如何从Pl/SQL中的存储函数返回临时CLOB实例? [英] How to return temporary CLOB instance from stored function in Pl/SQL?
问题描述
我的存储函数使用以下方法创建临时LOB实例:Dbms_Lob.CreateTemporary(BUFFER, TRUE, Dbms_Lob.SESSION);
其中,BUFFER
是局部CLOB
变量.之后,该函数用一些数据填充BUFFER
并返回它.
Dbms_Lob.CreateTemporary
的持续时间参数是Dbms_Lob.SESSION
,但根据解决方案在评论中您说:
clob.getSubString(0, clob.length())
引发:java.sql.SQLException: Invalid argument(s) in call at oracle.sql.CLOB.getSubString(CLOB.java:236)
而clob.length()
返回我的Clob的实际长度
The duration parameter passed to dbms_lob.createtemporary() is a hint. The duration of the new temp LOB is the same as the duration of the locator variable in PL/SQL. For example, in the preceding program block, the program variable a has the duration of the residing frame. Therefore at the end of the block, memory of a will be freed at the end of the function.
So BUFFER CLOB
may be destroyed by Oracle after leaving the function block. I can see that in some cases, when the BUFFER is more than 32K, I can’t read it’s value returned this way from Java (JDBC) side.
Is there any other way to return temporary CLOB instance from a function?
In a comment you said:
clob.getSubString(0, clob.length())
throws:java.sql.SQLException: Invalid argument(s) in call at oracle.sql.CLOB.getSubString(CLOB.java:236)
whileclob.length()
returns actual length of my clob
The documentation of getSubString
states that:
pos - the first character of the substring to be extracted. The first character is at position 1.
With a simple function to generate and return a CLOB, I can retrieve it over JDBC (ojdbc5
or ojdbc6
) with no problems, either with getCLOB()
or getString()
. But if I try to assign the Oracle.sql.CLOB
retrieved with getCLOB
to a String
using
String x = getSubString(0, clob.length());
then I also get the Invalid argument(s) in call
error. Just changing that to:
String x = getSubString(1, clob.length());
works. So it seems to have nothing to do with the temporary allocation in the function, or the CLOB size. I don't understand why you didn't have a problem with smaller CLOBs - maybe your logic just didn't hit this if they were small?
In the meantime you've worked around this with clob.getCharacterStream().read()
, so this may be a bit irrelevant now.
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