Oracle 10g Performance: chapter 04 new features

10g New Performance Features
1. Alerts
2. Metrics
3. AWR ( 7 days of history DBA_HIST_ )
4. Time Model
5. Wait Classes
6. Misc

Copyright 2006 Kyle Hailey #.1

Alerts Set
select
metrics_name alert, In 10g, alerts are
warning_operator op, managed in the
warning_value warn ,
database
object_name obj
from
dba_thresholds;

ALERT OP WARN
----------------------------------- ---- ------ OBJ
-------
Average Users Waiting Counts GT 10
Concurrency
Blocked User Session Count GT 0
CPU Time Per User Call GE 8000 db3
Logons Per Sec GE 100
Session Limit % GT 90
Tablespace Space Usage GE 85
Tablespace Space Usage GE 90 SYSTEM

Alerts Outstanding

select
reason,
object_type type,
object_name name
from
dba_outstanding_alerts;

REASON TYPE NAME
------------------------------------------ ----------- -------
Tablespace [PERFSTAT] is [97 percent] full TABLESPACE PERFSTA


Alerts Setting
DBMS_SERVER_ALERT.SET_THRESHOLD(
METRICS_ID => DBMS_SERVER_ALERT.CPU_TIME_PER_CALL,
WARNING_OPERATOR => DBMS_SERVER_ALERT.OPERATOR_GE,
dbms_server_alert.set_threshold(
WARNING_VALUE
METRICS_ID => '8000',
=> dbms_server_alert.tablespace_pct_full,
CRITICAL_OPERATOR
WARNING_OPERATOR => DBMS_SERVER_ALERT.OPERATOR_GE,
=> dbms_server_alert.operator_ge,
CRITICAL_VALUE
WARNING_VALUE => '10000',
=> 90,
OBSERVATION_PERIOD
CRITICAL_OPERATOR => 1,
=> dbms_server_alert.operator_ge,
CONSECUTIVE_OCCURRENCES => 2,
CRITICAL_VALUE => 99,
INSTANCE_NAME
OBSERVATION_PERIOD => 'SID',
=> 1,
OBJECT_TYPE
CONSECUTIVE_OCCURRENCES => DBMS_SERVER_ALERT.OBJECT_TYPE_SERVICE,
=> 1,
OBJECT_NAME
INSTANCE_NAME => 'SID')
=> null,
OBJECT_TYPE => dbms_server_alert.object_type_tablespace,
OBJECT_NAME => 'SYSTEM');

http://www.psoug.org/reference/dbms_serv_alert.html

9i
10g Metrics
DBA_HIST_SQLSTAT

v$sql
v$sql
SQL
Waits
v$system_event
v$system_event
V$eventmetric
V$waitclassmetric

V$session_wait

Metrics V$session_event

V$sesstat

v$sysstat
v$systat
Stats v$session
v$session
Sessions V$sessmetric

V$sysmetric


Metrics
 What inspired Metrics?
 Alerting

 But … metrics make our lives easier
 Old statistics were cumulative
 Old statistics lacked history

Question:
What is the IO on the system right now?

First Tedious Step

Select value from v$sysstat
where name=‘physical reads’;

VALUE

1,533,787

Not much help …Why? Let see …


This tells you … Nothing
GOOD BAD

1,533,787

30 minutes

IO’s

30 minutes

time time


Need to do MATH to find Out

Take value at time A
Take value at time B
Delta = (B-A)
or
Rate = (B-A)/elapsed time


Methods
 Oracle 6 Utlbstat.sql/Utlestat.sql
 Creates tables, inserts, deletes
 Oracle 8 introduced Statspack
 Improvement,but needs to be set up and administered
(by guess who)
 Oracle 10 introduces Metrics (and AWR & OEM)

Overkill to run statspack for one or two statistics,
now 10g gives us metric tables


Performance Metric Deltas
Kinds of Metric Tables

1. Metric – current
2. Metric History – last hour

Current Deltas History of Values over last hour
V$EVENTMETRIC V$FILEMETRIC_HISTORY
V$FILEMETRIC V$SYSMETRIC_HISTORY
V$SESSMETRIC V$SERVICEMETRIC_HISTORY
V$SERVICEMETRIC V$WAITCLASSMETRIC_HISTORY
V$SYSMETRIC
V$SYSMETRIC_SUMMARY
V$WAITCLASSMETRIC

#.11
Copyright 2006 Kyle Hailey

Metrics
 Intervals  Calculations
 15 second  Deltas
 60 second  Rates
 10 minutes - file IO  per second
 30 minutes - sql
 per transaction
 Ratios
 Percentages


Metric Tables
Wait Events
 V$EVENTMETRIC (60 secs )
 V$WAITCLASSMETRIC (60 secs)

Statistics
 V$SESSMETRIC (15 secs Deltas)
 V$SYSMETRIC (15 and 60 secs deltas)

Files
 V$FILEMETRIC ( 10 minutes)

SQL
 DBA_HIST_SQLSTAT


Answer at your fingertips
GOOD BAD

3 IO/sec
X
1,533,787 513 IO/sec

30 minutes

IO’s

30 minutes

time time


Now What’s the IO?

