我有大量的Oracle函数,用于计算6个表中的数据。
create or replace FUNCTION STATISTICS_FUNCTION(NAMEIN IN VARCHAR2
)
RETURN CLOB
AS
LAST_60_CPU NUMBER;
.............
LINE CLOB;
CURSOR LAST_60_CPU_CURSOR IS
.................
BEGIN
LINE := EMPTY_CLOB();
DBMS_LOB.CREATETEMPORARY(LINE,true);
OPEN LAST_60_CPU_CURSOR;
LOOP
FETCH LAST_60_CPU_CURSOR INTO LAST_60_EVENT_DATE, LAST_60_CPU;
....................
DBMS_LOB.APPEND(LINE, TO_CHAR(LAST_60_EVENT_DATE));
DBMS_LOB.APPEND(LINE, 'I');
DBMS_LOB.APPEND(LINE, TO_CHAR(LAST_60_CPU));
DBMS_LOB.APPEND(LINE, CHR(10));
END LOOP;
CLOSE LAST_60_CPU_CURSOR;
DBMS_LOB.APPEND(LINE, 'LAST_60_CPU');
DBMS_LOB.APPEND(LINE, CHR(10));
.......................................................
-------------------------------------
DBMS_OUTPUT.PUT_LINE(LINE);
RETURN LINE;
END STATISTICS_FUNCTION;
我使用这个Java代码来调用函数:
public void callFunction() throws SQLException
{
// initialize the driver and try to make a connection
DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe", "admin", "qwerty");
// prepareCall uses ANSI92 "call" syntax
CallableStatement cstmt = conn.prepareCall("{? = call AGENT_STATISTICS_FUNCTION(?)}");
// get those bind variables and parameters set up
cstmt.registerOutParameter(1, Types.VARCHAR);
cstmt.setString(2, "agent");
// now we can do it, get it, close it, and print it
cstmt.execute();
String result = cstmt.getString(1);
conn.close();
System.out.println(result);
}
我厌倦了在没有这一行的情况下调用函数:
DBMS_LOB.CREATETEMPORARY(LINE,true);
但我得到错误:
Connecting to the database local.
ORA-22275: invalid LOB locator specified
ORA-06512: at "SYS.DBMS_LOB", line 639
ORA-06512: at "ADMIN.STATISTICS_FUNCTION", line 596
ORA-06512: at line 7
Process exited.
Disconnecting from the database local.
如果没有DBMS_LOB.CREATETEMPORARY(LINE,true),你知道为什么我会收到这个错误;?
答案 0 :(得分:5)
你知道为什么我在没有
DBMS_LOB.CREATETEMPORARY(LINE,true);
的情况下出现这个错误吗?
是。 LOB是指向内存/磁盘存储的指针/引用。你需要" memalloc()" (...初始化)存储首先,将指针/引用分配给您的LOB变量。这是dbms_lob.createTemporary()
的用途。除非使用有效的LOB定位器初始化LOB变量,否则对该LOB变量的所有操作都将失败并显示ORA-22275: invalid LOB locator specified
。
增强功能:让您的PL / SQL函数重构一下:
(请注意,我对last_60_cpu_cursor
游标使用了一个虚拟查询。不要重复使用光标,使用自己的游标!: - ))
create or replace
function statistics_function
( namein in varchar2 )
return clob
is
line clob;
cursor last_60_cpu_cursor is
select 1 as last_60_cpu, sysdate as last_60_event_date
from dual
;
begin
dbms_lob.createtemporary(lob_loc => line, cache => true, dur => dbms_lob.call);
for cv in last_60_cpu_cursor loop
dbms_lob.append(line, to_char(cv.last_60_event_date)||'i'||to_char(cv.last_60_cpu)||chr(10));
end loop;
dbms_lob.append(line, 'last_60_cpu'||chr(10));
return line;
end statistics_function;
cache => true
;正如您已经拥有的那样)。这可以确保将数据块添加到内存中的LOB,而不是添加到磁盘上(cache => false
