KoopmannZeroingInOnPerformanceInOracle10g

www.pinehorse.com www.dbcorral.com

Zeroing in on Performance in Oracle 10g

James F. KoopmannFounder & President

[email protected]


� N-years of IT/core RDBMS experience� Oracle (V6-10g) 8i & 9i OCP� Contributing Author

Where to Find Me on the NET� Speaker

James F. Koopmann

2 / Month

Daily

technical articles a month

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Database general interest issues

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Database centric vendor reviews

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================

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3-5 / Week

Bimonthly

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As Needed

1 / Month


The Database System

System Statistics

Session Statistics

Merging System & Session Statistics

Session Tracing

TKPROF

Content

zz


User / Job

Request

(workload) User

Decides

What to

Do Next

Database

Completes

Request

Database Response Time

Coffee/Tea Break

Resource Usage

(v$sysstat)

Sorts, Reads, Writes, Enqueues, Redo activity, Buffer cache activity, Parsing,…

User

Queues

Next

Transaction

Think

Time

log file sync,

db file sequential read,…

Wait Times

(v$system_event)

Throughput

The Database System

It’s All About Throughput

Can we relate the workload in our systems against the statistics that inhibit its’ throughputSYSTEM .vs. SESSION Statistics

(V$SESSION, V$SESSION_EVENT, V$SESSION_WAIT, V$SESSTAT,V$SESS_IO)


Why: Disk is slow, memory is fast

The more information in memory, the better performance we

will experience

What: Use to size the buffer caches

Size Internal structures to increase performance

When: Performance .vs. Curiosity

Where: V$BUFFER_POOL_STATISTICS V$DB_CACHE_ADVICE (2K, 4K, 8K, 16K, 32K, KEEP, RECYCLE)

Buffer Cache

SYSTEM Statistics

What should I expect if I change my buffer cache sizes?


SQL> SELECT name, block_size, size_for_estimate,

estd_physical_read_factor, estd_physical_reads

FROM V$DB_CACHE_ADVICE

WHERE advice_status = 'ON';

Buffer Cache - Advisory

How to get the statistics1. Set the db_cache_advice to ‘READY’

2. Set the db_cache_advice to ‘ON’

3. Run a valid workload through the system

4. Oracle populates V$DB_CACHE_ADVICE with samples / usage patterns

5. Just issue the SQL to see report

SYSTEM Statistics


BLOCK Cache Estd Phys Estd PhysNAME SIZE Size Read Factor Reads-------- ----- ----- ----------- ----------DEFAULT 8192 48 2.1133 343669940DEFAULT 8192 96 1.7266 280783364DEFAULT 8192 144 1.4763 240091867DEFAULT 8192 192 1.3573 220733606DEFAULT 8192 240 1.2801 208181172DEFAULT 8192 288 1.2165 197842182DEFAULT 8192 336 1.1686 190052917DEFAULT 8192 384 1.1202 182180544DEFAULT 8192 432 1.0877 176884743DEFAULT 8192 480 1.0602 172420984DEFAULT 8192 528 1.0196 165812231DEFAULT 8192 544 1 162626093DEFAULT 8192 576 .9765 158797352DEFAULT 8192 624 .9392 152735392DEFAULT 8192 672 .9216 149879874DEFAULT 8192 720 .9013 146571255DEFAULT 8192 768 .885 143928671DEFAULT 8192 816 .8726 141908868DEFAULT 8192 864 .8607 139972381

DEFAULT 8192 544 1.00 162626093 CURRENT

Its all about reads

1. Don’t reduce the size of

your cache if you are

going to incur more

physical reads

2. Don’t increase the size of

your cache if you are not

going to reduce the

number of reads

Buffer Cache - Advisory Report

SYSTEM Statistics

What is the cost savings for less physical reads


Why: Know thy transaction better by understanding segment access and

reduce ‘hot tables / objects”

Detection of what tables or indexes are being accessed the most will

allow you to fine tune memory structures and access methodologies.

What: Use to tune memory structures and access methodologies

When: General Investigation

Where: V$SEGSTAT & V$SEGMENT_STATISTICS

Segment Level Statistics

SYSTEM Statistics

What is my code doing


SQL> > SELECT owner,object_type,object_name,value

FROM V$SEGMENT_STATISTICS

WHERE (statistic_name like '%read%‘

OR statistic_name like '%write%')

ORDER BY value desc

How to get the statistics

1. Set STATISTICS_LEVEL to TYPICAL or ALL

2. Run a valid workload through system

3. Issue above SQL

V$SEGMENT_STATISTICS : reads / writes

SYSTEM Statistics


OWNER OBJECT_TYPE OBJECT_NAME VALUE

------- ------------- ------------------- --------

OCPOLTP TABLE OLTP_MANAGER 15752896

OCPOLTP INDEX PK_OLTP_MANAGER 10716704

OCPOLTP INDEX PK_OLTP_SALES 10615296

OCPOLTP TABLE OLTP_SALES_VALUE 8491008

OCPOLTP TABLE OLTP_SALES 7050448

…

Result

What objects are causing the performance bottleneck in relation to reads and writes.

V$SEGMENT_STATISTICS : reads / writes

SYSTEM Statistics

Who, What, ?When?, and ?Impact?


Used with SQL_ADDRESS to identify the SQL statement that is currently being

executed. This SQL_HASH_VALUE is unique, or should be unique, to the same SQL

statement no matter when it is executed. Thus ‘select * from dual’ will always produce the same SQL_HASH_VALUE.

SQL_HASH_VALUE

Used with SQL_HASH_VALUE to identify the SQL statement that is currently being

executed.

SQL_ADDRESS

The type of session connected to the databaseTYPE

This is the operating system process id for the connection. Only given here as a

reference so that you can go look on the O/S side.

