ORADEBUG – UNDOCUMENTED ORACLE UTILITY
By
Miladin Modrakovic
rankoni@hotmail.com
Introduction
This document describes Oracle utility called oradebug. This tool is primarily used by Oracle
worldwide customer support .With oradebug utility you can literally see the database engine. The
oradebug is especially useful when things go very bad – e.g. the database just stops, hangs, or the
database keeps crashing with the ORA-0600 error! To run this tool you must have administrator
privileges.
Among the many useful things that can be done with oradebug are:
– enabling/disabling the SQL tracing for another user’s session.
– suspending intensive processes
– finding information about shared memory and semaphores
– closing the trace file so that new one can be generated
– manipulating and dumping internal structures
– wake up processes etc.
Oradebug Commands
The oradebug utility consists of the following commands:
HELP [command] Describe one or all commands
SETMYPID Debug current process
SETOSPID <ospid> Set OS pid of process to debug
SETORAPID <orapid> [‘force’] Set Oracle pid of process to debug
DUMP <dump_name> <lvl> [addr] Invoke named dump
DUMPSGA [bytes] Dump fixed SGA
DUMPLIST Print a list of available dumps
EVENT <text> Set trace event in process
SESSION_EVENT <text> Set trace event in session
DUMPVAR <p|s|uga> <name> [level] Print/dump a fixed PGA/SGA/UGA variable
SETVAR <p|s|uga> <name> <value> Modify a fixed PGA/SGA/UGA variable
PEEK <addr> <len> [level] Print/Dump memory
POKE <addr> <len> <value> Modify memory
WAKEUP <orapid> Wake up Oracle process
SUSPEND Suspend execution
RESUME Resume execution
FLUSH Flush pending writes to trace file
CLOSE_TRACE Close trace file
TRACEFILE_NAME Get name of trace file
LKDEBUG Invoke global enqueue service debugger
NSDBX Invoke CGS name-service debugger
-G <Inst-List | def | all> Parallel oradebug command prefix
-R <Inst-List | def | all> Parallel oradebug prefix (return output
SETINST <instance# .. | all> Set instance list in double quotes
SGATOFILE <SGA dump dir> Dump SGA to file; dirname in double quotes
DMPCOWSGA <SGA dump dir> Dump & map SGA as COW; dirname in double quotes
MAPCOWSGA <SGA dump dir> Map SGA as COW; dirname in double quotes
HANGANALYZE [level] Analyze system hang
FFBEGIN Flash Freeze the Instance
FFDEREGISTER FF deregister instance from cluster
FFTERMINST Call exit and terminate instance
FFRESUMEINST Resume the flash frozen instance
FFSTATUS Flash freeze status of instance
SKDSTTPCS <ifname> <ofname> Helps translate PCs to names
WATCH <address> <len> <self|exist|all|target> Watch a region of memory
DELETE <local|global|target> watchpoint <id> Delete a watchpoint
SHOW <local|global|target> watchpoints Show watchpoints
CORE Dump core without crashing process
IPC Dump ipc information
UNLIMIT Unlimit the size of the trace file
PROCSTAT Dump process statistics
CALL <func> [arg1] … [argn] Invoke function with arguments
oradebug help
Describe one or all debug commands available for use.
Syntax Parameter
oradebug help < command name > <command name > name of the debug command
If left alone oradebug help will list all debug commands.
Example
SQL> oradebug help show
SHOW <local|global|target> watchpoints Show watchpoints
oradebug setmypid
Debug current process.
Syntax Parameter
oradebug setmypid None
oradebug setospid
Set OS process id of process to debug.
Syntax Parameter
oradebug setospid <ospid> <ospid> OS PID to attach
Example
select spid, pid
from v$process
where addr = (select paddr from v$session where sid = <your SID >);
SQL> oradebug setospid 19592
Oracle pid: 18, Unix process pid: 19592, image: oracle@apollo(TNS V1-V3)
oradebug setorapid
Set Oracle pid of process to debug.
