Statspack for 8.0.5
Does anyone know how to get the statspack scripts for version 8.0.5?
Thanks,
Maher
According to this article, statspack officially exist since 8.1.6, but you can back ported to run on 8.0, some small modification needed.
http://www.dba-oracle.com/art_statspack.htm
Similar Messages
-
Guys,
This is my first time i generated a statspack report as the users were complaining slow response from datbase.
This report is taken when the reports that takes a long time were run.
This is my statspack report.
Message was edited by:
jkestelyHi,
FYI, some tuning guru's are developing an open source free tool to help analyze STATSPACK and AWR reports, which is helpful to beginners:
http://www.statspackanalyzer.com
Also, It may be be a good idea to publish your prouction SQL here (or anywhere else). I've seen DBA's get canned for disclosing proprietary details about their employers database . . . .
Also, a short duration snapshot is not so bad, and I often do on minute snaps when diagnosing a system. Anyhow, here are some observations from SP analyzer:
Hope this helps. . . .
Donald K. Burleson
Author of "Oracle 9i High Performance Tuning with STATSPACK" by Oracle Press
You have enabled system-level parallel query. This can influence the cost-based optimizer to favor full-table scans over index access. Consider using parallel hints instead, or invoking parallelism at the session level.
You may have an application issue causing excessive rollbacks with 47.62% rollbacks per transaction. Due to Oracle´s assumption of a commit, the rollback process is very expensive and should only be used when necessary. You can identify the specific SQL and user session that is executing the rollbacks by querying the v$sesstat view.
Remember that some applications may automatically perform rollback operations (commit-then-rollback or rollback-then-exit) after each commit. If this is the case, speak with your application developers to find out if there is a way to disable this. While these "empty rollbacks" do not incur performance expense, it will case this metric to appear very high.
You have high latch free waits of 1.3 per transaction. The latch free wait occurs when the process is waiting for a latch held by another process. Check the later section for the specific latch waits. Latch free waits are usually due to SQL without bind variables, but buffer chains and redo generation can also cause them.
You have 27,717.0 consistent gets examination per second. "Consistent gets - examination" is different than regular consistent gets. It is used to read undo blocks for consistent read purposes, but also for the first part of an index read and hash cluster I/O.
You have 203,044 table fetch continued row actions during this period. Migrated/chained rows always cause double the I/O for a row fetch and "table fetch continued row" (chained row fetch) happens when we fetch BLOB/CLOB columns (if the avg_row_len > db_block_size), when we have tables with > 255 columns, and when PCTFREE is too small. You may need to reorganize the affected tables with the dbms_redefintion utility and re-set your PCTFREE parameters to prevent future row chaining.
You have 1.1 long table full-table scans per second. This might indicate missing indexes, and you can run plan9i.sql to identify the specific tables and investigate the SQL to see if an index scan might result in faster execution. If your large table full table scans are legitimate, look at optimizing your db_file_multiblock_read_count parameter.
You have high small table full-table scans, at 1.7 per second. Verify that your KEEP pool is sized properly to cache frequently referenced tables and indexes.
You are not using your KEEP pool to cache frequently referenced tables and indexes. This may cause unnecessary I/O. When configured properly, the KEEP pool guarantees full caching of popular tables and indexes. Remember, an average buffer get is often 100 times faster than a disk read.
