Processes in v$process that do not exist in v$session (2 node RAC)!

Question

Hi, all.
The database is 2 node RAC database (10.2.0.2.0)
on 32 bit windows 2003 EE SP1.
Our database is suffering "CKPT hang" from time to time.
I checked v$process and v$session on both node by the following sql.
select addr,pid,spid,username, program
from v$process
where addr not in (select paddr from v$session)
ADDR PID SPID USERNAME PROGRAM
56E2 1 PSEUDO
56E2 18 3984 SYSTEM ORACLE.EXE (D000)
56E2 19 4020 SYSTEM ORACLE.EXE (S000)
56E2 27 3176 SYSTEM ORACLE.EXE (PZ99)
56E3 39 2296 SYSTEM ORACLE.EXE (PZ97)
●select * from v$px_process
SERVER_NAME STATUS PID SPID SID SERIAL#
PZ97 AVAILABLE 39 2296
PZ99 AVAILABLE 27 3176
●select * from V$PX_SESSION
--> no rows
●select slave_name,status from v$pq_slave
SLAVE_NAME STATUS
PZ97 IDLE
PZ99 IDLE
I found the above processes which do not exist in v$session.
Is this normal??
Thanks and Regards.

Answer 1

you see nothing in v$session because there is nothing to see ...
the Parallel servers are AVAILABLE , ie no session are running parallel executions (as shown in V$PX_SESSION)
PID is not SID