Syntax Parameter(s)
oradebug setorapid <orapid> [‘force’] <orapid> Oracle PID
[‘force’] Force process
Example
SQL> oradebug setorapid 18 (use pid from the query above)
Unix process pid: 19592, image: oracle@apollo (TNS V1-V3) or using force option
SQL> oradebug setorapid 18 force
Statement processed.
oradebug dump commands are explained in ORADEBUG DUMPS a special chapter of this
paper dedicated to a various oracle dumps.
oradebug event
Set trace event in process.
Syntax Parameter
oradebug event <text> <text> Event name
Event numbers can be found in $ORACLE_HOME/rdbms/mesg/oraus.msg
or on the address below:
http://www.kevinloney.com/free/events.htm
Example
In this example I have used event event 10046 which is probably the most used event.
To enable tracing for another session, the Oracle (PID) or the OS PID (SPID) must be
identified from v$process view.
SQLPLUS> oradebug setospid 10929
Oracle pid: 91, Unix process pid: 10929, image: oracleorcl
SQLPLUS> oradebug EVENT 10046 trace name context forever, level 12
Statement processed.
The level can affect the behaviour of the event.Event 10046 can have level with following
values:
Trace Name Level Description
TRACE_ACALL 1 Trace all calls
TRACE_ECALL 2 Trace “enabled” calls
TRACE_AEXCP 4 Trace all exceptions
TRACE_EEXCP 8 Trace “enabled” exceptions
TRACE_CIRCULAR 16 Trace w/ circular buffer
TRACE_BIND_VARS 32 Trace bind variables
Other combinations :
Level Description
17 Trace all calls, using the buffer
22 Trace enabled calls and all exceptions using the buffer
32 Trace bind variables, without using the buffer
53 Yields the maximum level of tracing, using the buffer
37 Yields the maximum level of tracing, without using the buffer
oradebug session_event
Set trace event in session.
Syntax Parameter
oradebug session_event <text>> <text> Event name
Example
SQL>oradebug session_event 10046 trace name context forever,level 12
Statement proceed.
SQL > oradebug session_event 10046 trace name context off
Statement proceed.
The information goes to user dump destination.
oradebug dumpvar
Print/dump a fixed PGA/SGA/UGA variable.
Syntax Parameter
oradebug dumpvar <p|s|uga> <name> [level] <p|s|uga> PGA,SGA or UGA
<name> Variable name
[level] Level
Example
SQL> oradebug setmypid
Statement processed.
SQL> oradebug dumpvar sga kslwlst
ksllt kslwlst_ [200040AC, 20004174) = 00000000 00000009 00000000 00000000
00000000 00000000 00000000 00000000 00000000 000000
00 00000000 00000000 00000000 …
Let’s change variable value
SQL> oradebug poke 536887468 4 1
BEFORE: [200040AC, 200040B0) = 00000000
AFTER: [200040AC, 200040B0) = 00000001
SQL> oradebug dumpvar sga kslwlst
ksllt kslwlst_ [200040AC, 20004174) = 00000001 00000009 00000000 00000000
00000000 00000000 00000000 00000000 00000000 000000
00 00000000 00000000 00000000 …
oradebug setvar
Modify a fixed PGA/SGA/UGA variable.
Syntax Parameter
oradebug setvar <p|s|uga> <name>
<value>
<p|s|uga> PGA,SGA or UGA
<name> Variable name
<value> Variable’s new value
Example:
SQL> oradebug setmypid
Statement processed.
SQL> oradebug dumpvar sga kcfdfk
kfil kcfdfk_ [2000F6B0, 2000F6B4) = 00000190
SQL> show parameter db_files;
NAME TYPE VALUE
———————————— ———– ——————-
db_files integer 200
SQL> oradebug setvar sga kcfdfk 200
BEFORE: [2000F6B0, 2000F6B4) = 00000190
AFTER: [2000F6B0, 2000F6B4) = 000000C8
SQL> oradebug dumpvar sga kcfdfk
kfil kcfdfk_ [2000F6B0, 2000F6B4) = 000000C8
oradebug peek
This command will dump memory address to a trace file which can be found in user dump
destination.