)。dbms_lob.append()
的调用次数。dbms_output.put_line()
。如果LOB内容大于32K,无论如何都会抛出异常。此外,在您完成将LOB交付给Java环境free the temporary LOB之后。 (我不是Java人,不能自己编写Java代码片段。)
此外,您的Java代码中存在概念错误;将函数的返回值注册为Types.VARCHAR
是错误的。你应该使用Oracle's dedicated CLOB type。 (我已经看过C#中的那些,Java也必须拥有它们。)
此外,您的解决方案存在一个性能问题。您的函数返回LOB。在PL / SQL中,每个函数值作为内部值的深层副本返回给其调用者。因此,如果从函数返回LOB,则LOB内容将在后台与新的LOB定位符(/ pointer / reference)重复。您应该使用您可以考虑使用存储过程而不是函数,并将LOB作为out nocopy
参数传递给Java。存储过程将如下所示:
create or replace
procedure statistics_function
( namein in varchar2
, lob_out out nocopy clob )
is
cursor last_60_cpu_cursor is
select 1 as last_60_cpu, sysdate as last_60_event_date
from dual
;
begin
dbms_lob.createtemporary(lob_loc => lob_out, cache => true, dur => dbms_lob.session);
for cv in last_60_cpu_cursor loop
dbms_lob.append(lob_out, to_char(cv.last_60_event_date)||'i'||to_char(cv.last_60_cpu)||chr(10));
end loop;
dbms_lob.append(lob_out, 'last_60_cpu'||chr(10)||chr(10));
end statistics_function;
您的Java调用看起来如何,取决于您和JDBC doc;但是,当然,以这种方式返回的LOB意味着没有复制背景内容。当然,释放分配的临时LOB的需要仍然适用。
答案 1 :(得分:2)
CLOB类似于文件句柄。因此,Oracle有时称它为lob定位器。它必须指向表的数据段(lob段)或临时表空间。 LOB最多可以达到176TB,因此它们不能保存在数据库服务器RAM中,也不能保存在Java JVM堆中。
有时从/到VARCHAR2的隐式转换有效,所以看起来CLOB可能像其他任何变量一样。你总是应该用超过32KB的文本检查CLOB代码。
PS:你还应该在正确的地方明确地调用freetemporary()。 Java GC不与数据库引擎通信,因此数据库不知道何时可以释放TEMP空间。
UPDATE1:处理来自被调用程序的数据后,您应该调用oracle.sql.CLOB.freetemporary()
或java.sql.BLOB.free
或BEGIN DBMS_LOB.CREATETEMPORARY(:CLOB,true); END;
。你也可以在每次调用时重复使用定位器(除非你在连接上使用commit)。我记得在使用JDBC API释放通过PL / SQL分配的LOB定位器时遇到了一些问题。
UPDATE2:您可能需要DBA privs并且还可以访问db server来启动会话跟踪。要启动和停止会话跟踪,请执行:
exec dbms_monitor.session_trace_enable(session_id=>X,serial_num=>Y,binds=>true,waits=>true);
exec dbms_monitor.session_trace_disable(session_id=>X,serial_num=>Y);
其中X和Y是来自v $ session视图的会话标识符SID和SERIAL#。
这是在创建大小为65KB的临时lob并且参数缓存设置为false
时会话跟踪的样子:
WAIT #0: nam='Disk file operations I/O' ela= 277 FileOperation=2 fileno=201 filetype=2 obj#=-1 tim=1448362135289035
LOBTMPCREATE: c=1000,e=689,p=0,cr=0,cu=2,tim=1448362135289171
WAIT #0: nam='SQL*Net message to client' ela= 2 driver id=1413697536 #bytes=1 p3=0 obj#=-1 tim=1448362135289218
WAIT #0: nam='SQL*Net message from client' ela= 2594 driver id=1413697536 #bytes=1 p3=0 obj#=-1 tim=1448362135291842
WAIT #0: nam='SQL*Net more data from client' ela= 20 driver id=1413697536 #bytes=32 p3=0 obj#=-1 tim=1448362135292339
WAIT #0: nam='SQL*Net more data from client' ela= 796 driver id=1413697536 #bytes=83 p3=0 obj#=-1 tim=1448362135293233
WAIT #0: nam='SQL*Net more data from client' ela= 18 driver id=1413697536 #bytes=65 p3=0 obj#=-1 tim=1448362135293361
WAIT #0: nam='SQL*Net more data from client' ela= 16 driver id=1413697536 #bytes=27 p3=0 obj#=-1 tim=1448362135293449
