There are some types with "sys.ku$_" prefix, but is that "ku" abbreviation of something? Just nice to know things :)
That I would like to know :)
oocce
2010-10-11 10:36:03
And btw it's type of sys not system. They are different users.
oocce
2010-10-11 11:27:39
+1
A:
Maybe it stands for "knowledge unit"? In Knowledge Management systems:
a KU is anything worth storing that may help things to be done better in the future: help, best practice guidelines etc.
Anyway I don't have any further ideas about this abbreviation etymology :)
andr
2010-10-11 11:41:42
I also want to use common types and do things with best practices, but I don't want to use anything which looks weird and I don't even know what it stands for. Of course it's easier to write ku$_vcnt than for example something like dbms_utility.varchar2_nested_table_type. But code readability it's better with long name which says directly what it represent.
oocce
2010-10-11 11:48:29
@oocce I fully agree with you, but these "ku$" types and views are not widely used - I suppose - so that is not a common speck in the eye
andr
2010-10-11 12:01:22
+4
A:
My suspicion: They're struct definitions in the Oracle kernel, as the V$ objects are public interfaces to dynamic performance information, the GV$ objects are the cross-instance version of the V$ objects, and the X$ objects are the actual data in the kernel. (Think of them as a linked-list of structs, as that's how a lot of them seem to be implemented. Oracle's doesn't call them, for example, "LRU chains" by accident.)
My opinion: You don't need to know what they are, and you should never ever depend on them, because Oracle can and will changed them without any notification.
Adam Musch
2010-10-11 15:36:46
Is it so that you should never use any objects own by sys? Only using stuff included in internal packages like in dbms_*? We are heavily using views of sys for example. Are Oracle going to change those or are those frozen to ensure backward compatibility?
oocce
2010-10-12 06:12:14
The X$ and KU$ objects are undocumented. The objects owned by sys that are documented (such as the V$ views, described in the Database Reference) can and should be used. Oracle changes those very slowly, adding functionality but never removing it; that's the main reason why LONG remains a supported datatype - it exists in V$ views.
Adam Musch
2010-10-12 13:53:09