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Frequent Oracle Errors

TNS:could not resolve the connect identifier specified
Backtrace message unwound by exceptions
invalid identifier
PL/SQL compilation error
internal error
missing expression
table or view does not exist
end-of-file on communication channel
TNS:listener unknown in connect descriptor
insufficient privileges
PL/SQL: numeric or value error string
TNS:protocol adapter error
ORACLE not available
target host or object does not exist
invalid number
unable to allocate string bytes of shared memory
resource busy and acquire with NOWAIT specified
error occurred at recursive SQL level string
ORACLE initialization or shutdown in progress
archiver error. Connect internal only, until freed
snapshot too old
unable to extend temp segment by string in tablespace
Credential retrieval failed
missing or invalid option
invalid username/password; logon denied
unable to create INITIAL extent for segment
out of process memory when trying to allocate string bytes
shared memory realm does not exist
cannot insert NULL
TNS:unable to connect to destination
remote database not found ora-02019
exception encountered: core dump
inconsistent datatypes
no data found
TNS:operation timed out
PL/SQL: could not find program
existing state of packages has been discarded
maximum number of processes exceeded
error signaled in parallel query server
ORACLE instance terminated. Disconnection forced
TNS:packet writer failure
see ORA-12699
missing right parenthesis
name is already used by an existing object
cannot identify/lock data file
invalid file operation
quoted string not properly terminated

CPU priority for AIX 5.3 with mixed workload

Adrian Turner



My customer is running a database on AIX5.3, p590 with 14 Power 5
CPUs and SMT enabled.

The day workload is 8000 dedicated user connections plus 5 or so concurrent
long running reports.

They have an overnight batch job that is CPU bound and taking 8+ hours to

On an unladen identical test system the same batch job completes in 2.5

Lets put aside wait events and tracing for now as I know how to measure and
factor those.


"On the AIX 5L operating system, the default scheduling policy is fair round
robin, also referenced as SCHED_OTHER. This policy implements a classic
priority queue round-robin algorithm with one major difference: the priority
is no longer fixed. This means, for example, if a task is using a large
amount of processor time, its priority level is slowly downgraded to give
other jobs an opportunity to gain access to the processor. The drawback of
this approach is that sometimes a process can end up with a priority level
so low that it does not have an opportunity to run and finish. By default, a
process receives a base priority of 40 and a default nice value of 20.
Combined, these two values define the default priority of a process (for
example, 60). However, a process can carry a priority ranging between 0 to
255, where priority 0 is the highest and 255 is the lowest (least favorable
for the purposes of gaining access to a processor)"

I've noticed that the CPU priority for the batch job is a lowly 90-120 for
most of the run.

Q1. Is there any way of measuring the impact of this on the job?

Q2 I am after experiences in changing the default priority for an AIX5L
database with (or without) this kind of mixed workload. Good or bad

Thanks in advance,