WAIT #0: nam='SQL*Net more data from client' ela= 749 driver id=1413697536 #bytes=30 p3=0 obj#=-1 tim=1448362135294243
WAIT #0: nam='SQL*Net more data from client' ela= 301 driver id=1413697536 #bytes=12 p3=0 obj#=-1 tim=1448362135294623
WAIT #0: nam='SQL*Net more data from client' ela= 35 driver id=1413697536 #bytes=22 p3=0 obj#=-1 tim=1448362135294786
WAIT #0: nam='SQL*Net more data from client' ela= 16 driver id=1413697536 #bytes=189 p3=0 obj#=-1 tim=1448362135294866
WAIT #0: nam='SQL*Net more data from client' ela= 10 driver id=1413697536 #bytes=103 p3=0 obj#=-1 tim=1448362135294913
WAIT #0: nam='SQL*Net more data from client' ela= 9 driver id=1413697536 #bytes=17 p3=0 obj#=-1 tim=1448362135294955
WAIT #0: nam='SQL*Net more data from client' ela= 697 driver id=1413697536 #bytes=184 p3=0 obj#=-1 tim=1448362135295685
WAIT #0: nam='SQL*Net more data from client' ela= 16 driver id=1413697536 #bytes=98 p3=0 obj#=-1 tim=1448362135295801
WAIT #0: nam='SQL*Net more data from client' ela= 21 driver id=1413697536 #bytes=12 p3=0 obj#=-1 tim=1448362135296189
WAIT #0: nam='SQL*Net more data from client' ela= 12 driver id=1413697536 #bytes=179 p3=0 obj#=-1 tim=1448362135296274
WAIT #0: nam='SQL*Net more data from client' ela= 10 driver id=1413697536 #bytes=93 p3=0 obj#=-1 tim=1448362135296344
WAIT #0: nam='CSS initialization' ela= 7307 p1=0 p2=0 p3=0 obj#=-1 tim=1448362135303779
WAIT #0: nam='CSS operation: action' ela= 2479 function_id=65 p2=0 p3=0 obj#=-1 tim=1448362135306327
WAIT #0: nam='Disk file operations I/O' ela= 823 FileOperation=2 fileno=0 filetype=15 obj#=-1 tim=1448362135307307
WAIT #0: nam='CSS initialization' ela= 22 p1=0 p2=0 p3=0 obj#=-1 tim=1448362135307865
WAIT #0: nam='CSS operation: query' ela= 5 function_id=42 p2=0 p3=0 obj#=-1 tim=1448362135307914
WAIT #0: nam='CSS operation: query' ela= 1 function_id=42 p2=0 p3=0 obj#=-1 tim=1448362135307932
WAIT #0: nam='CSS operation: query' ela= 1 function_id=42 p2=0 p3=0 obj#=-1 tim=1448362135307947
WAIT #0: nam='CSS operation: query' ela= 1 function_id=42 p2=0 p3=0 obj#=-1 tim=1448362135307963
WAIT #0: nam='CSS operation: query' ela= 6 function_id=33 p2=0 p3=0 obj#=-1 tim=1448362135307986
WAIT #0: nam='CSS operation: query' ela= 612 function_id=39 p2=0 p3=0 obj#=-1 tim=1448362135308625
WAIT #0: nam='CSS operation: action' ela= 2589 function_id=65 p2=0 p3=0 obj#=-1 tim=1448362135311258
WAIT #0: nam='direct path write temp' ela= 1373 file number=201 first dba=927747 block cnt=16 obj#=-1 tim=1448362135313337
LOBWRITE: c=9998,e=21487,p=0,cr=0,cu=61,tim=1448362135313441
WAIT #0: nam='SQL*Net message to client' ela= 3 driver id=1413697536 #bytes=1 p3=0 obj#=-1 tim=1448362135313499
