all about tracing oracle sql sessions

8/8/2019 All About Tracing Oracle SQL Sessions

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HOW TO trace your own session

Platform: Oracle App:DB Ver: 9.2 App Ver:Revision

Date:

28-Nov-2005 Keywords: HOWTO, TRACE, SESSION

GoalTo trace the SQL in your own sessionFactsSolution

First, run the following commands from the SQL*Plus command prompt to switchon timed statistics and to allow for an unlimited trace file size.

alter session set timed_statistics=true

alter session set max_dump_file_size=unlimited

If you fail to set TIMED_STATISTICS=TRUE, your database kernel will emit onlyzero values instead of real durations into your trace file. If your setting ofMAX_DUMP_FILE_SIZE is too restrictive, you'll suffer the chagrin of generating amessage like the following in your trace file instead of the timing data youwanted:

*** DUMP FILE SIZE IS LIMITED TO 1048576 BYTES ***

Before starting your trace, you can modify the name of the trace file by adding aTRACEFILE_IDENTIFIER to it. You can do this by an ALTER SESSION commandsuch as what is below.

alter session set TRACEFILE_IDENTIFIER = 'something_unique';

Next comes activating the trace itself. There are several ways to do this. The old-fashioned way is to use the ALTER SESSION command as follows:

alter session set events '10046 trace name context forever, level

12'

/* code to be traced goes here */

alter session set events '10046 trace name context off'

A more elegant way to accomplish the extended SQL trace activation is to usethe DBMS_SUPPORT package:

dbms_support.start_trace(waits=>true, binds=>true)/* code to be traced goes here */

dbms_support.stop_trace()

To find the trace file, first find the directory where it is located using thefollowing:

select value from v$parameter where name = 'user_dump_dest';


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Then, look for a file with 'something_unique' in the filename.

HOW TO trace a 3rd party session

Platform: Oracle App:DB Ver: 9.2 App Ver:RevisionDate:

26-Oct-2006 Keywords:HOWTO, TRACE, SESSION, 3RD PARTY

GoalTo trace the SQL in 3rd party sessionFactsSolutionFirst, identify the 3rd party session to be traced. This can be cumbersome, but can be identsession has been identified make a note of the session's:

SID

Serial#

Next, run the following commands from the SQL*Plus command prompt to switch on timedstatistics and to allow for an unlimited trace file size.

alter session set timed_statistics=true

alter session set max_dump_file_size=unlimited

If you fail to set TIMED_STATISTICS=TRUE, your database kernel will emit only zero valuesinstead of real durations into your trace file. If your setting of MAX_DUMP_FILE_SIZE is toorestrictive, you'll suffer the chagrin of generating a message like the following in your trace file

instead of the timing data you wanted:

*** DUMP FILE SIZE IS LIMITED TO 1048576 BYTES ***

Before starting your trace, you can modify the name of the trace file by adding aTRACEFILE_IDENTIFIER to it. You can do this by an ALTER SESSION command such as whatis below.

alter session set TRACEFILE_IDENTIFIER = 'something_unique';

Next comes activating the trace itself. There are several ways to do this. The old-fashioned way isto use the ALTER SESSION command as follows:A more elegant way to accomplish the extended SQL trace activation is to use theDBMS_SYSTEM package:

DBMS_System.Set_Ev(sid, serial#, event, level, name);

e.g.

DBMS_System.Set_Ev(31, 97, 10046, 4,);

To find the trace file, first find the directory where it is located using the following:


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select value from v$parameter where name = 'user_dump_dest';

Then, look for a file with 'something_unique' in the filename.


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Structure of an Extended SQL Trace file

Platform: Oracle App:DB Ver: 9.2 App Ver:Revision

Date:

30-Dec-

2005

Keywords: REF, REFERENCE, TRACE FILE STRUCTURE

ReferenceFor any updates, refer to the original Metalink document Metalink:39817.1.

Introduction.between any 2 operations

This is a short reference article which summarises the output format of the rawSQL_TRACE output file. The second part of the article describes the additionaltrace lines that may be enabled by the DBMS_SUPPORT package. See MetalinkNote 62294.1 for details of this package.Note: The format may vary slightly between releases.

APPNAME mod='%s' mh=%lu act='%s' ah=%luAPPNAME Application name setting. (This only applies to Oracle 7.2

and above. This can be set by using the

DBMS_APPLICATION_INFO package. See Note 30366.1.)

mod Module name.

mh Module hash value.

act Action.

ah Action hash value.

PARSING IN CURSOR # len=X dep=X uid=X oct=X lid=X tim=X hv=Xad='X' END OF STMT Cursor number.

len Length of SQL statement.

dep Recursive depth of the cursor.uid Schema user id of parsing user.

oct Oracle command type.

lid Privilege user id.

tim Timestamp.