PROCESS

Tells us the status of the session. We will be concerned with ACTIVE sessions, those

that are executing SQL

STATUS

The Oracle user (same as from dba_users)USERNAME

Identifies a unique Oracle sessionSID

Identifies a unique Oracle session addressSADDR

DescriptionColumn

V$SESSION

Jump’n off point, OK, Who’s out there

SESSION Statistics


SELECT sid,

to_char(logon_time,'MMDDYYYY:HH24:MI') logon_time,

username,

type,

status,

process,

sql_address,

sql_hash_value

FROM v$session

WHERE username is not null

Inactive session with no SQL executing

SID LOGON_TIME USERNAME TYPE STATUS PROCESS SQL_ADDR SQL_HASH_VALUE

---- -------------- --------- ---- -------- ------------ -------- --------------

140 06252004:06:23 JKOOPMANN USER INACTIVE 3528:3036 00 0

Active session with SQL executing

SID LOGON_TIME USERNAME TYPE STATUS PROCESS SQL_ADDR SQL_HASH_VALUE

---- -------------- --------- ---- -------- ------------ -------- --------------

140 06252004:06:23 JKOOPMANN USER ACTIVE 3528:3036 6879D780 2803425422

Sessions Activity

SESSION Statistics

We have lift-off


SQL_HASH Wait Time

SID User VALUE Wait Event Wait State (ms) P1 P2 P3

--- ----- -------------- ------------------------ ---------- ------ -------------- ------ ---

146 SCOTT 1610159152 SQL*Net message from client WAITING 0 1413697536 1 0

153 JOHN 1610159152 db file scattered read WAITING 0 1 54377 16

241 ALFY 1610159152 db file scattered read WAITING 0 1 54377 16

132 BETTY 1610159152 ksfd: async disk IO WAITED SHO -1 4294967295 32 432

V$SESSION_WAIT

SESSION Statistics

SELECT a.sid,

c.username,

SQL_HASH_VALUE,

b.event,

b.state,

b.wait_time,

b.p1,

b.p2,

b.p

FROM V$SESSION a, V$SESSION_WAIT b, DBA_USERS c, V$PROCESS d

WHERE a.sid = b.sid

AND a.user# = c.user_id

AND a.paddr = d.addr

Where did it go


First poll for i/o

SID BLOCK_GETS CONSISTENT_GETS PHYSICAL_READS BLOCK_CHANGES CONSISTENT_CHANGES

--- ---------- --------------- -------------- ------------- ------------------

150 4 470149 446 4 0

Second poll for i/o

SID BLOCK_GETS CONSISTENT_GETS PHYSICAL_READS BLOCK_CHANGES CONSISTENT_CHANGES

--- ---------- --------------- -------------- ------------- ------------------

150 4 1002523 448 4 0

V$SESS_IO

SESSION Statistics

SELECT sess_io.sid,

sess_io.block_gets,

sess_io.consistent_gets,

sess_io.physical_reads,

sess_io.block_changes,

sess_io.consistent_change

FROM V$SESS_IO sess_io,

V$SESSION session

WHERE sesion.sid = sess_io.sid

AND sesion.username is not null

Yup, Active sessions are do’n I/O. Anyone STUCK in the mud?


V$SQLAREA

10g

10g

The accumulated microseconds elapsed time used by the SQLELAPSED_TIME

The accumulated microseconds of CPU time used by the SQLCPU_TIME

This is the hash value to the parent statement in the library cacheHASH_VALUE

This is the address to the parent of this cursor/sqlADDRESS

The optimizer mode being utilized by the queryOPTIMIZER_MODE

This is the first 1000 characters of the SQL being executed by the user. If more than 1000 characters you should use V$SQL_TEXT which is described latter in the article.

SQL_TEXT

DescriptionColumn

Where are Reads, Writes, and Gets

SESSION Statistics


SELECT sesion.sid,

sesion.username,

optimizer_mode,

hash_value,

address,

cpu_time,

elapsed_time,

sql_text

FROM v$sqlarea sqlarea, v$session sesion

WHERE sesion.sql_hash_value = sqlarea.hash_value

AND sesion.sql_address = sqlarea.address


Active session and the SQL it is executing

SID USERNAME OPTIMIZER_MODE HASH_VALUE ADDRESS CPU_TIME ELAPSED_TIME

---- --------- --------------- ---------- -------- ---------- ------------

150 JKOOPMANN ALL_ROWS 2803425422 6879D780 11923758 12106196

SQL_TEXT

--------------------------------------------------

select a.table_name from dba_tables a,dba_tables b

Extracting the active SQL a user is executing

SESSION Statistics

Look (quick) what I’m doing Ma


SELECT sesion.sid,

sesion.serial#,

sesion.username,

sesion.sql_id,

sesion.sql_child_number,

optimizer_mode,

hash_value,

address,

sql_text






SID SERIAL# USERNAME SQL_ID SQL_CHILD_NUMBER OPTIMIZER_MODE HASH_VALUE ADDRESS

--- ------- --------- ------------- ---------------- -------------- ---------- --------

149 8 JKOOPMANN 5qk509xugpmpv 1 FIRST_ROWS 1962593979 69A7558C

SQL_TEXT

--------------------------------------------------

SELECT count(*) FROM sys.dba_tables WHERE owner = :1


Same old join to get SQL with a #$(& bind variable

SESSION Statistics


V$SQL_BIND_CAPTURE

This is the hash value to the parent statement in the library cache

HASH_VALUE

10g

Value of the bind variableVALUE_STRING

The name of the bind variable.NAME


DescriptionColumn

STATISTICS_LEVEL=ALL

SESSION Statistics


SELECT sesion.sid,

sesion.username,

sesion.sql_id,


sql_bind_capture.name,

sql_bind_capture.value_string

FROM v$sql_bind_capture sql_bind_capture, v$session sesion

WHERE sesion.sql_hash_value = sql_bind_capture.hash_value

AND sesion.sql_address = sql_bind_capture.address



SID USERNAME SQL_ID SQL_CHILD_NUMBER NAME VALUE_STRING

---- ------------ ------------- ---------------- ---- ------------

149 JKOOPMANN 5qk509xugpmpv 1 :1 ORDEROWNER

Extracting bind variable contents for SQL that is executing

Look ma, no traces

SESSION Statistics


SELECT sesion.sid,

sesion.serial#,

sesion.username,

sesion.sql_id,


optimizer_mode,

hash_value,

address,

sql_text






SID SERIAL# USERNAME SQL_ID SQL_CHILD_NUMBER OPTIMIZER_MODE HASH_VALUE ADDRESS

--- ------- --------- ------------- ---------------- -------------- ---------- --------

149 8 JKOOPMANN 5qk509xugpmpv 1 FIRST_ROWS 1962593979 69A7558C

SQL_TEXT

--------------------------------------------------



Same old join to get SQL with a #$(& bind variable

SESSION Statistics


Additional V$SESSION column information

10g

10g

A child number of a SQL statement that is currently being executed

SQL_CHILD_NUMBER

An identifier to the SQL currently executing. SQL_ID

Along with SID uniquely identifies a session and the objects it uses.