Select VALUE , METRIC_UNIT
from v$sysmetric
where metric_name='Physical Reads Per Sec‘;

VALUE METRIC_UNIT INTSIZE_CSEC
654.6736 Reads Per Second 5959
134.9835 Reads Per Second 1515

Avg IO per sec for the last 15 and 60 secs


v$sysmetric
desc v$sysmetric
BEGIN_TIME
END_TIME
INTSIZE_CSEC – interval value in 1/100sec
GROUP_ID
METRIC_ID
METRIC_NAME
VALUE
METRIC_UNIT

Attention: metric_names are different from v$sysstat


v$sysmetric 15 Secs
Per Sec and Per Transaction
Physical Reads
Buffer Cache Hit Ratio Physical Writes
Memory Sorts Ratio Physical Reads Direct
Execute Without Parse Ratio Redo Generated
Logons
Soft Parse Ratio
User Calls
Database CPU Time Ratio Logical Reads
Library Cache Hit Ratio Redo Writes
Shared Pool Free % Total Table Scans
Full Index Scans
Txns Per Logon
DB Block Gets
Consistent Read Gets
Per Sec DB Block Changes
Consistent Read Changes
User Transaction Per Sec
Executions


v$sysmetric 60 Sec
Buffer Cache Hit Ratio Current Logons Count
Memory Sorts Ratio Current Open Cursors Count
Redo Allocation Hit Ratio User Limit %
User Commits Percentage SQL Service Response Time
User Rollbacks Percentage Database Wait Time Ratio
Cursor Cache Hit Ratio Database CPU Time Ratio
Rows Per Sort Row Cache Hit Ratio
Execute Without Parse Ratio Row Cache Miss Ratio
Soft Parse Ratio Library Cache Hit Ratio
User Calls Ratio Library Cache Miss Ratio
Global Cache Average CR Get Time Shared Pool Free %
Global Cache Average Current Get Time PGA Cache Hit %
Global Cache Blocks Corrupted Process Limit %
Global Cache Blocks Lost Session Limit %
Txns Per Logon


v$sysmetric 60 Sec
Per Second and Transaction
Per Sec Physical Reads Disk Sort
Physical Writes Enqueue Timeouts
User Commits Physical Reads Direct Enqueue Waits
User Rollbacks Physical Writes Direct Enqueue Deadlocks
User Transaction Physical Reads Direct Lobs Enqueue Requests
Physical Writes Direct Lobs DB Block Gets
DBWR Checkpoints
Redo Generated Consistent Read Gets
Background Checkpoints
Logons DB Block Changes
Network Traffic Volume Open Cursors Consistent Read Changes
User Calls CPU Usage
Per Transaction Recursive Calls CR Blocks Created
Logical Reads CR Undo Records Applied
Response Time Redo Writes User Rollback Undo Records
Long Table Scans Applied
Total Table Scans Leaf Node Splits
Full Index Scans Branch Node Splits
Total Index Scans PX downgraded 1 to 25%
Total Parse Count PX downgraded 25 to 50%
Hard Parse Count PX downgraded 50 to 75%
Parse Failure Count PX downgraded 75 to 99%
.

v$sessmetric

desc v$sessmetric
BEGIN_TIME
• Only 15 second
END_TIME Delta
INTSIZE_CSEC
SESSION_ID
SESSION_SERIAL_NUM
CPU
PHYSICAL_READS
PGA_MEMORY
HARD_PARSES
SOFT_PARSES
PHYSICAL_READ_PCT
LOGICAL_READ_PCT


Desc v$eventmetric

SQL> desc v$eventmetric
Name Type
---------------------------------- ------
BEGIN_TIME DATE
END_TIME DATE
INTSIZE_CSEC NUMBER
EVENT# NUMBER
EVENT_ID NUMBER
NUM_SESS_WAITING NUMBER
TIME_WAITED NUMBER
WAIT_COUNT NUMBER


Historical Metrics
We solved what’s happening now… but

 What if your problem happened 10 minutes ago?
 How do we get History?
 What happened in the past?


