RE: Base table for v_$session ?
- From: "Mark W. Farnham" <mwf@xxxxxxxx>
- To: <jonathan@xxxxxxxxxxxxxxxxxx>, <tim@xxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
- Date: Mon, 22 Sep 2014 14:54:29 -0400
And if you're diving into this rabbit hole, this is the point where Laurence
Fishburne asks you what color pill you want.
There is some really interesting stuff in the fixed views based on the x$
"table" aka memory structures but they behave differently than the usual
read consistent model for real tables.
Some of it is documented, somewhere, and much of it is unlikely to change
but all of it CAN change. And most (all?) of it is unlatched memory, at
least from the perspective of querying it. (The Oracle program probably has
lots of various memory locks on some bits of it - but that has nothing to do
with your read consistent start of query.)
Usually the views are forward compatible, but the underlying structure of
the x$tables should be considered something Oracle can change at whim and
without notice.
mwf
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Jonathan Lewis
Sent: Monday, September 22, 2014 1:50 PM
To: tim@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx
Subject: RE: Base table for v_$session ?
Thought v$session will be in the fixed view definitions, with a definition
something like:
select * from gv$session where inst_id = (select userenv('instance') from
dual)
you remember that userenv() thing - deprecated about 15 years ago for
sys_context('userenv',{parameter})
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
@jloracle
_____
From: oracle-l-bounce@xxxxxxxxxxxxx [oracle-l-bounce@xxxxxxxxxxxxx] on
behalf of Tim Gorman [tim@xxxxxxxxx]
Sent: 22 September 2014 18:12
To: oracle-l@xxxxxxxxxxxxx
Subject: Re: Base table for v_$session ?
...and you'd want to use V$FIXED_VIEW_DEFINITION to look at the definition
of GV$SESSION, as looking at V$SESSION will make you more frustrated. :-)
On 9/22/14, 10:58, Riyaj Shamsudeen wrote:
Sumit
You can find the definition of fixed views in: v$fixed_view_definition
Cheers
Riyaj Shamsudeen
Principal DBA,
Ora!nternals - http://www.orainternals.com <http://www.orainternals.com/>
- Specialists in Performance, RAC and EBS
Blog: http://orainternals.wordpress.com/
Oracle ACE Director and OakTable member <http://www.oaktable.com/>
Co-author of the books: Expert Oracle Practices
<http://tinyurl.com/book-expert-oracle-practices/> , Pro Oracle SQL,
<http://tinyurl.com/ahpvms8> Expert RAC Practices 12c.
<http://tinyurl.com/expert-rac-12c>
<http://tinyurl.com/book-expert-plsql-practices> Expert PL/SQL practices
On Mon, Sep 22, 2014 at 7:59 AM, sumit Tyagi <dba.tyagisumit@xxxxxxxxx>
wrote:
Hi experts ,
Can you please guide how to find the base table for v_$session . I checked
v$session = SYNONYM v_$session is the view .
I checked the DDL of v_$session view thinking that i can get the base table
from here but no success :out
SQL> select DBMS_METADATA.GET_DDL('VIEW','V_$SESSION','SYS') res from
dba_views where view_name='V_$SESSION';
output:
select columns... ........... from v$session.
Thanks and Regards
Sumit
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