Any table or index that consumes > 10% of the data buffer, or tables & indexes that have > 50% of their blocks residing in the data buffer should be cached into the KEEP pool. You can fully automate this process using scripts. -
Daily stats required from statspack for graph of month activity
Hi All,
I am trying to get a graph of index io on a daily basis, the trouble is the stats are cumulative since database startup and the database is rarely bounced. So what I actually get is a growing value for each day. I expect there is a simple way to correct my code in sqlplus. ( Otherwise PL/SQL beckons)
Here is my code:
Select to_char(snap_time, 'YYYY-MON-DD') "Day of Mnth",
avg(time_waited_micro)/1000 "index wait duration"
FROM
perfstat.stats$system_event se,
Perfstat.stats$snapshot sn
WHERE se.snap_id = sn.snap_id
and se.event='db file sequential read'
and sn.snap_time between (sysdate - 50) and sysdate
GROUP BY to_char(snap_time, 'YYYY-MON-DD')
order by to_date(to_char(snap_time, 'YYYY-MON-DD'),'YYYY-MON-DD') ;
Thanks in AdvanceHi All,
I am trying to get a graph of index io on a daily basis, the trouble is the stats are cumulative since database startup and the database is rarely bounced. So what I actually get is a growing value for each day. I expect there is a simple way to correct my code in sqlplus. ( Otherwise PL/SQL beckons)
Here is my code:
Select to_char(snap_time, 'YYYY-MON-DD') "Day of Mnth",
avg(time_waited_micro)/1000 "index wait duration"
FROM
perfstat.stats$system_event se,
Perfstat.stats$snapshot sn
WHERE se.snap_id = sn.snap_id
and se.event='db file sequential read'
and sn.snap_time between (sysdate - 50) and sysdate
GROUP BY to_char(snap_time, 'YYYY-MON-DD')
order by to_date(to_char(snap_time, 'YYYY-MON-DD'),'YYYY-MON-DD') ;
Thanks in Advance -
Error in creating perfstat user for statspack
Hi Friends,
DB: 11.2.0.2, SE and 64 bit
OS: RHEL 5.7
My DB is on SE and hence i cannot use the diagonistic pack so when i am trying to use Statspack for the same, i am facing the following error when i am trying to create Perfstat user.
SQL> @?/rdbms/admin/spcreate
Choose the PERFSTAT user's password
Not specifying a password will result in the installation FAILING
Enter value for perfstat_password: perfstat
perfstat
Choose the Default tablespace for the PERFSTAT user
Below is the list of online tablespaces in this database which can
store user data. Specifying the SYSTEM tablespace for the user's
default tablespace will result in the installation FAILING, as
using SYSTEM for performance data is not supported.
Choose the PERFSTAT users's default tablespace. This is the tablespace
in which the STATSPACK tables and indexes will be created.
TABLESPACE_NAME CONTENTS STATSPACK DEFAULT TABLESPACE
INDUS_SML_DATA PERMANENT
INDUS_SML_INDEX PERMANENT
PERFSTAT PERMANENT
SYSAUX PERMANENT *
USERS PERMANENT
Pressing <return> will result in STATSPACK's recommended default
tablespace (identified by *) being used.
Enter value for default_tablespace: PERFSTAT
Using tablespace PERFSTAT as PERFSTAT default tablespace.
Choose the Temporary tablespace for the PERFSTAT user
Below is the list of online tablespaces in this database which can
store temporary data (e.g. for sort workareas). Specifying the SYSTEM
tablespace for the user's temporary tablespace will result in the
installation FAILING, as using SYSTEM for workareas is not supported.
Choose the PERFSTAT user's Temporary tablespace.
TABLESPACE_NAME CONTENTS DB DEFAULT TEMP TABLESPACE
TEMP TEMPORARY *
Pressing <return> will result in the database's default Temporary
tablespace (identified by *) being used.
Enter value for temporary_tablespace: TEMP
Using tablespace TEMP as PERFSTAT temporary tablespace.
... Creating PERFSTAT user
... Installing required packages
... Creating views
... Granting privileges
NOTE:
SPCUSR complete. Please check spcusr.lis for any errors.
SQL>
SQL> --
SQL> -- Build the tables and synonyms
SQL> connect perfstat/&&perfstat_password
Connected.
SQL> @@spctab
SQL> Rem
SQL> Rem $Header: rdbms/admin/spctab.sql /st_rdbms_11.2.0/1 2010/08/13 10:06:01 kchou Exp $
SQL> Rem
SQL> Rem spctab.sql
SQL> Rem
SQL> Rem Copyright (c) 1999, 2010, Oracle and/or its affiliates.
SQL> Rem All rights reserved.