Syntax Parameters
oradebug peek <addr> <len> [level]
<addr> memory address
<len> length
[level level
Example
select fsv.KSMFSNAM,sga.*
from x$ksmfsv fsv, x$ksmmem sga
where sga.addr=fsv.KSMFSADR
and fsv.ksmfsnam like ‘kgl%’
SQL> /
KSMFSNAM ADDR INDX INST_ID KSMMMVAL
—————————————————————- ——– ———- ———- ——–
kglt1_ 200150F8 21566 1 0000011C
kgllat_ 20015F64 22489 1 00
kglpnl_ 2001602C 22539 1 00
kglpal_ 200160F4 22589 1 00
kglllt_ 200161BC 22639 1 00
SQL> oradebug peek 536957176 4
[200150F8, 200150FC) = 0000011C
oradebug poke
Modify memory.
Syntax Parameters
oradebug poke <addr> <len> [level]
<addr> memory address
<len> length
<value> value
Example
SQL> oradebug help poke
POKE <addr> <len> <value> Modify memory
SQL> oradebug poke 536957176 4 668
BEFORE: [200150F8, 200150FC) = 0000011C
AFTER: [200150F8, 200150FC) = 0000029C
select fsv.KSMFSNAM,sga.*
from x$ksmfsv fsv, x$ksmmem sga
where sga.addr=fsv.KSMFSADR
and fsv.ksmfsnam like ‘kgl%’
SQL> /
KSMFSNAM ADDR INDX INST_ID KSMMMVAL
—————————————————————- ——– ———- ———- ——–
kglt1_ 200150F8 21566 1 0000029C
kgllat_ 20015F64 22489 1 00
kglpnl_ 2001602C 22539 1 00
kglpal_ 200160F4 22589 1 00
kglllt_ 200161BC 22639 1 00
NOTE: The oradebug poke command is a very danger command. Please do not run this command
in production database.
oradebug wakeup
Wake up process .
Syntax Parameter
oradebug wakeup <orapid> <orapid> Oracle PID
Example
You could post smon to cleanup the temporary segments using this command. This will
wakeup smon to clean up the temporary segments
SQL> select pid
from v$process p, v$bgprocess b
where b.paddr = p.addr
and name=’SMON’;
PID
———-
6
SQL> oradebug wakeup 6
oradebug suspend
oradebug also allows you to suspend a process. Firstly you need to identify the shadow process
that you want to suspend. Then set your debug session to point to that process.
Syntax Parameter
oradebug suspend None.
Example
SQL> oradebug setospid 19272
Oracle pid: 26, Unix process pid: 19272, image: oracle@apollo (TNS V1-V3)
and then suspend its execution:
Sqlplus > oradebug suspend
Statement processed.
This stops a process .Examining v$session_wait shows that it is waiting on debugger.
oradebug resume
Resume suspended process.
Syntax Parameter
oradebug resume None.
Example
Resume the process which was already suspended:
SQL> oradebug resume
oradebug flush
Flush pending writes to trace file.
Syntax Parameter
oradebug flush None.
oradebug close_trace
Close trace file.
Syntax Parameter
oradebug close_trace None.
Example
This option is very useful if you have deleted a trace file with the session still live and
now you want the session to resume tracing, but a new file doesn’t appear.The reason
why you have a problem under Unix is that the trace file is not closed – even if you set
sql_trace to false.
select spid, pid
from v$process
where addr = (select paddr from v$session where sid = <your SID >);
oradebug setorapid {the pid above} or oradebug setospid {the spid above} then
oradebug flush
oradebug close_trace
The close_trace option is that you can do it even after you have deleted the trace file
from the operating system level.
oradebug tracefile_name
Get name of the trace file.
Syntax Parameter(s)
oradebug tracefile_name None.