SERIAL#

DescriptionColumn

New columns, Hold on!

SESSION Statistics


9i

SELECT * FROM table(DBMS_XPLAN.DISPLAY_CURSOR((’<SQL_ID>'),<SQL_CHILD_NUMBER>));

SELECT * FROM table(DBMS_XPLAN.DISPLAY_CURSOR(('5qk509xugpmpv'),1));

Extract the EXACT Execution Plan

Tired of extracting raw SQL_TEXT, formatting, and producing explain plans

SESSION Statistics


PLAN_TABLE_OUTPUT

----------------------------------------------------------------------------------------------------

SQL_ID 5qk509xugpmpv, child number 1

-------------------------------------


Plan hash value: 580517646

----------------------------------------------------------------------------------------------------

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)|Time|

----------------------------------------------------------------------------------------------------

| 0 | SELECT STATEMENT | | | | 242 (100)| |

| 1 | SORT AGGREGATE | | 1 | 149 | | |

| 2 | NESTED LOOPS | | 1 | 149 | 242 (1)| 03 |

| 3 | MERGE JOIN CARTESIAN | | 1 | 136 | 218 (1)| 03 |

| 4 | NESTED LOOPS OUTER | | 1 | 81 | 194 (1)| 03 |




| 8 | NESTED LOOPS | | 1 | 54 | 191 (1)| 03 |

|* 9 | HASH JOIN | | 8 | 368 | 183 (1)| 03 |

| 10 | NESTED LOOPS | | 7 | 119 | 4 (0)| 01 |

| 11 | TABLE ACCESS BY INDEX ROWID| USER$ | 1 | 14 | 1 (0)| 01 |

|* 12 | INDEX UNIQUE SCAN | I_USER1 | 1 | | 0 (0)| |

| 13 | TABLE ACCESS FULL | TS$ | 7 | 21 | 3 (0)| 01 |

|* 14 | TABLE ACCESS FULL | TAB$ | 16 | 464 | 178 (0)| 03 |

|* 15 | TABLE ACCESS BY INDEX ROWID | OBJ$ | 1 | 8 | 1 (0)| 01 |

|* 16 | INDEX UNIQUE SCAN | I_OBJ1 | 1 | | 0 (0)| |

|* 17 | INDEX UNIQUE SCAN | I_OBJ1 | 1 | 5 | 0 (0)| |

| 18 | TABLE ACCESS CLUSTER | SEG$ | 1 | 11 | 1 (0)| 01 |

|* 19 | INDEX UNIQUE SCAN | I_FILE#_BLOCK# | 1 | | 0 (0)| |

| 20 | TABLE ACCESS BY INDEX ROWID | OBJ$ | 1 | 8 | 1 (0)| 01 |

|* 21 | INDEX UNIQUE SCAN | I_OBJ1 | 1 | | 0 (0)| |

| 22 | TABLE ACCESS CLUSTER | USER$ | 1 | 3 | 1 (0)| 01 |

|* 23 | INDEX UNIQUE SCAN | I_USER# | 1 | | 0 (0)| |

| 24 | BUFFER SORT | | 1 | 55 | 217 (1)| 03 |

|* 25 | FIXED TABLE FULL | X$KSPPI | 1 | 55 | 24 (0)| 01 |

|* 26 | FIXED TABLE FIXED INDEX | X$KSPPCV (ind:2) | 1 | 13 | 24 (0)| 01 |

----------------------------------------------------------------------------------------------------

Extract the EXACT Execution Plan

WOW !!

SESSION Statistics


V$SQL_PLAN_STATISTICS

10g

9i

Number of physical disk reads for the last run of the plan for a given step

LAST_DISK_READS

Number of consistent gets for the last run of the plan for a given step.

LAST_CR_BUFFER_GETS

The number of rows returned OUTPUT_ROWS

The number for each step in the execution planOPERATION_ID

Plan hash valuePLAN_HASH_VALUE

This is the hash value to the parent statement in the library cache

HASH_VALUE


DescriptionColumn

No more global accumulated statistics from V$SQLAREA

SESSION Statistics


SELECT sesion.sid,

sesion.username,

sql_plan_statistics.operation_id “Plan Id",

sql_plan_statistics.last_output_rows "Rows",

sql_plan_statistics.last_cr_buffer_gets "Consistent Gets",

sql_plan_statistics.last_disk_reads "Disk Reads"

FROM v$sql_plan_statistics sql_plan_statistics,

v$session sesion

WHERE sesion.sql_hash_value = sql_plan_statistics.hash_value

AND sesion.sql_address = sql_plan_statistics.address


Extracting plan statistics for execution of a SQL statement

True statistical values accumulated for a SQL statement and each step of the Execution Plan

SESSION Statistics


SID USERNAME Plan Id Rows Consistent Gets Disk Reads

--- -------------- ---------- ---------- --------------- ----------

149 JKOOPMANN 1 1 8594 0

149 JKOOPMANN 2 643 8594 0

149 JKOOPMANN 3 643 8594 0

149 JKOOPMANN 4 643 8594 0

149 JKOOPMANN 5 643 7540 0

149 JKOOPMANN 6 643 6369 0

149 JKOOPMANN 7 643 4614 0

149 JKOOPMANN 8 643 3969 0

149 JKOOPMANN 9 1572 823 0

149 JKOOPMANN 10 7 11 0

149 JKOOPMANN 11 1 2 0



149 JKOOPMANN 14 1572 812 0

149 JKOOPMANN 15 643 3146 0

149 JKOOPMANN 16 1572 1574 0

149 JKOOPMANN 17 50 645 0

149 JKOOPMANN 18 555 1755 0

149 JKOOPMANN 19 555 645 0

149 JKOOPMANN 20 526 1171 0

149 JKOOPMANN 21 526 645 0

149 JKOOPMANN 22 526 1054 0

149 JKOOPMANN 23 526 2 0

149 JKOOPMANN 24 643 0 0


149 JKOOPMANN 26 643 0 0

Extracting plan statistics for execution of a SQL statement

SESSION Statistics


$SQL_OPTIMIZER_ENV10g

Parameter valueVALUE

Show if the parameter is set to it’s default value.ISDEFAULT

Parameter nameNAME

This is the hash value to the parent statement in the library cacheHASH_VALUE


DescriptionColumn

Does your environment change depending on application or user sessionHow many times have you chased an issue only to find out the user changed environmentsHave any third party products. Do they do this.