SQL> Rem
SQL> Rem NAME
SQL> Rem spctab.sql
SQL> Rem
SQL> Rem DESCRIPTION
SQL> Rem SQL*PLUS command file to create tables to hold
SQL> Rem start and end "snapshot" statistical information
SQL> Rem
SQL> Rem NOTES
SQL> Rem Should be run as STATSPACK user, PERFSTAT
SQL> Rem
SQL> Rem MODIFIED (MM/DD/YY)
SQL> Rem kchou 08/11/10 - Bug#9800868 - Add Missing Idle Events for
SQL> Rem 11.2.0.2for Statspack & Standby Statspack
SQL> Rem kchou 08/11/10 - Bug#9800868 - Add missing idle events to 11.2.0.2
SQL> Rem cgervasi 05/13/09 - add idle event: cell worker idle
SQL> Rem cgervasi 04/02/09 - bug8395154: missing idle events
SQL> Rem rhlee 02/22/08 -
Rem cdgreen 03/14/07 - 11 F2SQL> Rem shsong 06/14/07 - Add idle events
SQL> Rem cdgreen 02/28/07 - 5908354
SQL> Rem cdgreen 04/26/06 - 11 F1
SQL> Rem cdgreen 06/26/06 - Increase column length
SQL> Rem cdgreen 05/10/06 - 5215982
SQL> Rem cdgreen 05/24/05 - 4246955
SQL> Rem cdgreen 04/18/05 - 4228432
SQL> Rem cdgreen 03/08/05 - 10gR2 misc
SQL> Rem vbarrier 02/18/05 - 4081984
SQL> Rem cdgreen 10/29/04 - 10gR2_sqlstats
SQL> Rem cdgreen 07/16/04 - 10gR2
SQL> Rem cdialeri 03/25/04 - 3516921
SQL> Rem vbarrier 02/12/04 - 3412853
SQL> Rem cdialeri 12/04/03 - 3290482
SQL> Rem cdialeri 11/05/03 - 3202706
SQL> Rem cdialeri 10/14/03 - 10g - streams - rvenkate
SQL> Rem cdialeri 08/05/03 - 10g F3
SQL> Rem cdialeri 02/27/03 - 10g F2: baseline, purge
SQL> Rem vbarrier 02/25/03 - 10g RAC
SQL> Rem cdialeri 11/15/02 - 10g F1
SQL> Rem cdialeri 09/27/02 - sleep4
SQL> Rem vbarrier 03/20/02 - 2143634
SQL> Rem vbarrier 03/05/02 - Segment Statistics
SQL> Rem cdialeri 02/07/02 - 2218573
SQL> Rem cdialeri 01/30/02 - 2184717
SQL> Rem cdialeri 01/11/02 - 9.2 - features 2
SQL> Rem cdialeri 11/30/01 - 9.2 - features 1
SQL> Rem cdialeri 04/22/01 - Undostat changes
SQL> Rem cdialeri 03/02/01 - 9.0
SQL> Rem cdialeri 09/12/00 - sp_1404195
SQL> Rem cdialeri 04/07/00 - 1261813
SQL> Rem cdialeri 03/20/00 - Support for purge
SQL> Rem cdialeri 02/16/00 - 1191805
SQL> Rem cdialeri 01/26/00 - 1169401
SQL> Rem cdialeri 11/01/99 - Enhance, 1059172
SQL> Rem cmlim 07/17/97 - Added STATS$SQLAREA to store top sql stmts
SQL> Rem gwood 10/16/95 - Version to run as sys without using many view
SQL> Rem cellis.uk 11/15/89 - Created
SQL> Rem
SQL>
SQL> set showmode off echo off;
If this script is automatically called from spcreate (which is
the supported method), all STATSPACK segments will be created in
the PERFSTAT user's default tablespace.
Using PERFSTAT tablespace to store Statspack objects
... Creating STATS$SNAPSHOT_ID Sequence
Sequence created.
create public synonym STATS$SNAPSHOT_ID for STATS$SNAPSHOT_ID
ERROR at line 1:
ORA-00955: name is already used by an existing object
Disconnected from Oracle Database 11g Release 11.2.0.2.0 - 64bit Production
Kindly suggest on the same..
BR@?/rdbms/admin/spdrop
drop public synonym STATS$SNAPSHOT_ID;
try again -
HOW TO REVIEW STATSPACK REPORT
dear all
i have sucessfully done with statspack
i know how to analyse with
1.Instance Efficiency Percentages (Target 100%)
2.Top 5 Timed Events
3. Buffer Gets Executions Gets per Exec %Total Time
4.tablespace
but i want to explore more on statspack pls let me know how to analyse more on report
please let me know where i can find it
regardsSagar,
Jonathan Lewis has discussed about what to read in statspack report and what not as serious of articles on his blog.
http://jonathanlewis.wordpress.com/tag/oracle/statspack/
For me, I felt, they are worth to read and understand.