The lkdebug and nsdbx are utilities within the oradebug utility. They are intended for OPS/RAC.
oradebug lkdebug
SQL> oradebug lkdebug help
Usage:lkdebug [options]
-l [r|p] <enqueue pointer> Enqueue Object
-r <resource pointer> Resource Object
-b <gcs shadow pointer> GCS shadow Object
-p <process id> client pid
-P <process pointer> Process Object
-O <i1> <i2> <types> Oracle Format resname
-a <res/lock/proc/pres> all <res/lock/proc/pres> pointers
-a <res> [<type>] all <res> pointers by an optional type
-a convlock all converting enqueue (pointers)
-a convres all res ptr with converting enqueues
-a name list all resource names
-a hashcount list all resource hash bucket counts
-t Traffic controller info
-s summary of all enqueue types
-k GES SGA summary info
oradebug nsdbx
Invoke Cluster Group Services (CGS) name-service debugger. The nsdbx is utility within the
oradebug utility.
SQL> oradebug nsdbx help
Usage:nsdbx [options]
-h Help
-p <owner> <namespace> <key> <value> <nowait> Publish a name-entry
-d <owner> <namespace> <key> <nowait> Delete a name-entry
-q <namespace> <key> Query a namespace
-an <namespace> Print all entries in namespace
-ae Print all entries
-as Print all namespaces
oradebug -G
Parallel oradebug command prefix.
Syntax Parameter
oradebug -G <Inst-List | def | all> <Inst-List | Instance list
def | Default.
all> All instances.
Example
ORADEBUG [-g [DEF | INSTLIST]] subcommand subcommand-parameters
oradebug -g def event 10706 trace name context forever, level 10
oradebug -R
Parallel oradebug prefix.
Syntax Parameter
oradebug -R <Inst-List | def | all> <Inst-List | Instance list
def | Default.
all> All instances.
oradebug setinst
Set instance(s).
Syntax Parameter
oradebug setinst <instance# .. | all> <instance# .. | instance list in double quotes
all> set all instances
Example
SQL> select * from v$active_instances;
INST_NUMBER INST_NAME
———– ———————————
1 alpha:test1
2 beta:test2
3 omega:test3
SQL> oradebug setinst “1”,”2″,”3″
Statement processed. or
SQL> oradebug setinst all
Statement processed.
oradebug sgatofile
Dump SGA to file.
Syntax Parameter
oradebug sgatofile <SGA dump dir>
<SGA dump dir> SGA Directory name in
double quotes.
oradebug dmpcowsga
Dump & map SGA as COW(Copy On Write).
Syntax Parameter(s)
oradebug dmpcowsga <SGA dump dir> <SGA dump dir> SGA Directory name in
double quotes.
oradebug mappcowsga
Dump & map SGA as COW(Copy On Write). Shared(cow) where cow stands for ‘Copy On Write’
is memory that will write through the cache into real memory.
Syntax Parameter(s)
oradebug mappcowsga <SGA dump dir> <SGA dump dir> SGA Directory name in
double quotes.
Example
SQL> oradebug ffbegin
Statement processed.
SQL> oradebug dmpcowsga “/ora-main/app/oracle/admin/test/udump”
Statement processed.
[apollo]/ora-main/app/oracle/admin/test/udump/Aug__1_19:39:31_2003>
SQL> oradebug sgatofile “/ora-main/app/oracle/admin/test/udump”
Statement processed.
SQL> oradebug mapcowsga “/oramain/
app/oracle/admin/test/udump/Aug__1_19:39:31_2003”
Statement processed.
oradebug hanganalyze
Analyze system hang.
Syntax Parameter
oradebug hanganalyze <level> <level>
The levels are defined as follows:
Dump
Level Dump Contains
1-2 Only HANGANALYZE output, no process dump at all
3 Level 2 + Dump only processes thought to be in a hang (IN_HANG state)
4 Level 3 + Dump leaf nodes (blockers) in wait chains (LEAF,LEAF_NW,IGN_DMP
state)
5 Level 4 + Dump all processes involved in wait chains (NLEAF state)
10 Dump all processes (IGN state)
Example
To perform cluster wide HANGANALYZE use the following syntax:
ORADEBUG setmypid
ORADEBUG setinst all
ORADEBUG -g def hanganalyze <level>
oradebug ffbegin
Flash Freeze the Instance.
Syntax Parameter
oradebug ffbegin None
oradebug ffderegister
Flash Freeze deregister instance from cluster
Syntax Parameter
oradebug ffderegister None
oradebug ffterminst
Call exit and terminate instance.