SESSION Statistics


SELECT sesion.sid,

sesion.username,

name,

isdefault,

value

FROM v$sql_optimizer_env sql_optimizer_env, v$session sesion

WHERE sesion.sql_hash_value = sql_optimizer_env.hash_value

AND sesion.sql_address = sql_optimizer_env.address


Optimizer environment settings for current active SQL

SID USERNAME NAME ISD VALUE

---- ------------ ---------------------------------------- --- ----------

149 JKOOPMANN parallel_execution_enabled YES true

149 JKOOPMANN optimizer_features_enable YES 10.1.0

149 JKOOPMANN cpu_count YES 2

149 JKOOPMANN active_instance_count YES 1

149 JKOOPMANN parallel_threads_per_cpu YES 2

149 JKOOPMANN hash_area_size YES 131072

149 JKOOPMANN bitmap_merge_area_size YES 1048576

149 JKOOPMANN sort_area_size YES 65536

149 JKOOPMANN sort_area_retained_size YES 0

Optimizer environment settings for Executing SQL

This is YOUR environment

SESSION Statistics


Up to now it has been “REAL-TIME” monitoring

The Good Old Days

� Catching a session waiting on a resource was literally hit and miss.

� DBAs would sit in front of the terminal screen and continually hit the ENTER key to watch activity in the V$SESSION_WAIT view trying to get a glimpse of a bottleneck.

� This in itself was a very tedious task

� Paranoia would set in (was I going to miss something)

Not So Long Ago

� DBAs very quickly got smarter and started to sample the data in the V$SESSION_WAIT table.

� They would write it out to another table or dump it to an external list file.

� This was fine but the overhead was high

Does Anyone Really Monitor Databases Like THIS Any More

� We NOW use or build our own monitoring tools to simulate resource capturing

?.?

8.0

7.1

Merging SYSTEM and SESSION Statistics


Throughput of our workload is all that matters

• What workload is in our system (SQL)

• When did it happen

• How long did it happen

• What resources where consumed

• How much resources where consumed

• To Whom did it happen

• How was the user effected

The Solution

• Proper mapping of resources to workload

Things to Overcome



� SYSTEM

HIGH level statistics have been global in nature and do not give the granularity needed to tune for throughput.

� SESSION

Low level statistics have been too granular and we have not had the ability to tie them to true workloads submitted to our systems.

� The MERGE

Your ability as a DBA/Developer to detect who/what is accessing the database, the SQL being executed, and the exact resources consumed over a period of time is paramount in your ability to properly manage and tune your database.

Why Do We Care



SQL is being executed from sqlplusO/S, DB, Session defined user

Change SQL, Application or tune resource

SQL is coming from two machinesTop SQL is sorted to top

Research resource consumed

(row cache lock)

This SQL statement is consuming 29.14 minutes across all sessions

SQL HASH VALUE

Look at SQL through Hash Value

(1245814300)

Four sessions are executing this SQL statement

Time Slice

Action PlanTo NoticeDefined Connection


New top SQL & resource to work onO/S, DB, Session defined user

Almost complete removal of resource (row cach lock)

Top SQL is sorted to top

Research resource consumed

(db file sequential read)

Total Resource for SQL (124581430) is under 10 minutes

SQL HASH VALUE

Look at New SQL through Hash Value (1195313771)

Our tuning of SQL (124581430) paid off

Time Slice

Action PlanTo NoticeDefined Connection


The Good Old Days

� Catching a session waiting on a resource was literally hit and miss.

� DBAs would sit in front of the terminal screen and continually hit the ENTER key to watch activity in the V$SESSION_WAIT view trying to get a glimpse of a bottleneck.

� This in itself was a very tedious task

� Paranoia would set in (was I going to miss something)

Not So Long Ago

� DBAs very quickly got smarter and started to sample the data in the V$SESSION_WAIT table.

� They would write it out to another table or dump it to an external list file.

� This was fine but the overhead was high

Times Are Changing

� Oracle is starting to listen to what vendors have been providing for years

� Oracle may have given us a better mousetrap for wait events

‘True’ Session Wait Activity

True Session Wait Activity

10g

8.0

7.1


To The Rescue

� Oracle samples statistical data through kernel code for V$SESSION_WAIT type statistics

� Stores the statistics in a rotating buffer space, 2 Meg per CPU

� Access these statistics through V$ACTIVE_SESSION_HISTORY

� One row of sampled activity for each session that was active

� As this buffer gets full because of the activity on the system, Oracle will move the captured statistics to disk as part of the Automatic Workload Repository (AWR) snapshot mechanism and it will now be available through the DBA_HIST_ACTIVE_SESS_HISTORY view.

� Depending on the activity of your system you may need to go to both views

� We can go back in time and look at the true cause of performance bottlenecks

Warning :

� Statistics may be lost if the buffer rotates before the AWR snapshot mechanism kicks in.

