There is AST terminology in oracle, alongside BAST. However, it might be
possible the naming for the x$ tables might come from the oracle layered
naming, where ksa means kernel service asynchronous messages. Also, this table
is used in functions that are in these layers. So that’s why I named them this
Verstuurd vanaf mijn iPad
Op 15 apr. 2018 om 22:49 heeft Mladen Gogala <gogala.mladen@xxxxxxxxx> het--
I believe that it's "kernel service asynchronous system trap". If you
remember Steve Adams internals book, Steve was talking about "blocking AST"
and "non-blocking AST" entities, without explaining what those entities
were. Having been a VAX/VMS system administrator for years, I know those
terms very well. Now, Oracle has preserved its VAX/VMS roots to this day, not
only in "AFIEDT.BUF" files but also in terminology. AST or "asynchronous
system trap" was a very sophisticated mechanism through which an external
code could be executed within the process context. There was AST interrupt
and an associated register in the NVAX family of processors. As opposed to
Intel-like CPU family which only has two CPU modes (kernel and user), NVAX
family of processors had 4 (user, supervisor, executive and kernel). Each
"change mode" instruction was a privileged system trap and, if my memory
serves me right, AST was running as an exec mode code. File system, called
"Files-11" was also running in Exec mode. Steve has never made any attempt
to clarify how AST can be used in a Unix context and a later discussion with
Howard Rogers of the "Dizwell" fame partly explained why.
However, all these notions were completely strange and unfamiliar to the Unix
administrators because Unix had no such thing as AST and still doesn't have
anything like that. Unix signals are nothing like AST because no external
code can be delivered. However, Oracle has developed a sophisticated
emulation, based on sockets. and I believe that x$ksast keeps track of those
"Unix AST" thingies, whatever they might be. Once again, this is only an
assumption. I have not had any confirmation for that assumption.
For those who don't know, "AFIEDT.BUF" comes from Oracle v4 on VAX/VMS. The
"AFI" was "A Friendly Interface" tool, a precursor to sqlplus, and EDT was
VAX/VMS screen editor. There was a wide variety of "sqlplus" competing tools:
sqldba (V6, V7), svrmgrl (V8) and the latest one is sqlcl, which is currently
my favourite. There was a new 18.1 release on the last Thursday, 04/12/2018.
I tested it against Oracle 11.2, Oracle 12.1 and Oracle 12.2 and it works
like a charm.
On 04/15/2018 08:54 AM, Frits Hoogland wrote:
There is some sort of administration kept in x$ksast (kernel service
asynchronous messages state?)
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