Syntax Parameter
oradebug ffterminst None
oradebug ffresumeinst
Resume the flash frozen instance.
Syntax Parameter
oradebug ffresumeinst None
oradebug ffstatus
Flash freeze status of instance.
Syntax Parameter
oradebug ffstatus None
oradebug skdsttpcs
Helps translate PCs to names.
Syntax Parameter
oradebug skdsttpcs <ifname> <ofname> <ifname> File name
<ofname>
oradebug watch
Watch a region of memory.
Syntax Parameter
oradebug watch<address> <len> <self|exist|all|target> < address>
<len>
<self|exist|all|target>
oradebug delete
Delete a watchpoint.
Syntax Parameter
oradebug delete <local|global|target> watchpoint <id> < local|global|target>
watchpoint <id>
oradebug show
Show watchpoints.
Syntax Parameter
oradebug show <local|global|target> watchpoints < local|global|target> watchpoints
Example
Before you run this command you need to set init parameter _ use_ism=false (intimate
shared memory).Using ISM greatly reduces the overhead in the virtual-to-physical
address translation layers for large Oracle instances, and also provides the feature for
locking shared pages, eliminating any page outs.
SQL> oradebug setmypid
Statement processed.
SQL> oradebug dump errorstack 3
Statement processed.
SQL> oradebug help watch
WATCH <address> <len> <self|exist|all|target> Watch a region of memory
SQL> oradebug watch 4290682200 1 self
Local watchpoint 0 created on region [0xFFBE9D58, 0xFFBE9D59).
SQL> oradebug help show
SHOW <local|global|target> watchpoints Show watchpoints
SQL> oradebug show local watchpoints
ID Address Nbytes Mode
==============================================================
0 0xFFBE9D58 1 SELF
SQL> oradebug help delete
DELETE <local|global|target> watchpoint <id> Delete a watchpoint
SQL> oradebug delete local watchpoint 0
Local watchpoint 0 deleted on region [0xFFBE9D58, 0xFFBE9D59).
SQL> oradebug show local watchpoints
ID Address Nbytes Mode
oradebug core
Dump core without crashing process.
Syntax Parameter
oradebug core None.
oradebug ipc
command list semaphores and shared memory segments in use.Set process id before using it.
Also this option shows which network is Oracle using for RAC traffic.
Syntax Parameter(s)
oradebug ipc None.
Example
List semaphores and shared memory segments in use:
SQL> oradebug setmypid
Statement processed.
SQL> oradebug ipc
Information written to trace file.
——— part of the trace file —————————-
Number of semaphores per set: = 77
Semaphores key overhead per set: = 4
User Semaphores per set: = 73
Number of semaphore sets: = 3
Semaphore identifiers: = 3
Semaphore List=
2293760
————– system semaphore information ————-
IPC status from <running system> as of Tue Jul 22 13:49:16 EDT 2003
T ID KEY MODE OWNER GROUP CREATOR CGROUP NSEMS
OTIME CTIME
Semaphores:
s 2293760 0xddce3cac –ra-r—– oracle dba oracle dba 77 10:32:36 11:06:49
s 524289 0xddce3cad –ra-r—– oracle dba oracle dba 77 no-entry 11:06:49
s 524290 0xddce3cae –ra-r—– oracle dba oracle dba 77 11:06:50 11:06:49
s 983043 0x3f1b2fd4 –ra-r—– oracle dba oracle dba 129 13:44:25 11:03:38
s 196612 0xa5a509ac –ra-r—– oracle dba oracle dba 129 11:51:22 11:04:38
s 1507333 0x9bf960c8 –ra-r—– oracle dba oracle dba 129 10:33:43 10:14:12
Alternative is to use oracle sysresv command which is located at $ORACLE_HOME/bin directory.
Example
Which network is Oracle using for RAC traffic:
SSKGXPT 0x1a2932c flags SSKGXPT_READPENDING info for network 0
socket no 10 IP 172.16.193.1 UDP 43739
sflags SSKGXPT_WRITESSKGXPT_UP info for network 1
socket no 0 IP 0.0.0.0 UDP 0…
So you can see that we are using IP 172.16.193.1 with a UDP protocol.
oradebug unlimit
Remove the file size limit. Useful when need trace file larger then size specified by
max_dump_size parameter.