� The snapshot mechanism only takes a sampling of the data in $ACTIVE_SESS_HISTORY

V$ACTIVE_SESSION_HISTORY


All you mice out there, Tom & Jerry – Watch Out! ………well…..….sort of


SELECT active_session_history.event,

SUM(active_session_history.wait_time +

active_session_history.time_waited) ttl_wait_time

FROM v$active_session_history active_session_history

WHERE active_session_history.sample_time

BETWEEN TO_DATE('20050208:0540','YYYYMMDD:HH24MI')

AND TO_DATE('20050208:0550','YYYYMMDD:HH24MI')

GROUP BY active_session_history.event

ORDER BY 2 desc

EVENT TTL_WAIT_TIME

------------------------------ -------------

log file switch completion 2673862

row cache lock 1934383

log file parallel write 1072568

log file sequential read 715168

control file sequential read 429337

db file sequential read 229237

db file parallel write 168395

latch: redo allocation 18783

db file scattered read 14254

buffer busy waits 7624

What resource is/was currently in high demand

SYSTEM_EVENT type Statistics for the last 30 minutes (timed based statistics)



SELECT active_session_history.session_id, dba_users.username,



FROM v$active_session_history active_session_history,

dba_users




AND active_session_history.user_id = dba_users.user_id

GROUP BY active_session_history.session_id, dba_users.username

ORDER BY 3 DESC

SESSION_ID USERNAME TTL_WAIT_TIME

---------- ------------------------------ -------------

142 JKOOPMANN 1656292





What user is/was waiting the most?

SESSTAT type Statistics for last 30 minutes, Who/What is my hog at a particular time



SELECT active_session_history.user_id,

dba_users.username,

sqlarea.sql_text,




v$sqlarea sqlarea,

dba_users




AND active_session_history.sql_id = sqlarea.sql_id

AND active_session_history.user_id = dba_users.user_id

GROUP BY active_session_history.user_id,sqlarea.sql_text, dba_users.username

ORDER BY 4

USER_ID User SQL_TEXT TTL_WAIT_TIME

------- --------- ---------------------------------------------- -------------

142 JKOOPMANN select workseq.nextval into transnbr from dual 823023

What SQL is “currently” using the most resources?

Just Plain New (No more FALSE top 10 SQL hogs from V$SQLAREA)



SELECT dba_objects.object_name,

dba_objects.object_type,

active_session_history.event,




dba_objects




AND active_session_history.current_obj# = dba_objects.object_id

GROUP BY dba_objects.object_name, dba_objects.object_type,

active_session_history.event

ORDER BY 4 DESC

OBJECT_NAME OBJECT_TYPE EVENT TTL_WAIT_TIME

------------------------------ ------------------- ------------------------------ -------------

TRANS_LOG TABLE log file switch completion 1990217

TRANS_LOG TABLE row cache lock 1579727

TRANS_LOG TABLE latch: library cache 65325

TRANS_LOG TABLE db file sequential read 25533

TRANS_LOG TABLE enq: TX - contention 24870

What object is causing the highest resource waits

Just Plain New (much better segment level statistics)



V$SESSION

Oracle Session Tracing

Identifier to represent the client sessionMonitor an individual or group of usersUsed to initiate traces and statistical gathering

CLIENT_IDENTIFIER

Name to represent the action being performed by the module.Monitor resources used by statement being executedUsed to initiate traces and statistical gathering

ACTION

Name to represent the module or code being executed. Monitor resources used by section of codeUsed to initiate traces and statistical gathering

MODULE

Service name of the session and represents the database connected to.SERVICE_NAME

Serial number of the connected. SERIAL#

Identifier for the connected session.SID

DescriptionSession Variable

Get a handle on the globalization of sessions


Set ACTION


EXEC DBMS_APPLICATION_INFO.SET_ACTION (action_name);

EXEC DBMS_APPLICATION_INFO.SET_MODULE(module_name, action_name);

CREATE OR REPLACE PROCEDURE PROCX AS

v_module_name varchar2(64);

v_action_name varchar2(64);

BEGIN

DBMS_APPLICATION_INFO.SET_MODULE(

module_name => 'MyModuleName',

action_name => 'MyActionName');

DBMS_APPLICATION_INFO.READ_MODULE(v_module_name, v_action_name);

DBMS_OUTPUT.PUT_LINE('Module : '||v_module_name);

DBMS_OUTPUT.PUT_LINE('Action : '||v_action_name);

DBMS_APPLICATION_INFO.SET_MODULE(NULL,NULL);

END;

/

SQL> EXEC PROCX

Module : MyModuleName

Action : MyActionName

Set MODULE & ACTION

Your Current MODULE & ACTION


Set your CLIENT_IDENTIFIER


EXEC DBMS_SESSION.SET_IDENTIFIER(v_user_identifier);

SELECT SYS_CONTEXT('USERENV','CLIENT_IDENTIFIER') CLIENT_IDENTIFIER FROM DUAL;

CLIENT_IDENTIFIER

------------------------------------

James?F.?Koopmann:PINEHORSE\FINE-ALE

EXEC DBMS_SESSION.CLEAR_IDENTIFIER

Check your CLIENT_IDENTIFIER

Clear your CLIENT_IDENTIFIER


Logon Trigger


CREATE OR REPLACE TRIGGER LOGON_TRIGGER

AFTER LOGON ON DATABASE

DECLARE

v_user_identifier varchar2(64);

BEGIN

DBMS_APPLICATION_INFO.SET_MODULE(

module_name => 'LOGON_TRIGGER',

action_name => 'SELECT FROM DUAL');

SELECT SYS_CONTEXT('USERENV', 'OS_USER')||':'||

SYS_CONTEXT('USERENV', 'HOST')

INTO v_user_identifier

FROM dual;

DBMS_SESSION.SET_IDENTIFIER(v_user_identifier);

dbms_lock.sleep(5);

DBMS_APPLICATION_INFO.SET_MODULE(NULL,NULL);

END;

/

Setting CLIENT_IDENTIFIER, MODULE & ACTION


V$SESSION After Setting MODULE & ACTION name


SELECT sid,

client_identifier,

action,

module

FROM V$SESSION

SID CLIENT_IDENTIFIER ACTION MODULE

---- ----------------------------------------- -------------------- ----------------

133 James?F.?Koopmann:PINEHORSE\FINE-ALE SELECT FROM DUAL LOGON_TRIGGER

135 James?F.?Koopmann:PINEHORSE\FINE-ALE mmc.exe

149 James?F.?Koopmann:PINEHORSE\FINE-ALE SQL*Plus

132 PAULANER\Administrator:PINEHORSE\PAULANER SQL*Plus

Proper setting of the ACTION and MODULE name are imperative for collecting

statistics around specific code functions and transactions. Once they are set you

can now begin getting those fine grain details about the area of code that is

performing poorly. Next time we start looking at how to actually pull out of

current sessions that fine grain information to zero in on where we need to

concentrate our tuning efforts.