Jaffar -
STATSPACK Performance Question / Discrepancy
I'm trying to troubleshoot a performance issue and I'm having trouble interpreting the STATSPACK report. It seems like the STATSPACK report is missing information that I expect to be there. I'll explain below.
Header
STATSPACK report for
Database DB Id Instance Inst Num Startup Time Release RAC
~~~~~~~~ ----------- ------------ -------- --------------- ----------- ---
2636235846 testdb 1 30-Jan-11 16:10 11.2.0.2.0 NO
Host Name Platform CPUs Cores Sockets Memory (G)
~~~~ ---------------- ---------------------- ----- ----- ------- ------------
TEST Microsoft Windows IA ( 4 2 0 3.4
Snapshot Snap Id Snap Time Sessions Curs/Sess Comment
~~~~~~~~ ---------- ------------------ -------- --------- ------------------
Begin Snap: 3427 01-Feb-11 06:40:00 65 4.4
End Snap: 3428 01-Feb-11 07:00:00 66 4.1
Elapsed: 20.00 (mins) Av Act Sess: 7.3
DB time: 146.39 (mins) DB CPU: 8.27 (mins)
Cache Sizes Begin End
~~~~~~~~~~~ ---------- ----------
Buffer Cache: 192M 176M Std Block Size: 8K
Shared Pool: 396M 412M Log Buffer: 10,848K
Load Profile Per Second Per Transaction Per Exec Per Call
~~~~~~~~~~~~ ------------------ ----------------- ----------- -----------
DB time(s): 7.3 2.0 0.06 0.04
DB CPU(s): 0.4 0.1 0.00 0.00
Redo size: 6,366.0 1,722.1
Logical reads: 1,114.6 301.5
Block changes: 35.8 9.7
Physical reads: 44.9 12.1
Physical writes: 1.5 0.4
User calls: 192.2 52.0
Parses: 101.5 27.5
Hard parses: 3.6 1.0
W/A MB processed: 0.1 0.0
Logons: 0.1 0.0
Executes: 115.1 31.1
Rollbacks: 0.0 0.0
Transactions: 3.7As you can see a significant amount of time was spent in database calls (DB Time) with relatively little time on CPU (DB CPU). Initially that made me think there were some significant wait events.
Top 5 Timed Events Avg %Total
~~~~~~~~~~~~~~~~~~ wait Call
Event Waits Time (s) (ms) Time
log file sequential read 48,166 681 14 7.9
CPU time 484 5.6
db file sequential read 35,357 205 6 2.4
control file sequential read 50,747 23 0 .3
Disk file operations I/O 16,518 18 1 .2
-------------------------------------------------------------However, looking at the Top 5 Timed Events I don't see anything out of the ordinary given my normal operations. the log file sequential read may be a little slow but it doesn't make up a significant portion of the execution time.
Based on an Excel/VB spreadsheet I wrote, which converts STATSPACK data to graphical form, I suspected that there was a wait event not listed here. So I decided to query the data directly. Here is the query and result.
SQL> SELECT wait_class
2 , event
3 , delta/POWER(10,6) AS delta_sec
4 FROM
5 (
6 SELECT syev.snap_id
7 , evna.wait_class
8 , syev.event
9 , syev.time_waited_micro
10 , syev.time_waited_micro - LAG(syev.time_waited_micro) OVER (PARTITION BY syev.event ORDER BY syev.snap_id) AS delta
11 FROM perfstat.stats$system_event syev
12 JOIN v$event_name evna ON evna.name = syev.event
13 WHERE syev.snap_id IN (3427,3428)
14 )
15 WHERE delta > 0
16 ORDER BY delta DESC
17 ;
?WAIT_CLASS EVENT DELTA_SEC
Idle SQL*Net message from client 21169.742
Idle rdbms ipc message 19708.390
Application enq: TM - contention 7199.819
Idle Space Manager: slave idle wait 3001.719
Idle DIAG idle wait 2382.943
Idle jobq slave wait 1258.829
Idle smon timer 1220.902
Idle Streams AQ: qmn coordinator idle wait 1204.648
Idle Streams AQ: qmn slave idle wait 1204.637
Idle pmon timer 1197.898
Idle Streams AQ: waiting for messages in the queue 1197.484
Idle Streams AQ: waiting for time management or cleanup tasks 791.803
System I/O log file sequential read 681.444
User I/O db file sequential read 204.721
System I/O control file sequential read 23.168
User I/O Disk file operations I/O 17.737
User I/O db file parallel read 14.536
System I/O log file parallel write 7.618
Commit log file sync 7.150
User I/O db file scattered read 3.488
Idle SGA: MMAN sleep for component shrink 2.461
User I/O direct path read 1.621
Other process diagnostic dump 1.418
... snip ...So based on the above it looks like there was a significant amount of time spent in enq: TM - contention
Question 1
Why does this wait event not show up in the Top 5 Timed Events section? Note that this wait event is also not listed in any of the other wait events sections either.
