Seeing the same session_id used on different nodes alot in RAC 11g

From: Dba DBA <>
Date: Wed, 25 Feb 2015 13:52:41 -0500
Message-ID: <>

Not causing a problem, just curious. I may have just not noticed before. I know that a unique session is SID+serial#.

4 node cluster, but only 2 nodes run this DB (so 2 instances) redhat linux 6


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.

Received on Wed Feb 25 2015 - 19:52:41 CET

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