Individual Session Activity History


SELECT session_id, client_id, event,

SUM(wait_time + time_waited) ttl_wait_time





GROUP BY session_id, client_id, event

ORDER BY 4 DESC

SESSION_ID CLIENT_ID EVENT TTL_WAIT_TIME

---------- ------------------------------------------ ------------------------------ -------------

142 James?F.?Koopmann:PINEHORSE\FINE-ALE log file switch completion 1221966

148 James?F.?Koopmann:PINEHORSE\FINE-ALE log file switch completion 734903

161 PAULANER\Administrator:PINEHORSE\PAULANER row cache lock 670669

140 PAULANER\Administrator:PINEHORSE\PAULANER log file switch completion 487042

140 PAULANER\Administrator:PINEHORSE\PAULANER row cache lock 442928

142 James?F.?Koopmann:PINEHORSE\FINE-ALE row cache lock 430928

148 James?F.?Koopmann:PINEHORSE\FINE-ALE row cache lock 389858

161 PAULANER\Administrator:PINEHORSE\PAULANER latch: library cache 31923

161 PAULANER\Administrator:PINEHORSE\PAULANER db file sequential read 25533

140 PAULANER\Administrator:PINEHORSE\PAULANER enq: TX - contention 24870

140 PAULANER\Administrator:PINEHORSE\PAULANER latch: library cache 21783

148 James?F.?Koopmann:PINEHORSE\FINE-ALE latch: library cache 16703

140 PAULANER\Administrator:PINEHORSE\PAULANER db file sequential read 14965

161 PAULANER\Administrator:PINEHORSE\PAULANER buffer busy waits 7616

148 James?F.?Koopmann:PINEHORSE\FINE-ALE read by other session 6820

140 PAULANER\Administrator:PINEHORSE\PAULANER latch: shared pool 4185

140 PAULANER\Administrator:PINEHORSE\PAULANER latch: undo global data 3090


Accumulated Wait Activity for User Defined Area


SELECT client_id, event,






GROUP BY client_id, event

ORDER BY 3 DESC

CLIENT_ID EVENT TTL_WAIT_TIME

------------------------------------------ ------------------------------ -------------

James?F.?Koopmann:PINEHORSE\FINE-ALE log file switch completion 1956869

PAULANER\Administrator:PINEHORSE\PAULANER row cache lock 1113597

James?F.?Koopmann:PINEHORSE\FINE-ALE row cache lock 820786

PAULANER\Administrator:PINEHORSE\PAULANER log file switch completion 487042

PAULANER\Administrator:PINEHORSE\PAULANER latch: library cache 53706

PAULANER\Administrator:PINEHORSE\PAULANER db file sequential read 40498

PAULANER\Administrator:PINEHORSE\PAULANER enq: TX - contention 24870

James?F.?Koopmann:PINEHORSE\FINE-ALE latch: library cache 19672

PAULANER\Administrator:PINEHORSE\PAULANER buffer busy waits 7616

James?F.?Koopmann:PINEHORSE\FINE-ALE read by other session 6830

PAULANER\Administrator:PINEHORSE\PAULANER latch: shared pool 4426

PAULANER\Administrator:PINEHORSE\PAULANER latch: undo global data 3090

PAULANER\Administrator:PINEHORSE\PAULANER latch free 2765

James?F.?Koopmann:PINEHORSE\FINE-ALE latch: enqueue hash chains 5

James?F.?Koopmann:PINEHORSE\FINE-ALE latch: cache buffers chains 5

PAULANER\Administrator:PINEHORSE\PAULANER latch: row cache objects 4


What Code consumes most resources


SELECT module, action,






GROUP BY module,action

ORDER BY 3 DESC

MODULE ACTION TTL_WAIT_TIME

------------------------------ --------------- -------------

LoadTransx INSERT 2627984

GetTransactionNumber SELECTSeqNbr 1914840

GetTranssxssageumber INSERT 1300


DBMS_MONITOR Package


SESSION_TRACE_EISABLE

• Session must exist• Traces only a given session• Enables / Disables a trace for the instance submitter is connected to.

Enable / Disable Tracing for a session identifier (SID)

SESSION_TRACE_ENABLE

SERV_MOD_ACT_TRACE_DISABLE

• Trace data may be written to many trace files as the trace may effect multiple connected sessions with the same Service Name, Module, or Action.

Enable / DisableTracing for (Service Name/MODULE/ACTION) combination.

SERV_MOD_ACT_TRACE_ENABLE

SERV_MOD_ACT_STAT_DISABLE

• Statistics can be seen through V$SERV_MOD_ACT_STATS.

Enable / DisableStatistics gathering for (Service Name/MODULE/ACTION) combination.

SERV_MOD_ACT_STAT_ENABLE

CLIENT_ID_TRACE_DISABLE

• Trace data may be written to many trace files as the trace may effect multiple connected sessions with the same client identifier.

Enable / DisableTracing for A given Client Identifier

CLIENT_ID_TRACE_ENABLE

CLIENT_ID_STAT_DISABLE

• Statistics can be seen through V$CLIENT_STATS.Enable / DisableStatistics gathering for A given Client Identifier

CLIENT_ID_STAT_ENABLE

NotesDescriptionProgram

Remember to DISABLE what you ENABLE


Determine Connected Sessions for Tracing


SELECT sid, serial#,

client_identifier,

service_name,

action,

module

FROM V$SESSION

SID SERIAL# CLIENT_IDENTIFIER SERVICE_NAME ACTION MODULE

--- ------ ----------------------------------------- -------------- ------------- --------------------

161 118 PAULANER\Administrator:PINEHORSE\PAULANER pinehorse.com INSERT LoadTransx

142 1137 James?F.?Koopmann:PINEHORSE\FINE-ALE pinehorse.com SELECTSeqNbr GetTransactionNumber

148 1306 James?F.?Koopmann:PINEHORSE\FINE-ALE pinehorse.com SELECTSeqNbr GetTransactionNumber

140 308 PAULANER\Administrator:PINEHORSE\PAULANER pinehorse.com BuildTransx BuildLogMessage


DBMS_MONITOR Package


SERV_MOD_ACT_STAT_DISABLE

DBMS_MONITOR.SERV_MOD_ACT_STAT_ENABLE(service_name, module_name, action_name);

Action_name, may be an empty field if not defined for the session. •Use DBMS_MONITOR.ALL_ACTIONS variable to reference ALL sessions that have an action_name defined. •To reference ALL sessions that do not have this variable defined, use NULL.•The contents of this field is actually ‘###ALL_ACTIONS’ and you should avoid naming any actions or module names with this.