Metric History Tables
Last 60 minutes of history, in memory

v$sysstat
physical reads delta
delta
delta

delta

delta

delta

delta

60 secs 60 secs 60 secs 60 secs 60 secs 60 secs 60 secs


Metric History Tables

Last hour of statistics at your fingertips :
Statistics 3 minutes of 15 second
 V$SYSMETRIC_HISTORY deltas
 60 seconds for an hour
 3 minutes of 15 second

 File IO 60 minutes of 1 minute deltas
 V$FILEMETRIC_HISTORY
 10 minutes for an hour

 Waits
 V$WAITCLASSMETRIC_HISTORY
 60 seconds for an hour


What was IO 30 minutes ago?
Select
to_char(end_time,'DD-MON-YY HH24:MI'),
VALUE ,
METRIC_UNIT
from
v$sysmetric_history
where
METRIC_NAME = 'Physical Reads Per Sec' and
END_TIME < ( sysdate - (30/(24*60))) and
END_TIME > ( sysdate - (35/(24*60)))
order by end_time;
TO_CHAR(END_TIM VALUE METRIC_UNIT
08-JAN-08 11:38 118.65 Reads Per Second


V$FILEMETRIC_HISTORY
select
BEGIN_TIME,
FILE_ID,
PHYSICAL_READS
from
V$FILEMETRIC_HISTORY;

BEGIN_TI FILE_ID PHYSICAL_READS
04:12:16 1 208
04:12:16 2 600
Physical Reads
04:02:18 1 600
04:02:18 2 189 Broken down by
03:52:15 1 1922 file
03:52:15 2 2082
…


Metric Alerts
If Alerts fire on Metrics, then the deltas are kept in
historical table for 7 days by default

Statistics Not to be confused
 DBA_HIST_SYSMETRIC_HISTORY with the other metric
 DBA_HIST_SESSMETRIC_HISTORY
tables, these only
Waits have values when
 WAITCLASSMETRIC_HISTORY
alerts fire

File IO
 DBA_HIST_FILEMETRIC_HISTORY


Metrics Family of Tables
Stats Waits Files
Raw V$sysstat v$system_event v$fileio
v$event_histogram
v$system_wait_class

Now V$sysmetric v$eventmetric v$filemetric
V$SYSMETRIC v$waitclassmetric
V$SYSMETRIC_SUMMARY
V$SESSMETRIC
Session : v$sessmetric

V$sysmetric_history v$waitclassmetric_history v$filemetric_history
V$sysmetric_summary
1 Hour

DBA_HIST_WAITCLASSMETRIC_HISTORY DBA_HIST_FILEMETRIC_HISTORY
DBA_HIST_SYSMETRIC_HISTORY
7 days DBA_HIST_SESSMETRIC_HISTORY DBA_HIST_SQLSTAT
Alerts DBA_HIST_ DBA_HIST_SYSTEM_EVENT
only SYSMETRIC_SUMMARY


AWR
Automatic Workload Repository
 Statspack on Steroids
 More efficient than Statspack
 More in memory
 Less latching

 Keeps stats every hour
 Stores by default the last 7 days


Snapshoting
Done automatically out of the box, but can be run by hand:

