Re: SQL*Net message to client

Some of the information you can infer by looking at the output of the following query:

select view_definition from v$fixed_view_definition where view_name = 'GV$SESSION_WAIT'
/

This gives the definition of (g)v$session_wait in terms of the underlying X$ objects, and shows you the way in which some of the v$ columns are derived by decodes from (particularly) the microsecond wait time.

'Client' in this wait event is simply a session at the far end of an SQL*Net link - i.e. incoming database link or normal end-user/batch connection.

In a normal client/server dialogue, e.g. SQL*Plus running a simple query and fetching lots of rows one at a time, you would expect to see this event coming and going very rapidly (alternating with SQL*Net message from client).

Regards

Jonathan Lewis

http://www.jlcomp.demon.co.uk/faq/ind_faq.html The Co-operative Oracle Users' FAQ

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• Original Message ----- From: "Ray Stell" <stellr_at_cns.vt.edu> To: "Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> Cc: "oracle-l" <oracle-l_at_freelists.org> Sent: Wednesday, November 23, 2005 10:08 PM Subject: Re: SQL*Net message to client

> Let me first give thanks for your help.
>
> If you don't mind teaching me to fish, how could I have ascertained this
> explanation on my own?
>
> Little more can be collected on this event. The impatient dba took the
> sledge hammer approach to the log switch-hung db.
>
> There were no user sessions listed in v$session. The other wait events
> were the log switch and a 220 buffer busy, both waiting for the same
> period of time. Oradocs say the 220 is, "during buffer lookup for a
> CURRENT copy of a buffer we have found the buffer but someone holds it
> in an incompatible mode so we have to wait."
>
> So, I'm curious who this client might have been. There is no knowing
> for certain since the evidence has been destroyed. What are the
> possible "clients?" Seems like a bug, unless client means something
> I don't think it means.
>
>
> On Wed, Nov 23, 2005 at 07:56:01PM -0000, Jonathan Lewis wrote:

>> wait_time=-1 means less than 1 hundredth
>> of a second for 8i, and less than 50 milliseconds
>> for later versions of 9.

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