SERV_MOD_ACT_STAT_ENABLE

CLIENT_ID_STAT_DISABLE

DBMS_MONITOR.CLIENT_ID_STAT_ENABLE(client_identifier);CLIENT_ID_STAT_ENABLE

Example How to EnableProgram

Enable statistics gathering for CLIENT_IDENTIFIER.EXEC DBMS_MONITOR.CLIENT_ID_STAT_ENABLE(‘PAULANER\Administrator:PINEHORSE\PAULANER’);

EXEC DBMS_MONITOR.CLIENT_ID_STAT_ENABLE(‘James?F.?Koopmann:PINEHORSE\FINE-ALE’);


DBA_ENABLED_AGGREGATIONS


SELECT * FROM DBA_ENABLED_AGGREGATIONS ;

AGGREGATION_TYPE PRIMARY_ID QUALIFIER_ID1 QUALIFIER_ID2

--------------- ----------------------------------------- -------------------- ---------------

CLIENT_ID James?F.?Koopmann:PINEHORSE\FINE-ALE

CLIENT_ID PAULANER\Administrator:PINEHORSE\PAULANER

SERVICE_MODULE pinehorse.com BuildLogMessage

SERVICE_MODULE pinehorse.com GetTransactionNumber

SERVICE_MODULE pinehorse.com LoadTransx

The action nameQUALIFIER_ID2

The module nameQUALIFIER_ID1

This is the CLIENT_IDENTIFIER or SERVICE_NAME in the callPRIMARY_ID

This is the type of statistical aggregation being done. This relates to the actual procedure called in the DBMS_MONITOR package. In Listing 1 I we have called the CLIENT_ID_STAT_ENABLE and SERV_MOD_ACT_STAT_ENABLE procedures

AGGREGATION_TYPE

DescriptionColumn


Views that Contain Statistical Information


•This view provides an aggregated view for the combination of SERVICE_NAME, MODULE, and ACTION you have defined when you enabled aggregated statistics.Just be careful to name these aggregates appropriately so that you can quickly determine where bottlenecks reside.

V$SERV_MOD_ACT_STATS

•Provides a reduced set of statistics that can be used to determine how well an instance is performing for the requests made upon it. •This is typically the SID_NAME but beware it may be different if you are not connecting through TNS.

V$SERVICE_STATS

•If you have enabled any statistics for a CLIENT_IDENTIFIER you will see the aggregated statistics for that CLIENT_IDENTIFIER in this view that are currently active. •These statistics are only good for current activity and troubleshooting and thus should only be used for getting a glimpse of what clients are consuming the most resources. •Very valuable for a quick current view but if you need to drill to a particular client you will end up going to V$ACTIVE_SESSION_HISTORY.

V$CLIENT_STATS

•This view is just a historical representation of the V$ACTIVE_SESSION_HISTORY view above. While it is good for some historical information, be warned that it does not contain all the collected statistics that were captured in the V$ACTIVE_SESSION_HISTORY view.

DBA_HIST_ACTIVE_SESS_HISTORY

•The V$ACTIVE_SESSION_HISTORY view is a holding area for sampled session data performed on your behalf from the Oracle engine. This data is sampled once per second and is a great resource for determining where the true bottleneck lies in your system. •Use this view in conjunction with setting the CLIENT_IDENTIFIER, ACTION, and MODULE to aggregate (GROUP BY) and find the largest consumers of resources within your system.

V$ACTIVE_SESSION_HISTORY

DescriptionTable


DBMS_MONITOR Package (Trace Control)


SESSION_TRACE_DISABLE

DBMS_MONITOR.SESSION_TRACE_ENABLE(session_id, serial_number, waits, binds)session_id, Must provide. If just a session_id is given than all serial numbers will be traced. If session_id and serial_number are NULL than you trace your own current session.

SESSION_TRACE_ENABLE

SERV_MOD_ACT_TRACE_DISABLE

DBMS_MONITOR.SERV_MOD_ACT_TRACE_ENABLE(service_name, module_name, action_name, waits, binds, instance_name);

•Use DBMS_MONITOR.ALL_ACTIONS variable to reference ALL sessions that have an action name defined. •To reference ALL sessions that do not have this variable defined, use NULL.•The contents of this field is actually ‘###ALL_ACTIONS’ and you should avoid naming any actions or module names with this.instance_name restricts tracing to the named instance_name.

SERV_MOD_ACT_TRACE_ENABLE

CLIENT_ID_TRACE_DISABLE

DBMS_MONITOR.CLIENT_ID_TRACE_ENABLE(client_id, waits, binds);waits : If TRUE, wait information is present in the trace.Binds : If TRUE, bind information is present in the trace.

CLIENT_ID_TRACE_ENABLE

Example How to EnableProgram

Enable tracing for CLIENT_IDENTIFIER with wait information but no bind informationEXECUTE DBMS_MONITOR.CLIENT_ID_TRACE_ENABLE(‘PAULANER\Administrator:PINEHORSE\PAULANER’,TRUE,FALSE);

EXECUTE DBMS_MONITOR.CLIENT_ID_TRACE_ENABLE(‘James?F.?Koopmann:PINEHORSE\FINE-ALE’,TRUE,FALSE);


DBA_ENABLED_TRACES


SELECT * FROM DBA_ENABLED_TRACES ;

TRACE_TYPE PRIMARY_ID QULIFY1 QULIFY2 WAITS BINDS INSTANCE_NAME

---------- ----------------------------------------- ------- ------- ----- ----- ----------

CLIENT_ID PAULANER\Administrator:PINEHORSE\PAULANER TRUE FALSE

CLIENT_ID James?F.?Koopmann:PINEHORSE\FINE-ALE TRUE FALSE

Instance name for tracing restricted to named instances INSTANCE_NAME

Indicates whether binds are traced (TRUE) or not (FALSE) BINDS

Indicates whether waits are traced (TRUE) or not (FALSE) WAITS

The action nameQUALIFIER_ID2

The module nameQUALIFIER_ID1

This is the CLIENT_IDENTIFIER or SERVICE_NAME in the callPRIMARY_ID

Type of the trace: (CLIENT_ID, SERVICE, SERVICE_MODULE, SERVICE_MODULE_ACTION)NOT SESSION

TRACE_TYPE

DescriptionColumn


Where is My Trace File


USER_DUMP_DEST is the location on disk where Oracle will write out your enabled trace information.