WAIT #0: nam='SQL*Net message from client' ela= 3187 driver id=1413697536 #bytes=1 p3=0 obj#=-1 tim=1448362135316722
如您所见,它包含直接路径写入临时表空间。
这是使用缓存设置为true
时的样子。
WAIT #0: nam='Disk file operations I/O' ela= 267 FileOperation=2 fileno=201 filetype=2 obj#=-1 tim=1448363565002340
LOBTMPCREATE: c=0,e=650,p=0,cr=0,cu=2,tim=1448363565002469
WAIT #0: nam='SQL*Net message to client' ela= 2 driver id=1413697536 #bytes=1 p3=0 obj#=-1 tim=1448363565002515
WAIT #0: nam='SQL*Net message from client' ela= 2424 driver id=1413697536 #bytes=1 p3=0 obj#=-1 tim=1448363565004970
WAIT #0: nam='SQL*Net more data from client' ela= 17 driver id=1413697536 #bytes=32 p3=0 obj#=-1 tim=1448363565005390
WAIT #0: nam='SQL*Net more data from client' ela= 975 driver id=1413697536 #bytes=83 p3=0 obj#=-1 tim=1448363565006434
WAIT #0: nam='SQL*Net more data from client' ela= 21 driver id=1413697536 #bytes=65 p3=0 obj#=-1 tim=1448363565006545
WAIT #0: nam='SQL*Net more data from client' ela= 621 driver id=1413697536 #bytes=27 p3=0 obj#=-1 tim=1448363565007210
WAIT #0: nam='SQL*Net more data from client' ela= 337 driver id=1413697536 #bytes=30 p3=0 obj#=-1 tim=1448363565007648
WAIT #0: nam='SQL*Net more data from client' ela= 20 driver id=1413697536 #bytes=12 p3=0 obj#=-1 tim=1448363565007795
WAIT #0: nam='SQL*Net more data from client' ela= 18 driver id=1413697536 #bytes=22 p3=0 obj#=-1 tim=1448363565007925
WAIT #0: nam='SQL*Net more data from client' ela= 10 driver id=1413697536 #bytes=189 p3=0 obj#=-1 tim=1448363565007983
WAIT #0: nam='SQL*Net more data from client' ela= 555 driver id=1413697536 #bytes=103 p3=0 obj#=-1 tim=1448363565008576
WAIT #0: nam='SQL*Net more data from client' ela= 21 driver id=1413697536 #bytes=17 p3=0 obj#=-1 tim=1448363565008749
WAIT #0: nam='SQL*Net more data from client' ela= 10 driver id=1413697536 #bytes=184 p3=0 obj#=-1 tim=1448363565008811
WAIT #0: nam='SQL*Net more data from client' ela= 176 driver id=1413697536 #bytes=98 p3=0 obj#=-1 tim=1448363565009038
WAIT #0: nam='SQL*Net more data from client' ela= 23 driver id=1413697536 #bytes=12 p3=0 obj#=-1 tim=1448363565009438
WAIT #0: nam='SQL*Net more data from client' ela= 12 driver id=1413697536 #bytes=179 p3=0 obj#=-1 tim=1448363565009525
WAIT #0: nam='SQL*Net more data from client' ela= 12 driver id=1413697536 #bytes=93 p3=0 obj#=-1 tim=1448363565009607
LOBWRITE: c=3000,e=4660,p=0,cr=0,cu=61,tim=1448363565009692
WAIT #0: nam='SQL*Net message to client' ela= 2 driver id=1413697536 #bytes=1 p3=0 obj#=-1 tim=1448363565009738
WAIT #0: nam='SQL*Net message from client' ela= 3308 driver id=1413697536 #bytes=1 p3=0 obj#=-1 tim=1448363565013077