Re: Seeing the same session_id used on different nodes alot in RAC 11g
- From: Rodrigo Mufalani <rodrigo@xxxxxxxxxxxxxxx>
- To: "oracledbaquestions@xxxxxxxxx" <oracledbaquestions@xxxxxxxxx>
- Date: Wed, 25 Feb 2015 16:00:32 -0300
You must put inst_id on your query to identify uniquely the sessions. Yes,
SID numbers are reutilized frequently and serial# is a kind of counter of how
many times that Sid are used since instance startup.
[ ]'s
#mufalani
Desculpe por erros! Este e-mail foi escrito do meu smartphone!
Sorry for typos! This mail was written from my smartphone!!!
> On 25/02/2015, at 15:52, Dba DBA <oracledbaquestions@xxxxxxxxx> wrote:
>
> Not causing a problem, just curious. I may have just not noticed before. I
> know that a unique session is SID+serial#.
>
> Oracle 11.2.0.2
> 4 node cluster, but only 2 nodes run this DB (so 2 instances)
> redhat linux 6
>
> Noticing
>
> select sid,username,count(*) from gv$session group by sid,username having
> count(*) > 1
> seeing this for alot of sessions. Not all. both user sessions and background
> process.
>
> This may be common and I never noticed it. Is it common? Also, I have been
> killing alot of blocking lock sessions for developers lately (due to code
> issues) and then I see the same sessions reused when the application
> reconnects.
>
> How does Oracle pick a session_id ? Does anyone know why we have sid+serial#
> and not just 1 field with enough values ? PART of it might be to support TAF,
> but I have not used that feature so not sure if it uses the same SID.
>
>
> We are not using TAF. Per document below I would see the multiple VIPs on the
> same host. I dont see that in crs_stat.
>
> http://gavinsoorma.com/2009/08/11g-rac-transparent-application-failover-taf/
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