SQL > SHOW PARAMETER user_dump_destNAME TYPE VALUE

------------------------------------ ----------- ------------------------------

user_dump_dest string D:\ORACLE\PRODUCT\10.1.0\ADMIN\LAGER\UDUMP

SQL > SELECT value FROM v$parameter WHERE name = ‘user_dump_dest’;VALUE

-----------------------------------

D:\ORACLE\PRODUCT\10.1.0\ADMIN\LAGER\UDUMP

SQL > ALTER SESSION SET TRACEFILE_IDENTIFIER = ‘SomeIdentifier;

Give Your Trace File Meaning


Part of a Trace File


Dump file d:\oracle\product\10.1.0\admin\lager\udump\lager_ora_162.trc

*** ACTION NAME:() 2005-02-08 05:29:13.515

*** MODULE NAME:(SQL*Plus) 2005-02-08 05:29:13.515

*** SERVICE NAME:(pinehorse.com) 2005-02-08 05:29:13.515

*** CLIENT ID:(PAULANER\Administrator:PINEHORSE\PAULANER) 2005-02-08 05:29:

*** SESSION ID:(161.20) 2005-02-08 05:29:13.515

=====================

PARSING IN CURSOR #1 len=18 dep=0 uid=64 oct=47 lid=64 tim=2985552493 hv=21

BEGIN work; END;

END OF STMT

PARSE #1:c=0,e=208,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=1,tim=2985552444

*** ACTION NAME:(SELECTSeqNbr) 2005-02-08 05:29:13.578

*** MODULE NAME:(GetTransactionNumber) 2005-02-08 05:29:13.578

=====================


SELECT WORKSEQ.NEXTVAL FROM DUAL

END OF STMT


EXEC #2:c=0,e=257,p=0,cr=0,cu=0,mis=0,r=0,dep=1,og=1,tim=2985571308

=====================


update seq$ set increment$=:2,minvalue=:3,maxvalue=:4,cycle#=:5,order$=:6,c

END OF STMT


EXEC #3:c=15625,e=790,p=0,cr=1,cu=2,mis=0,r=1,dep=2,og=4,tim=2985581702

STAT #3 id=1 cnt=1 pid=0 pos=1 obj=0 op='UPDATE (cr=1 pr=0 pw=0 time=592 u

FETCH #2:c=15625,e=15799,p=0,cr=1,cu=3,mis=0,r=1,dep=1,og=1,tim=2985587476

*** ACTION NAME:(INSERT) 2005-02-08 05:29:13.593

*** MODULE NAME:(LoadTransx) 2005-02-08 05:29:13.593

Can you say grep –i {search_pattern} *.trc


Syntax & Example for trcsess


trcsess [output = output_file_name]

[session = session_Id]

[clientid = client_Id]

[service = service_name]

[action = action_name]

[module = module_name]

[trace_files]

Example:Consolidate all trace files for everyone that has been in the Transaction Module (GetTransactionNumber).

C:\> trcsess output=GetTransactionNumber.trc module=GetTransactionNumber *.trc


What Can TKPROF Do


1. Formats all the cryptic information in a more readable form that is understandable for you and me.

2. Breaks out each statement executed during the trace period and presents various statistics that enable us to determine where bottlenecks lay and where we might spend our time tuning application code.

3. Can generate a SQL script that allows us to store the captured statistics into a database.

4. Will determine the explain plan for executed SQL statements.

5. Provides for summary as well as detail information for collected statistics


Syntax & Example for TKPROF


tkprof trace_file report_file

[waits = yes|no]

[sort = option]

[print = n]

[aggregate = yes|no]

[insert = filename3]

[sys = yes|no]

[table = schema.table]

[explain = user/password]

[record = filename4]

[width = n]

Example:Produce report for all users within the Transaction Module (GetTransactionNumber).

C:\> tkprof GetTransactionNumber.trc GetTransactionNumber.rpt


TKPROF Report


TKPROF: Release 10.1.0.2.0 - Production on Tue Feb 8 20:29:57 2005

Copyright (c) 1982, 2004, Oracle. All rights reserved.

Trace file: GetTransactionNumber.trc

Sort options: default

********************************************************************************

count = number of times OCI procedure was executed

cpu = cpu time in seconds executing

elapsed = elapsed time in seconds executing

disk = number of physical reads of buffers from disk

query = number of buffers gotten for consistent read

current = number of buffers gotten in current mode (usually for update)

rows = number of rows processed by the fetch or execute call

********************************************************************************

SELECT WORKSEQ.NEXTVAL FROM DUAL

call count cpu elapsed disk query current rows

------- ------ -------- ---------- ---------- ---------- ---------- ----------

Parse 4 0.01 0.00 0 0 0 0

Execute 85071 516.03 3221.43 27 122597 605469 0

Fetch 85067 111.60 175.19 0 54 85173 85063

------- ------ -------- ---------- ---------- ---------- ---------- ----------

total 170142 627.65 3396.63 27 122651 690642 85063

WOW! Just what I wanted


Tracing Enhancements


The world of tracing Oracle sessions has changed drastically with Oracle 10g.

Not so much the mechanisms but in the way we can initiate a trace for one session or a group of sessions.

We are now able to "tag" sessions as they are connected to Oracle and move through applications.

We can now accurately pinpoint where in the application a session is, the amount of resources being consumed, and more importantly if the session is having difficulty and is in need of tuning.

This is extremely important in a multi-tier environment where connection polling takes place and we would be lost if it where not for these new tracing features.


Zeroing in on Performance in Oracle 10g

James F. KoopmannFounder & President

[email protected]

KoopmannZeroingInOnPerformanceInOracle10g

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