Syntax Parameter
oradebug unlimit None
Example
oradebug procstat
Dump process Statistics.
Syntax Parameter
oradebug procstat <ospid> <ospid> OS PID
Example
Dump statistics for the DBWR background process:
select pid,name
from v$process p, v$bgprocess b
where b.paddr = p.addr
SQL> /
PID NAME
———- —–
2 PMON
3 DBW0
4 LGWR
5 CKPT
6 SMON
7 RECO
6 rows selected.
SQL> oradebug setorapid 3
Unix process pid: 15668, image: oracle@apollo (DBW0)
SQL> oradebug procstat
Statement processed.
To find out where is the trace file located run:
SQL> oradebug tracefile_name
/ora-main/app/oracle/admin/test/bdump/test_dbw0_15668.trc
SQL>
oradebug call
Invoke function with arguments.
Syntax Parameters
oradebug call <func> [arg1] … [argn] <func> function name
[arg1] … [argn] function’s argument(s)
ORADEBUG DUMPS
Oradebug can be used to obtain information about internal database structures.
oradebug dump
Invoke named dump.
Syntax Parameter
oradebug dump <dump_name> <level> [addr] <dump_name>
<level>
[<addr>]
To see all the available list of dumps, use the “oradebug dumplist” command. It is very useful to
know the dump list, because it is not documented with “alter session set events.” You can also use
the “alter session set events” command to take a dump.
Excerpt from the oradebug dumplist command:
SQL> oradebug dumplist
EVENTS
TRACE_BUFFER_ON
TRACE_BUFFER_OFF
HANGANALYZE
LATCHES
PROCESSSTATE
SYSTEMSTATE
INSTANTIATIONSTATE
REFRESH_OS_STATS
CROSSIC
CONTEXTAREA
HEAPDUMP
HEAPDUMP_ADDR
POKE_ADDRESS
POKE_LENGTH ……….
Dumps of State Objects
oradebug dump systemstate
Dump of all state objects for all the processes on the system
Syntax Parameter
oradebug dump systemstate <level> <level>
Example
SQL> oradebug setmypid
Statement processed.
SQL> oradebug unlimit
Statement processed.
SQL> oradebug setinst all
Statement processed.
SQL> oradebug -g def dump systemstate 10
Statement processed.
oradebug dump processstate
Dump of all state objects for process
Syntax Parameter
oradebug dump processstate <level> <level>
Example
SQL> oradebug setmypid
Statement processed.
SQL> oradebug -g all dump processtate 10
Statement processed.
oradebug dump errorstack
Dump of the process call stack and other information.
Syntax Parameter
oradebug dump errorstack <level> <level>
The levels for the errorstack dump are as follows:
Dump
Level Dump Contains
0 dump error buffer
1 level 0 + call stack
2 level 1 + process state objects
3 level 2 + context area
Example
SQL> oradebug setospid 13446
Oracle pid: 12, Unix process pid: 13446, image: oracle@apollo (TNS V1-V3)
SQL> oradebug unlimit
Statement processed.
SQL> oradebug dump errorstack 3
Statement processed.
File Dumps
oradebug dump controlf
The contents of the current controlfile can be dumped in text form to a process trace file in the
user_dump_dest directory using the CONTROLF dump.
Syntax Parameter
oradebug dump controlf <level> <level>
The levels for this dump are as follows.
Dump
Level Dump Contains
1 only the file header
2 just the file header, the database info record, and checkpoint progress records
3 all record types, but just the earliest and latest records for circular reuse record types
4 as above, but includes the 4 most recent records for circular reuse record types
5+ as above, but the number of circular reuse records included doubles with each level
Example
SQL> oradebug setospid 19272
Oracle pid: 26, Unix process pid: 19272, image: oracle@tomcat (TNS V1-V3)
SQL> oradebug dump controlf 4
Statement processed.
oradebug dump file_hdrs <level>
Dump datafile headers.
