracle管道函数是一类特殊的函数,oracle管道函数返回值类型必须为集合,下面就为您将介绍oracle管道函数的语法,供您参考学习。
在普通的函数中,使用dbms_output输出的信息,需要在服务器执行完整个函数后一次性的返回给客户端。如果需要在客户端实时的输出函数执行过程中的一些信息,在oracle9i以后可以使用管道函数(pipeline function)。
关键字PIPELINED表明这是一个oracle管道函数,oracle管道函数的返回值类型必须为集合,在函数中,PIPE ROW语句被用来返回该集合的单个元素,函数以一个空的RETURN 语句结束,以表明它已经完成。
create or replace type MsgType as table of varchar2(4000);
/
create or replace function f_pipeline_test
return MsgType
PIPELINED
as
begin
for i in 1 .. 10
loop
pipe row( 'Iteration ' || i || ' at ' || systimestamp );
dbms_lock.sleep(1);
end loop;
pipe row( 'All done!' );
return;
end;
/
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在sql*plus中执行该函数,首先设置arraysize为1,否则服务器会按照默认的15来向客户端返回信息,这会影响我们的测试效果。
SQL> set arraysize 1
SQL> select * from table( f_pipeline_test );
COLUMN_VALUE
--------------------------------------------------------------------------------
Iteration 1 at 14-FEB-08 02.13.18.273988000 PM +08:00
Iteration 2 at 14-FEB-08 02.13.19.275988000 PM +08:00
Iteration 3 at 14-FEB-08 02.13.20.277767000 PM +08:00
Iteration 4 at 14-FEB-08 02.13.21.279591000 PM +08:00
Iteration 5 at 14-FEB-08 02.13.22.281366000 PM +08:00
Iteration 6 at 14-FEB-08 02.13.23.283189000 PM +08:00
Iteration 7 at 14-FEB-08 02.13.24.283965000 PM +08:00
Iteration 8 at 14-FEB-08 02.13.25.285785000 PM +08:00
Iteration 9 at 14-FEB-08 02.13.26.286570000 PM +08:00
Iteration 10 at 14-FEB-08 02.13.27.288387000 PM +08:00
All done!
11 rows selected.
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如果要在pipeline中执行DML操作,则必须使用自治事务,否则会报ORA-14551错误
create or replace function f_pipeline_testdml
return MsgType
PIPELINED
as
begin
for i in 1 .. 10
loop
insert into test values(1);
pipe row( 'insert into test values( ' || i || ') success at ' || systimestamp );
dbms_lock.sleep(1);
end loop;
pipe row( 'All done!' );
return;
end;
/
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SQL> select * from table( f_pipeline_testdml );
select * from table( f_pipeline_testdml )
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*
ERROR at line 1:
ORA-14551: cannot perform a DML operation inside a query
ORA-06512: at "NING.F_PIPELINE_TESTDML", line 8create or replace function f_pipeline_testdml
return MsgType
PIPELINED
as
pragma autonomous_transaction;
begin
for i in 1 .. 10
loop
insert into test values(1);
commit;
pipe row( 'insert values ' || i || ' success at ' || systimestamp );
dbms_lock.sleep(1);
end loop;
pipe row( 'All done!' );
return;
end;
/
SQL> select * from table( f_pipeline_testdml );
COLUMN_VALUE
--------------------------------------------------------------------------------
insert values 1 success at 14-FEB-08 02.16.47.855158000 PM +08:00
insert values 2 success at 14-FEB-08 02.16.48.865559000 PM +08:00
insert values 3 success at 14-FEB-08 02.16.49.867377000 PM +08:00
insert values 4 success at 14-FEB-08 02.16.50.873154000 PM +08:00
insert values 5 success at 14-FEB-08 02.16.51.874942000 PM +08:00
insert values 6 success at 14-FEB-08 02.16.52.880781000 PM +08:00
insert values 7 success at 14-FEB-08 02.16.53.882543000 PM +08:00
insert values 8 success at 14-FEB-08 02.16.54.894348000 PM +08:00
insert values 9 success at 14-FEB-08 02.16.55.896153000 PM +08:00
insert values 10 success at 14-FEB-08 02.16.56.901904000 PM +08:00
All done!
11 rows selected.
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在oracle9205及其之后的版本中,在pipeline function中使用自治事务,则必须在pipe row之前提交或者回滚事务,否则会报ORA-06519错误
create or replace function f_pipeline_testdml
return MsgType
PIPELINED
as
pragma autonomous_transaction;
begin
for i in 1 .. 10
loop
insert into test values(1);
pipe row( 'insert values ' || i || ' success at ' || systimestamp );
dbms_lock.sleep(1);
end loop;
pipe row( 'All done!' );
commit;
return;
end;
/
SQL> select * from table( f_pipeline_testdml );
select * from table( f_pipeline_testdml )
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*
ERROR at line 1:
ORA-06519: active autonomous transaction detected and rolled back
ORA-06512: at "NING.F_PIPELINE_TESTDML", line 10
这是由于在9205中修复Bug 2711518导致了自治事务的行为有所改变。如果系统从9205之前的版本 升级到之后的版本,需要保证pipeline function的行为和以前版本一致,oracle提供了一个10946事件来设置和以前版本的兼容性,如果在管道函数中使用了select for update的cursor,则必须设置event回归以前的特性,否则即使在pipe row之前commit也会导致ORA-1002错误。
ALTER SYSTEM SET EVENT = "10946 trace name context forever, level 8" scope=spfile;
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