BEGIN
DBMS_WORKLOAD_REPOSITORY.CREATE_SNAPSHOT ();
END;
/

dbms_workload_repository.drop_snapshot_range


DBA_HIST
DBA_HIST_DATABASE_INSTANCE DBA_HIST_RESOURCE_LIMIT
DBA_HIST_SNAPSHOT DBA_HIST_SHARED_POOL_ADVICE
- DBA_HIST_SNAP_ERROR ?DBA_HIST_SQL_WORKAREA_HSTGRM
- DBA_HIST_BASELINE DBA_HIST_PGA_TARGET_ADVICE
- DBA_HIST_WR_CONTROL ? (work load repository ?) DBA_HIST_INSTANCE_RECOVERY
- DBA_HIST_DATAFILE DBA_HIST_JAVA_POOL_ADVICE
DBA_HIST_FILESTATXS – only file number, no name DBA_HIST_THREAD - logswitches
- DBA_HIST_TEMPFILE -DBA_HIST_STAT_NAME
DBA_HIST_TEMPSTATXS – onl;y file number DBA_HIST_SYSSTAT
+DBA_HIST_SQLSTAT group by parent cursor plus DELTAs was (stats$sql_summary) -DBA_HIST_SYS_TIME_MODEL
DBA_HIST_SQLTEXT -DBA_HIST_OSSTAT_NAME
+DBA_HIST_SQL_SUMMARY – identify litterals (was stat$sql_statistics) -DBA_HIST_OSSTAT
DBA_HIST_SQL_PLAN DBA_HIST_PARAMETER_NAME
-DBA_HIST_SQLBIND DBA_HIST_PARAMETER
-DBA_HIST_SQLBIND_META - WRH$_SQL_BIND_METADATA
DBA_HIST_SQLBIND_META DBA_HIST_UNDOSTAT
-DBA_HIST_OPTIMIZER_ENV DBA_HIST_ROLLSTAT
-DBA_HIST_EVENT_NAME DBA_HIST_SEG_STAT
DBA_HIST_SYSTEM_EVENT DBA_HIST_SEG_STAT_OBJ – object name
DBA_HIST_BG_EVENT_SUMMARY – sum of backgrounds -DBA_HIST_METRIC_NAME
DBA_HIST_WAITSTAT -DBA_HIST_SYSMETRIC_HISTORY alert
DBA_HIST_ENQUEUE_STAT -DBA_HIST_SYSMETRIC_SUMMARY – max, min, avg standard
-DBA_HIST_LATCH_NAME deviation
DBA_HIST_LATCH -DBA_HIST_SESSMETRIC_HISTORY alert
DBA_HIST_LATCH_CHILDREN -DBA_HIST_FILEMETRIC_HISTORY alert
DBA_HIST_LATCH_PARENT -DBA_HIST_WAITCLASSMET_HISTORY alert
DBA_HIST_LATCH_MISSES_SUMMARY – summed over parent latch DBA_HIST_DLM_MISC
DBA_HIST_LIBRARYCACHE -DBA_HIST_RCVRY_FILE_DEST_STAT
DBA_HIST_DB_CACHE_ADVICE -DBA_HIST_RMAN_PERFORMANCE
DBA_HIST_BUFFER_POOL_STAT -DBA_HIST_ACTIVE_SESS_HISTORY – every 10th point from
DBA_HIST_ROWCACHE_SUMMARY – summed over rowcache entries v$active_session_history
DBA_HIST_SGA -DBA_HIST_TABLESPACE_STAT
DBA_HIST_SGASTAT -DBA_HIST_LOG
DBA_HIST_PGASTAT New in 10g DBA_HIST_MTTR_TARGET_ADVICE
-DBA_HIST_TBSPC_SPACE_USAGE - ?


Retention and Interval
Defaults:
 Hourly snapshots
 7 days saved

SELECT retention, snap_interval FROM wrm$_wr_control;

RETENTION SNAP_INTERVAL
+00007 00:00:00.0 +00000 01:00:00.0
Minutes
exec dbms_workload_repository.modify_snapshot_settings(14*24*60,30);

RETENTION SNAP_INTERVAL
+00014 00:00:00.0 +00000 00:30:00.0

AWR RPT
@?/rdbms/admin/awrrpt.sql

 Creates Report File
 Similar to STATSPACK report
 More efficient and more data
 HTML or TEXT
SELECT * FROM TABLE(
dbms_workload_repository.awr_report_text(
(select dbid from v$database),
1,
124, -- begin id
125 -- end id ))

AWR Report

1) General info
1) General info 11) Advisories 12) Buffer Pool Stats
12) Buffer Pool Stats
11) Advisories
2) Load Profile
2) Load Profile 1) Buffer pool 13) Wait Stats
13) Wait Stats
1) Buffer pool
3) Wait Events
3) Wait Events 2) PGA 1) Buffer Busy
1) Buffer Busy
2) PGA
4) OS Stats
4) OS Stats 3) Shared Pool 2) Enqueues
2) Enqueues
3) Shared Pool
5) Service Stats
5) Service Stats 4) SGA 12) Undo Stats
12) Undo Stats
4) SGA
6) Top SQL
6) Top SQL 5) Streams 13) Latch Stats
13) Latch Stats
5) Streams
7) SQL Text
7) SQL Text 6) Java 14) Segment Stats
14) Segment Stats
6) Java
8) Instance Statistic
8) Instance Statistic 15) Dictionary Stats
15) Dictionary Stats
9) I/O Stat
9) I/O Stat 16) Library Cache
16) Library Cache
10) Buffer Pool Stats
10) Buffer Pool Stats 17) Memory SGA/PGA
17) Memory SGA/PGA
18) Streams
18) Streams
19) Init.ora
19) Init.ora

Awr 1-13


AWR 14-26


AWR Diff
SELECT * FROM TABLE(
dbms_workload_repository.awr_diff_report_text(
1,
120,
121,
1,
122,
123)
);
Also : AWR_DIFF_REPORT_HTML


AWR Diff Report in OEM

NOTE: Package
AWR_DIFF_REPORT_HTML
Is different from OEM
Its just a tabular output


Also, ADDM report by Hand

select dbms_advisor.get_task_report(task_name)
from dba_advisor_tasks
where task_id = (
select max(t.task_id)
from dba_advisor_tasks t,
dba_advisor_log l
where t.task_id = l.task_id and
t.advisor_name = 'ADDM' and
l.status = 'COMPLETED');

