All Oracle Error Codes
Oracle DBA Forum

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

Reusing UNEXPIRED UNDO blocks

Stephen Barr


When do oracle reuse an unexpired undo block?

We have a situation where there are four datafiles
associated with the UNDO tablespace -

2 from dba_data_files
3 where tablespace_name = 'UNDOTBS1'
4 /

---------- ---
    164 NO
    163 NO
    162 NO
     2 YES

You can see that one of the datafiles is marked as
autoextensible - an oversight by the DBA's.

However, we're seeing transactions fail with
ORA-01562: failed to extend rollback segment number

The strange thing is that we checked just before this
transaction failed and there was tons of room in the
tablespace - why would this occur?

The entry in v$undostat for this time period looks
like this -

BEGIN_TIME             : 04-apr-2006 10:35:03

END_TIME               : 04-apr-2006 10:45:03

UNDOTSN               : 1

UNDOBLKS               : 47115

TXNCOUNT               : 272225

MAXQUERYLEN             : 93649

MAXQUERYID             : frma9q6tqbuwd

MAXCONCURRENCY           : 11

UNXPSTEALCNT            : 8

UNXPBLKRELCNT           : 516

UNXPBLKREUCNT           : 0

EXPSTEALCNT             : 1663

EXPBLKRELCNT            : 279212

EXPBLKREUCNT            : 0

SSOLDERRCNT             : 0

NOSPACEERRCNT           : 2

ACTIVEBLKS             : 105344

UNEXPIREDBLKS           : 4307412

EXPIREDBLKS             : 0


The dba_undo_extents view currently looks like this -

2 from dba_undo_extents
3 group by status
4 /

---------- ---------
    401 EXPIRED

Any ideas?

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