Syntax Parameter
oradebug dump file_hdrs <level> <level>
The levels for this dump are as follows.
Dump
Level Dump Contains
1 Record of datafiles in controlfile ( for practice compare with controlfile dump)
2 Level 1 + generic information
3 Level 2 + additional datafile header information.
Increasing level more than 3 do not provide additional information ( size of trace files are identical
for levels equivalent or greater than 3.
-rw-r—– 1 oracle dba 119345 Feb 2 20:58 demo1_ora_3788.trc
-rw-r—– 1 oracle dba 119345 Feb 2 21:03 demo1_ora_8043.trc
-rw-r—– 1 oracle dba 119347 Feb 2 21:07 demo1_ora_10607.trc
Also you can use command alter system dump datafile <file_number> block <block_id>;
to dump one block .
To dump one or more blocks:
alter system dump datafile <file_number> block min <first block > block max <last block >;
Example
select segment_name, header_file, header_block from dba_segments
where segment_type=’ROLLBACK’;
SEGMENT_NAME HEADER_FILE HEADER_BLOCK
————— ———– ————
SYSTEM 1 2
RBS0 2 2
RBS1 2 3202
RBS2 2 6402
oradebug dump redohdr
Dump redo headers.
Syntax Parameter
oradebug dump redohdr <level> <level>
The levels for this dump are as follows.
Dump
Level Dump Contains
1 Record of log file records in controlfile
2 Level 1 + generic information
3 Level 2 + additional log file header information.
Memory Dumps
oradebug dump buffers
Dump of buffer cache.
Syntax Parameter
oradebug dump buffers <level> <level>
The level number to specify in the event syntax is the decimal tablespace relative data block
address.
The levels for the BUFFERS dump are as follows:
Dump
Level Dump Contains
1 dump the buffer headers only
2 include the cache and transaction headers from each block
3 include a full dump of each block
4 dump the working set lists and the buffer headers and the cache header for each block
5 include the transaction header from each block
6 include a full dump of each block
Most levels high than 6 are equivalent to 6, except that levels 8 and 9 are the same as 4 and 5
respectively.
For level 1 to 3 the information is dumped in buffer header order.
For levels higher than 3, the buffers and blocks are dumped in hash chain order.
oradebug dump library_cache
Dump library cache statistics.
Syntax Parameter
oradebug dump library_cache <level> <level>
The levels for the library cache dump are as follows :
Dump
Level Dump Contains
1 dump libracy cache statistics
2 also include a hash table
3 level 2 + dump of the library object handles
4 Level 3 + dump of the heap
Example
SQL> oradebug setmypid
Statement processed.
SQL> oradebug dump library_cache 2
Statement processed.
oradebug dump heapdump
Dump structure of a memory heap.
Syntax Parameter
oradebug dump heapdump <level> <level>
The levels for the heapdump are as follows :
Dump
Level Dump Contains
1 include PGA heap
2 include Shared Pool
4 include UGA heap
8 include CGA heap
16 include Top CGA
32 include Large Pool
oradebug dump heapdump_addr
Syntax Parameter
oradebug dump heapdump_addr<level><address> <level>
<address> descriptor address
The levels for the heapdump_addr are as follows :
Dump
Level Dump Contains
1 dump structure
2 also include contents
Example
SQL> oradebug setmypid
Statement processed.
SQL> oradebug unlimit
Statement processed.
SQL> oradebug dump heapdump 2
Statement processed.
—————— part of the trace file ——————–
*** SESSION ID:(7.14111) 2003-09-03 13:01:21.412
******************************************************
HEAP DUMP heap name=”sga heap” desc=0x80000030
extent sz=0xfc4 alt=48 het=32767 rec=9 flg=2 opc=0
parent=0 owner=0 nex=0 xsz=0x3d2bdf4
EXTENT 0
Chunk b5815ff8 sz= 41699524 perm “perm ” alo=19395672
Chunk b7fda8bc sz= 887380 free ” ”
Chunk b80b3310 sz= 560 freeable “library cache ” ds=b80b5a0c
Chunk b80b3540 sz= 2588 freeable “sql area ” ds=b80b5898
Chunk b80b3f5c sz= 732 freeable “sql area ” ds=b80ba69c
Open the trace file and look for the ds (descriptor address).Convert hex to decimal and do the
dump.