Set long 100000


Important AWR Tables

 DBA_HIST_SQLSTAT
 SQL deltas
 DBA_HIST_SEG_STAT
 Segment deltas
 DBA_HIST_SYSMETRIC_SUMMARY
 Stats, max, min, avg
 Trending
 DBA_HIST_ACTIVE_SESS_HISTORY
 ASH
 DBA_HIST_SYSTEM_EVENT
 Waits
dba_hist_sqltext – get sql text from AWR


DBA_HIST_SNAPSHOT

SQL> desc DBA_HIST_SNAPSHOT
Name Type
------------------- -----------------------
SNAP_ID NUMBER
DBID NUMBER
INSTANCE_NUMBER NUMBER
STARTUP_TIME TIMESTAMP(3)
BEGIN_INTERVAL_TIME TIMESTAMP(3)
END_INTERVAL_TIME TIMESTAMP(3)
FLUSH_ELAPSED INTERVAL DAY(5) TO SECOND(1)
SNAP_LEVEL NUMBER
ERROR_COUNT NUMBER


DBA_HIST_SQLSTAT
SNAP_ID FETCHES_DELTA
DBID END_OF_FETCH_COUNT_DELTA
INSTANCE_NUMBER SORTS_DELTA
SQL_ID EXECUTIONS_DELTA
PX_SERVERS_EXECS_DELTA
PLAN_HASH_VALUE
LOADS_DELTA
OPTIMIZER_COST
INVALIDATIONS_DELTA
OPTIMIZER_MODE PARSE_CALLS_DELTA
OPTIMIZER_ENV_HASH_VALUE DISK_READS_DELTA
SHARABLE_MEM BUFFER_GETS_DELTA
LOADED_VERSIONS ROWS_PROCESSED_DELTA
VERSION_COUNT CPU_TIME_DELTA
MODULE ELAPSED_TIME_DELTA
ACTION IOWAIT_DELTA
SQL_PROFILE CLWAIT_DELTA
APWAIT_DELTA
FORCE_MATCHING_SIGNATURE
CCWAIT_DELTA
PARSING_SCHEMA_ID
DIRECT_WRITES_DELTA
PARSING_SCHEMA_NAME PLSEXEC_TIME_DELTA
BIND_DATA JAVEXEC_TIME_DELTA


DBA_HIST_SEG_STAT
Gets reset every DB bounce
SQL> desc DBA_HIST_SEG_STAT PHYSICAL_WRITES_TOTAL
PHYSICAL_WRITES_DELTA
Name
PHYSICAL_READS_DIRECT_TOTAL
SNAP_ID PHYSICAL_READS_DIRECT_DELTA
DBID PHYSICAL_WRITES_DIRECT_TOTAL
INSTANCE_NUMBER PHYSICAL_WRITES_DIRECT_DELTA
TS# ITL_WAITS_TOTAL
OBJ# ITL_WAITS_DELTA
DATAOBJ# ROW_LOCK_WAITS_TOTAL
LOGICAL_READS_TOTAL ROW_LOCK_WAITS_DELTA
LOGICAL_READS_DELTA SPACE_USED_TOTAL
BUFFER_BUSY_WAITS_TOTAL SPACE_USED_DELTA
BUFFER_BUSY_WAITS_DELTA SPACE_ALLOCATED_TOTAL
DB_BLOCK_CHANGES_TOTAL SPACE_ALLOCATED_DELTA
DB_BLOCK_CHANGES_DELTA TABLE_SCANS_TOTAL
PHYSICAL_READS_TOTAL TABLE_SCANS_DELTA
PHYSICAL_READS_DELTA

DBA_HIST_SYSTEM_EVENT

SQL> desc DBA_HIST_SYSTEM_EVENT
Name Type
----------------------------------
SNAP_ID NUMBER
DBID NUMBER
INSTANCE_NUMBER NUMBER
EVENT_ID NUMBER
EVENT_NAME VARCHAR2(64)
WAIT_CLASS_ID NUMBER
WAIT_CLASS VARCHAR2(64)
TOTAL_WAITS NUMBER
TOTAL_TIMEOUTS NUMBER
TIME_WAITED_MICRO NUMBER

Cumulative Values – can use LAG function

Average Wait Times
select
btime,
(time_ms_end-time_ms_beg)/nullif(count_end-count_beg,0) avg_ms
from (
select
to_char(s.BEGIN_INTERVAL_TIME,'DD-MON-YY HH24:MI') btime,
total_waits count_end,
time_waited_micro/1000 time_ms_end,
Lag (e.time_waited_micro/1000)
(
OVER( PARTITION BY e.event_name ORDER BY s.snap_id) time_ms_beg,
Lag (e.total_waits)
(
OVER( PARTITION BY e.event_name ORDER BY s.snap_id) count_beg
from
DBA_HIST_SYSTEM_EVENT e,
DBA_HIST_SNAPSHOT s
where BTIME AVG_MS
s.snap_id=e.snap_id -------------------- ------------
and e.event_name= '&1' 08-JAN-08 01:00 1.017
order by begin_interval_time 08-JAN-08 02:00 .720
)
08-JAN-08 03:00 .621
order by btime;
08-JAN-08 04:00 1.747
08-JAN-08 05:00 1.046
08-JAN-08 06:00 1.444