Pre-Oracle9i, the times recorded by Oracle only have a

resolution of 1/100th of a second (10mS). As of Oracle9i

some times are available to microsecond accuracy

(1/1,000,000th of a second).

The timestamp can be used to determine times between points

the trace file. The value is the value in V$TIMER when the

line was written. If there are TIMESTAMPS in the file you

can use the difference between 'tim' values to determine an

absolute time.hv Hash id.

ad SQLTEXT address (see and ).

The actual SQL statement being parsed.

PARSE ERROR #%d:len=%ld dep=%d uid=%ld oct=%d lid=%ld tim=%lu err=%d ...
http://metalink.oracle.com/metalink/plsql/ml2_documents.showDocument?p_database_id=NOT&p_id=39817.1http://metalink.oracle.com/metalink/plsql/ml2_documents.showDocument?p_database_id=NOT&p_id=39817.1


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PARSE ERROR In Oracle 7.2+ parse errors are reported to the trace

file.

len Length of SQL statement.

dep Recursive depth of the statement

uid User id.

oct Oracle command type (if known).

lid Privilege user id.

tim Timestamp.

err Oracle error code (e.g. ORA-XXXXX) reported

The SQL statement that errored.

If this contains a password, the statement is truncated as

indicated by '...' at the end.

PARSE #:c=0,e=0,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=4,tim=0EXEC #:c=0,e=0,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=4,tim=0FETCH #:c=0,e=0,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=4,tim=0UNMAP #:c=0,e=0,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=4,tim=0

- OPERATIONS:

PARSE Parse a statement.

EXEC Execute a pre-parsed statement.

FETCH Fetch rows from a cursor.

UNMAP If the cursor uses a temporary table, when the cursor is

closed you see an UNMAP when we free up the temporary table

locks.(Ie: free the lock, delete the state object, free the

temp segment)

In tkprof, UNMAP stats get added to the EXECUTE statistics.

SORT UNMAP

As above, but for OS file sorts or TEMP table segments.

c CPU time (100th's of a second in Oracle7 ,8 and 9).

e Elapsed time (100th's of a second Oracle7, 8 and 1,000,000ths(Microseconds) in Oracle 9 onwards).

p Number of physical reads.

cr Number of buffers retrieved for CR reads.

cu Number of buffers retrieved in current mode.

mis Cursor missed in the cache.

r Number of rows processed.

dep Recursive call depth (0 = user SQL, >0 = recursive).

og Optimizer goal: 1=All_Rows, 2=First_Rows, 3=Rule, 4=Choose

tim Timestamp (large number in 100ths of a second). Use this to

determine the time

ERROR #%d:err=%d tim=%luSQL Error shown after an execution or fetch error.

err Oracle error code (e.g. ORA-XXXXX) at the top of the stack.tim Timestamp.

STAT # id=N cnt=0 [pid=0 pos=0 obj=0 op='SORT AGGREGATE ']STAT Lines report explain plan statistics for the numbered .

Cursor which the statistics apply to.

id Line of the explain plan which the row count applies to (starts at

line 1). This is effectively the row source row


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count for all row sources in the execution tree.

cnt Number of rows for this row source.

As of 7.3.3 the items in '[...]' are also reported:

pid Parent id of this row source.

pos Position in explain plan.

obj Object id of row source (if this is a base object).op='...' The row source access operation.

These let you know the 'run time' explain plan.

XCTEND rlbk=%d rd_only=%d

XCTEND A transaction end marker.

rlbk 1 if a rollback was performed, 0 if no rollback (commit).

rd_only 1 if transaction was read only, 0 if changes occurred.

==========================================================The items below are only output if WAITS or BINDS are being traced.These can be enabled with the DBMS_SUPPORT package.==========================================================BINDS #%d: bind 0: dty=2 mxl=22(22) mal=00 scl=00 pre=00 oacflg=03 oacfl2=0 size=24offset=0 bfp=02fedb44 bln=22 avl=00 flg=05 value=10

BIND

Variables bound

to a cursor.

bindN The bind position being bound.

dty Data type (see ).

mxl Maximum length of the bind variable (private max len

in paren).

mal Array length.

scl Scale.

pre Precision.

oacflg Special flag indicating bind options

oacflg2 Continuation of oacflg

size Amount of memory to be allocated for this chunk

offset Offset into this chunk for this bind buffer

bfp Bind address.

bln Bind buffer length.

avl Actual value length (array length too).

flg Special flag indicating bind status

value The actual value of the bind variable.

Numbers show the numeric value, strings show the

string etc...

WAIT #: nam="" ela=0 p1=0 p2=0 p3=0


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WAIT An event that we waited for.

nam What was being waited for .