SQL> oradebug dump heapdump_addr 1 3087751692
————————— part of the trace file generated using command above ————-
Statement processed.
*** 2003-09-03 13:12:35.330
*** SESSION ID:(8.20679) 2003-09-03 13:12:35.322
HEAP DUMP heap name=”library cache” desc=0xb80b5a0c
extent sz=0x224 alt=32767 het=8 rec=9 flg=2 opc=0
parent=80000030 owner=b80b5804 nex=0 xsz=0x224
EXTENT 0
Chunk b80b3324 sz= 464 perm “perm ” alo=176
Chunk b80b34f4 sz= 76 freeable “kgltbtab ”
EXTENT 1
Chunk b80b55b4 sz= 500 perm “perm ” alo=500
Chunk b80b57a8 sz= 40 free ” ”
EXTENT 2
Chunk b80b57f4 sz= 244 perm “perm ” alo=244
Chunk b80b58e8 sz= 52 free ” ”
Chunk b80b591c sz= 76 freeable “kgltbtab ”
Chunk b80b5968 sz= 76 freeable “kgltbtab ”
INDEX DUMP
oradebug dump treedump
Dumps the structure of an index tree. The dump file contains one line for each block in the tree,
indented to show its level, together with a count of the number of index entries in the block.
Syntax Parameter
oradebug dump treedump <object_id> <level> object_id
Example
select object_id from sys.dba_objects
where owner = upper(‘&Owner’) and
object_name = upper(‘&IndexName’);
SQL> oradebug setmypid
Statement processed.
SQL> oradebug dump treedump 40
Statement processed.
Instead of oradebug dump treedump command you can also use
alter session set events ‘immediate trace name treedump level n’;
That will give you a trace file with the one line for each block in the B*-tree and a row
count for each block.If there are large numbers of empty or nearly empty blocks, then the
index is a good candidate for being rebuilt.
Conclusion
To conclude, oradebug utility gives the dba another piece of important information that helps in
identifying and resolving different kind of database issues.
No liability for the contents of this documents can be accepted. Use the concepts, examples and
other content at your own risk. As this is a first version, there may be errors and inaccuracies, that
may of course be damaging to your system. Proceed with caution, and although this is highly
unlikely, the author does not take any responsibility for that.
References
Metalink – Oracle Corporation
Doc ID: 39817.1 Interpreting Raw SQL_TRACE and dbms_support.start_trace output
Doc ID: 28863.1 ORADBX – Quick Reference.
Doc ID: 175006.1 Steps to generate hanganalyze trace files.
Doc ID: 105395.1 How to find PID for setospid in oradebug.
Doc ID: 205809.1 Script to Collect OPS Diagnostic Information.
Doc ID: 123322.1 SYSRESV Utility.
Doc ID: 68281.1 Determinig which instance owns which shared memory & semaphore
segments.
Doc ID: 215858.1 Interpreting hanganalyze trace files to diagnose hanging and performance
problems.
Doc ID: 2112587.6 How to take OPS-aware Oradebug dump in 8i multiple instances database.
Books
Oracle8i Internal Services for Waits, Latches, Locks and Memory – Steve Adams
Solaris Internals – published by Jim Mauro and Richard McDougall.
White Papers
Oracle X$ Tables – Steve Adams
09’97 SunWorld article Shared memory uncovered by Jim Mauro
Oracle9i Memory Management: Easier Than Ever , Sushil Kumar, Oracle Corporation
Class
Oracle Internals and Advanced Performance Tuning- Master Class Copenhagen, Denmark 2003
Web Resources :
http://www.ixora.com.au/ site authored by Steve Adams.
http://www.jlcomp.demon.co.uk/ site authored by Jonathan Lewis
http://freespace.virgin.net/bill.doyle/ork_trc.htm
http://www.oracleadvice.com/Tips/9ibreak.htm
.