ASH RPT

 @?/rdbms/admin/ashrpt
 Detailed report on top SQL, Sessions, Objects etc
 Run over SQL*Net with
select output
from table(dbms_workload_repository.ash_report_text(
1,
sysdate – 2/24,
sysdate – 1/24,
0)) ;

 Also ASH_REPORT_HTML


ASH RPT

1) General info
1) General info 9) Top SQL using literals
9) Top SQL using literals
2) Top User Events ***
2) Top User Events *** 10) Top Sessions ***
10) Top Sessions ***
3) Top Background Events
3) Top Background Events 11) Top Blocking Sessions
11) Top Blocking Sessions
4) Top Event P1/P2/P3 Values
4) Top Event P1/P2/P3 Values 12) Top Sessions running PQs
12) Top Sessions running PQs
5) Top Service/Module
5) Top Service/Module 13) Top DB Objects
13) Top DB Objects
6) Top Client IDs
6) Top Client IDs 14) Top DB Files
14) Top DB Files
7) Top SQL Command Types
7) Top SQL Command Types 15) Top Latches
15) Top Latches
8) Top SQL Statements ***
8) Top SQL Statements *** 16) Activity Over Time ***
16) Activity Over Time ***


ASH RPT HTML


Time Model
New concept
• DB Time

Time Model
Total time for all database calls
• cpu time SQL
Wait
• wait time
Metrics

Stats
Sessions


Time Model areas
 Total Time
 CPU
 Updated every 5 seconds
 Elapsed Time
 SQL execution
 Plsql execution (sql execute subtracted out)
 Java execution
 Connection time
 Probablythe most important as it points out problems with
too many logons/sec


Time Model Components
1) background elapsed time
2) background cpu time

1) DB time
2) DB CPU
2) connection management call elapsed time
2) sequence load elapsed time
2) sql execute elapsed time
2) parse time elapsed
3) hard parse elapsed time
4) hard parse (sharing criteria) elapsed time
5) hard parse (bind mismatch) elapsed time
3) failed parse elapsed time
4) failed parse (out of shared memory) elapsed time
2) PL/SQL execution elapsed time
2) inbound PL/SQL rpc elapsed time
2) PL/SQL compilation elapsed time
2) Java execution elapsed time


Total Time

DB CPU
DB Wait Time
DB CPU
~ DB Total Database
Wait
Time
Time Time Time
Parse
Elapsed
Time


Hard Parse Bind Mismatch

hard
parse
(bind
mismat
hard ch)
parse elapsed
hard (sharing time
parse criteria)
Parse elapse elapsed
time d time time
elapsed


Time Model Tables
Current cumulative values
 V$SYS_TIME_MODEL
 V$SESS_TIME_MODEL

AWR Snapshots of cumulative values
 DBA_HIST_SYS_TIME_MODEL

Tables show cumulative values. To find deltas, then need
to run AWR report (no time model metric tables  )


Wait Classes
 Administrative (39)  Configuration (20)
 switch logfile  log file size
 rebuild index  Enqueues: ST, HW, ITL
 Latch: redo copy,shared pool
 Application (11)  Idle (56)
 enqueues
sqlnet break/reset
 Network (25)


 Cluster (113)
 Commit (1)  System I/O (19)
 Log file Sync  Scheduler (6)
 Concurrency (12)  User I/O (12)
 Latches: cbc, lbc,


Lib cache locks
Buffer busy wait  Other (485)


Wait Class Tables

v$system_wait_class
 cumulative

v$waitclassmetric
 Current rates
v$waitclassmetric_history
 Hour of rates (60 second intervals)


Waits Metrics
Cumulative Current deltas Last Hour Last 7 days
Wait
v$system_wait_class
Classes v$waitclassmetric v$waitclassmetric_history dba_hist_
WAIT_CLASS_ID
BEGIN_TIME BEGIN_TIME waitclassmetric_history
WAIT_CLASS# END_TIME
END_TIME
WAIT_CLASS
INTSIZE_CSEC INTSIZE_CSEC Only gets populated with alerts
TOTAL_WAITS WAIT_CLASS_ID
WAIT_CLASS_ID
TIME_WAITED WAIT_CLASS#
WAIT_CLASS#
NUM_SESS_WAITING NUM_SESS_WAITING
v$event_name TIME_WAITED TIME_WAITED
EVENT# WAIT_COUNT WAIT_COUNT
EVENT_ID
NAME
PARAMETER1
PARAMETER2
PARAMETER3
WAIT_CLASS_ID
WAIT_CLASS#
WAIT_CLASS

