Processes in v$process which do not exist in v$session(help)!!

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.
Message was edited by:
user507290

Answer 1

Hi,
>>I can see incomplete checkpoint message in alert log files.
This message indicates that Oracle wants to reuse a redo log file, but the current checkpoint position is still in that log. In this case, Oracle must wait until the checkpoint position passes that log. In fact, the "checkpoint not complete" messages are generated because the logs are switching so fast that the checkpoint associated with the log switch isn't terminated. Oracle stops processing until the checkpoint completes successfully.
In this case, normally you need to increase the size of the redo logs or add more redo log groups. Take a look on http://www.dbazine.com/oracle/or-articles/foot2
Now, as you said that the current redo size is 2 GB, how frequently redo log switch's occurs in the database ? See the SQL's below:
Log Switching Distribution
select to_char(first_time,'DD/MM/YYYY') day,
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'00',1,0)),'999') "00",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'01',1,0)),'999') "01",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'02',1,0)),'999') "02",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'03',1,0)),'999') "03",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'04',1,0)),'999') "04",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'05',1,0)),'999') "05",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'06',1,0)),'999') "06",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'07',1,0)),'999') "07",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'08',1,0)),'999') "08",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'09',1,0)),'999') "09",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'10',1,0)),'999') "10",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'11',1,0)),'999') "11",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'12',1,0)),'999') "12",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'13',1,0)),'999') "13",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'14',1,0)),'999') "14",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'15',1,0)),'999') "15",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'16',1,0)),'999') "16",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'17',1,0)),'999') "17",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'18',1,0)),'999') "18",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'19',1,0)),'999') "19",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'20',1,0)),'999') "20",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'21',1,0)),'999') "21",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'22',1,0)),'999') "22",
to_char(sum(decode(substr(to_char(first_time,'HH24'),1,2),'23',1,0)),'999') "23",
sum(1) "TOTAL_IN_DAY"
from v$log_history
group by to_char(first_time,'DD/MM/YYYY')
order by to_date(day);
Average Switch Time
select to_char(first_time,'DD/MM/YYYY HH24')||':00:00' "Time",
count(*) "Nbswitch",
trunc(60/count(*),1) "Average switch time(minutes)",
count(*)*rsize "EstimateSize"
from v$log_history, (select sum(bytes/1024/1024)/count(*) rsize from v$log)
group by to_char(first_time,'DD/MM/YYYY HH24'),rsize
order by to_date(to_char(first_time,'DD/MM/YYYY HH24'), 'DD/MM/YYYY
HH24')desc;In addition, If you have access on Oracle Metalink, see the Note:147468.1 about Checkpoint Tuning and Troubleshooting Guide.
Cheers