The wait events here are the same as are seen in

. For any Oracle release a full list

of

wait events and the values in P1, P2 and P3 below can beseen in

ela Elapsed time for the operation

p1 p1 for the given wait event



Example (Full Table Scan):

WAIT #1: nam="db file scattered read" ela= 5 p1=4 p2=1435 p3=25

WAITing under CURSOR no 1

for "db file scattered read"

We waited 0.05 seconds

For a read of: File 4, start block 1435, for 25 Oracle

blocks

Example (Index Scan):

WAIT #1: nam="db file sequential read" ela= 4 p1=4 p2=1224 p3=1

WAITing under CURSOR no 1

for "db file sequential read"

We waited 0.04 seconds for a single block read (p3=1)

from file 4, block 1224.


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HOW TO find SQL trace file directories

Platform: Oracle App:DB Ver: 9.2 App Ver:Revision Date: 17-Sep-2005 Keyword

s:

HOWTO, TRACE FILES, DIRECTORIES, DIRECTORY

GoalTo find directories on the database server where SQL trace files are locatedFactsSolution

Run the SQL script:

SELECT name, value

FROM v$parameter2

WHERE name IN ('user_dump_dest'

,'background_dump_dest'

,'core_dump_dest')


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HOW TO find a user's session info for tracing

Platform: Oracle App:

DB Ver: 9.2 App Ver:

RevisionDate:

12-Sep-2005 Keywords: HOWTO, TRACING, TRACE, SESSION

GoalTo find a user's session info (ready for tracing)FactsSolution

The following SQL script will find the SID and SERIAL# required to activate asession specific SQL trace, together with supporting information about thatsession.

SELECT

s.sid db_sid

,s.serial# db_serial

,p.spid os_pid

,to_char(s.logon_time, 'YYYY/MM/DD HH24:MI:SS') db_logon_time

,nvl(s.username, 'SYS') db_user

,s.osuser os_user

,s.machine os_machine

,nvl(decode(instr(s.terminal, chr(0))

,0

,s.terminal

,substr(s.terminal, 1, instr(s.terminal, chr(0))-1)),'none')

os_terminal

,s.program os_program

from

v$session s

,v$process p

where 1=1

and s.paddr = p.addr

and s.username like upper('&1')

/


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HOW TO find a concurrent program's trace file

Platform: Oracle App:DB Ver: 9.2 App Ver:Revision Date: 28-Jun-2006 Keyword

s:

HOWTO, TRACE, CONCURRENT PROGRAM

GoalTo find the SQL trace file for a concurrent programFactsSolutionRun the following script:

prompt

ACCEPT request prompt 'Please enter the concurrent request id for

the appropriate concurrent program:'

prompt

COLUMN traceid format a8

COLUMN tracename format a80

COLUMN user_concurrent_program_name format a40

COLUMN execname format a15

COLUMN enable_trace format a12

SET lines 80

SET pages 22

SET head OFF

SELECT

req.request_id

,req.logfile_node_name node

,req.oracle_Process_id

,req.enable_trace

,dest.VALUE||'/'||LOWER(dbnm.VALUE)||'_ora_'||

oracle_process_id||'.trc' trace_filename

,prog.user_concurrent_program_name

,execname.execution_file_name,execname.subroutine_name

,phase_code

,status_code

,ses.SID

,ses.serial#

,ses.module


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,ses.machine

FROM

fnd_concurrent_requests req

,v$session ses

,v$process proc,v$parameter dest

,v$parameter dbnm

,fnd_concurrent_programs_vl prog

,fnd_executables execname

WHERE 1=1

AND req.request_id = &request

AND req.oracle_process_id=proc.spid(+)

AND proc.addr = ses.paddr(+)

AND dest.NAME='user_dump_dest'AND dbnm.NAME='db_name'

AND req.concurrent_program_id = prog.concurrent_program_id

AND req.program_application_id = prog.application_id

AND prog.application_id = execname.application_id

AND prog.executable_id=execname.executable_id


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HOW TO trace SQL*Plus client

Platform: Oracle App:DB Ver: 9.2 App Ver:

RevisionDate: 19-Oct-2005 Keywords: HOWTO, TRACE, SQL*PLUS

GoalSwitch tracing on for the SQL*Plus client applicationFactsSolution

To set up the trace on client:Include the following parameters in SQLNET.ORA file located in$ORACLE_HOME/network/admin:

trace_level_client = 16

trace_file_client = cli.trc

trace_directory_client = c:\tmp

trace_unique_client = on

trace_timestamp_client = on

trace_filelen_client = 100

trace_fileno_client = 2

log_file_client = cli

log_directory_client = c:\tmp

tnsping.trace_directory = c:\tmp

tnsping.trace_level = admin

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