Wait Events
v$system_event v$eventmetric dba_hist_system_event
BEGIN_TIME
EVENT END_TIME (Cumulative)
TOTAL_WAITS INTSIZE_CSEC
TOTAL_TIMEOUTS EVENT_ID No in memory history
NUM_SESS_WAITING
TIME_WAITED
TIME_WAITED
AVERAGE_WAIT WAIT_COUNT
TIME_WAITED_MICRO
EVENT_ID


Miscellaneous

 V$sqlstats
 Field naming conventions
 Wait Improvements
 Wait histograms
 Waits in v$session and v$sql
 Waits show the blocker
 Wait history of last 10 waits

 Services
 Client Id


v$sqlstats
 More efficient than v$sql or v$sqlarea
 Uses less CPU
 Faster
 Skips many of the latch gets that v$sql does
 Uses Mutexes instead of some latches


Event and Stat Fields Names
 Names
SQL
 Event
 Statistic SQL_ID new hash
 Waitclass HASH_VALUE still there
 Ids
 Event#
 Statistic#
 Waitclass#

 Name Hash
 Event_id
 Statistic_id
 Waitclass_id


Wait Histograms

V$event_histogram
 1ms to 1 hour buckets
 23 buckets
 < 1 ms, < 2 ms, < 4 ms, < 8 ms, ..., < 2^22
ms


Waits in v$session

 V$session exposes all the fields from v$session_wait
SEQ# NUMBER
EVENT# NUMBER
EVENT VARCHAR2(64)
P1TEXT VARCHAR2(64)
P1 NUMBER
P1RAW RAW(4)
P2TEXT VARCHAR2(64)
P2 NUMBER
P2RAW RAW(4)
P3TEXT VARCHAR2(64)
P3 NUMBER
P3RAW RAW(4)
WAIT_CLASS_ID NUMBER
WAIT_CLASS# NUMBER
WAIT_CLASS VARCHAR2(64)
WAIT_TIME NUMBER
SECONDS_IN_WAIT NUMBER
STATE VARCHAR2(19)


Waits in V$SQL

 SQL_FULLTEXT
 SQL_ID
 FETCHES
 END_OF_FETCH_COUNT
 DIRECT_WRITES
 CONCURRENCY_WAIT_TIME
 APPLICATION_WAIT_TIME
 CLUSTER_WAIT_TIME
 USER_IO_WAIT_TIME
 PLSQL_EXEC_TIME
 JAVA_EXEC_TIME
 CPU_TIME
 ELAPSED_TIME


Waits show Blocking Session

V$session. BLOCKING_SESSION -> can build a
wait tree:


Services
 Services is a new way to measure resource usage and
statistics. A session is associated with a services when the
session connects to the database via the listener.
 DBMS_SERVICE.CREATE_SERVICE


Setting up Services
jdbc:oracle:thin:@//server:1521/SERVICE_NAME
dbms_service.CREATE_SERVICE('ora10a',‘A');
dbms_service.START_SERVICE ('ora10a');
-- dbms_service.STOP_SERVICE ('ora10a');
-- dbms_service.DELETE_SERVICE('ora10a');
Name
tnsA = tracked
(DESCRIPTION = tnsnames.ora
(ADDRESS_LIST =
in OEM
(ADDRESS = (PROTOCOL = TCP)
(HOST = kylehpd)(PORT = 1521)) ) Sqlplus un/pw@tnsA
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = A)
) )
lsnrctl services
Service "A" has 1 instance(s).
Instance "v10g", status READY, has 1 handler(s) for this service...
Handler(s):
"DEDICATED" established:0 refused:0 state:ready

Services in OEM

Enable Trace
By Service

View doesn’t work

Client Id
 Setting Client ID
dbms_session.set_identifier(client_id)

 Enabling trace for a client ID
dbms_monitor.client_id_trace_enable
(client_id, TRUE, FALSE)

 Enabling statistics aggregation by client id
dbms_monitor.client_id_stat_enable(client_id)

 Script to Extract Client Trace
Trcsess output=<name> client_id=<name> *


Session Dedicated
Scott John Sue Mike Randy Tim Mary

Oracle
S1 S2 S3 S4 S4 S5 S6
Sessions
Oracle Database Host


Session Dedicated trace

SQL_TRACE=TRUE

Oracle
S1 S2 S3 S4 S4 S5 S6
Sessions


Session Pooling trace

APP
Server
1
S1, sql_trace=true

Oracle
S1 S2 S3 S4 S4 S5 S6 S7
Sessions


Session Pooling


Set client_id =
SCOTT
dbms_monitor.client_id_trace_enable
APP (client_id, TRUE, FALSE);
Server waits, binds
1

Oracle
S1 S2 S3 S4 S4 S5 S6 S7
Sessions


DB_FILE_MULTI_BLOCK_READ_COUNT
 Auto tuned in 10gR2
 Recommended to leave unset in init.ora, ex, when unset on my PC
 db_file_multiblock_read_count 55
 _db_file_exec_read_count 55 (IO reads)
 _db_file_optimizer_read_count 8 (optimization)
 When running
 Dbms_stats.gather_system_stats(gathering_mode => ‘interval’
interval => 30 )
db_file_multiblock_read_count is ignored
 Alter system reset db_file_multiblock_read_count scope=spfile sid=‘*’;

Troubleshooting Oracle Performance
Christian Antognini

UNDO Retention Auto Tuned
 Oracle10G records the times of the longest-running queries
and the amount of undo generated to automatically tune the
UNDO_RETENTION parameter.
 If Autoextend on then undo retention set slightly longer than
the longest running query
 If autoextend off then depends on free space available
 Bug 5387030 – undo retention miscalculated and UNDO can
grow, fixed 10.2.0.4
 10.2.0.3 or below can set
 alter system set "_smu_debug_mode" = 33554432


SQL Trace Improvement
 dbms_monitor New 10g

dbms_monitor.session_trace_enable(session_id => 127,
serial_num => 29,
waits => TRUE,
binds => FALSE)
10gR2 v$session columns
sql_trace
sql_trace_waits
sql_trace_binds
are set when the procedure
session_trace_enable is used and at least one SQL statement has been executed by the
sessionvtraced

Instead of
alter session set events ‘10046 trace name context forever, level 12';


Q1

An ASH report can be run on data covering what time
periods (by default)
a. any 60 seconds in the past week
b. any hour period in the past day
c. any day in the past week
d. any 60 second period in the past hour

answers
all the above


Q2

AWR ( automatic workload repository ) reports on data
covering
what time periods (by default)
a. any 60 seconds in the past week
b. any hour period in the past day
c. any day in the past week
d. any 60 second period in the past hour
answers
b and c - AWR only takes data every hour for a week
by default

Q3

Connecting to Oracle is a CPU intensive operation. A high
logon rate
may indicate an application design issue that unnecessarily
burns CPU.
What performance table(s) indicates the time spent
connecting to the database ?
b - only
a. v$active_session_history
others
b. v$sys_time_model
a,c,d - don't report
c. v$waitclassmetric connection time or connect
d. v$sysstat CPU usage


Q4

What is the least resource consuming view for getting the
number
of executions of an sql statement

b - new in 10g, less latch usage than the other
a. v$sqllite tables
b. v$sqlstats others
c. v$sql a doesn't exit
d. v$sqlarea c reading uses many of the latches as users
executing sql
d the worst, like v$sql, but also does an
expensive group by Hailey
Copyright 2006 Kyle #.79

Q5

How can you immediately find the top CPU consuming
session in the past 15 seconds

a. v$sessmetric
answer
b. v$active_session_history
a, b
c. v$sesstat
others:
d. v$top_sessions
c - only has cumulative data, need to take
deltas of values to see what is happening
d - doesn't exist


Q6

What script runs 16 different queries against
v$active_session_history to
produce a detailed report over any time interval in the AWR
repository
answer
a. ?/rdbms/admin/spreport.sql
c
b. ?/rdbms/admin/awrrpt.sql
other
c. ?/rdbms/admin/ashrpt.sql
d. ?/rdbms/admin/ashreport.sql ASH
a and b don't use
d doesn't exit


Q7

In 10g, it is recommended to set
db_file_multiblock_read_count to

answer
a. unset
a. Oracle will set it automatically to the optimal
b. 8 value
c. 16 (this won't affect SQL optimization as Oracle
will calculate
d. 32
sql optimization with
e. 128
_db_file_optimizer_read_count )


Q8

Oracle can track different applications using the "services'
identifier.
After the service identifier gets created and started, how
does the
services identifier get set for a connection.
a. call to dbms_services
b. via the tnsnames.ora connection
c. in the init.ora
answer
d. via a middle tier command
b


Q9

The identifier "client_id" allows a DBA to monitor what
special situation:
a. track different applications resource usage on a database
b. track application users in session pools
c. track dedicated sessions
d. is the same as the database "username"
answer
b - set up specifically to track application users
that connect without
a dedicated connection vi a session pool


Oracle 10g Performance: chapter 04 new features

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (6)

Similar to Oracle 10g Performance: chapter 04 new features

Similar to Oracle 10g Performance: chapter 04 new features (20)

More from Kyle Hailey

More from Kyle Hailey (20)

Oracle 10g Performance: chapter 04 new features

Editor's Notes