Moving on, I decided to look at the Time Model Statistics
Time Model System Stats DB/Inst: testdb /testdb Snaps: 3427-3428
-> Ordered by % of DB time desc, Statistic name
Statistic Time (s) % DB time
sql execute elapsed time 8,731.0 99.4
PL/SQL execution elapsed time 1,201.1 13.7
DB CPU 496.3 5.7
parse time elapsed 26.4 .3
hard parse elapsed time 21.1 .2
PL/SQL compilation elapsed time 2.8 .0
connection management call elapsed 0.6 .0
hard parse (bind mismatch) elapsed 0.5 .0
hard parse (sharing criteria) elaps 0.5 .0
failed parse elapsed time 0.0 .0
repeated bind elapsed time 0.0 .0
sequence load elapsed time 0.0 .0
DB time 8,783.2
background elapsed time 87.1
background cpu time 2.4Great, so it looks like I spent >99% of DB Time in SQL calls. I decided to scroll to the SQL ordered by Elapsed time section. The header information surprised me.
SQL ordered by Elapsed time for DB: testdb Instance: testdb Snaps: 3427 -3
-> Total DB Time (s): 8,783
-> Captured SQL accounts for 4.1% of Total DB Time
-> SQL reported below exceeded 1.0% of Total DB TimeIf I'm spending > 99% of my time in SQL, I would have expected the captured % to be higher.
Question 2
Am I correct in assuming that a long running SQL that started before the first snap and is still running at the end of the second snap would not display in this section?
Question 3
Would that answer my wait event question above? Ala, are wait events not reported until the action that is waiting (execution of a SQL statement for example) is complete?
So I looked a few snaps past what I have posted here. I still haven't determined why the enq: TM - contention wait is not displayed anywhere in the STATSPACK reports. I did end up finding an interesting PL/SQL block that may have been causing the issues. Here is the SQL ordered by Elapsed time for a snapshot that was taken an hour after the one I posted.
SQL ordered by Elapsed time for DB: testdb Instance: testdb Snaps: 3431 -3
-> Total DB Time (s): 1,088
-> Captured SQL accounts for ######% of Total DB Time
-> SQL reported below exceeded 1.0% of Total DB Time
Elapsed Elap per CPU Old
Time (s) Executions Exec (s) %Total Time (s) Physical Reads Hash Value
26492.65 29 913.54 ###### 1539.34 480 1013630726
Module: OEM.CacheModeWaitPool
BEGIN EMDW_LOG.set_context(MGMT_JOB_ENGINE.MODULE_NAME, :1); BEG
IN MGMT_JOB_ENGINE.process_wait_step(:2);END; EMDW_LOG.set_conte
xt; END;I'm still not sure if this is the problem child or not.
I just wanted to post this to get your thoughts on how I correctly/incorrectly attacked this problem and to see if you can fill in any gaps in my understanding.
Thanks!Centinul wrote:
I'm still not sure if this is the problem child or not.
I just wanted to post this to get your thoughts on how I correctly/incorrectly attacked this problem and to see if you can fill in any gaps in my understanding.
I think you've attacked the problem well.
It has prompted me to take a little look at what's going on, running 11.1.0.6 in my case, and something IS broken.
The key predicate in statspack for reporting top 5 is:
and e.total_waits > nvl(b.total_waits,0)In other words, an event gets reported if total_waits increased across the period.
So I've been taking snapshots of v$system_event and looking at 10046 trace files at level 8. The basic test was as simple as:
<ul>
Session 1: lock table t1 in exclusive mode
Session 2: lock table t1 in exclusive mode
</ul>
About three seconds after session 2 started to wait, v$system_event incremented total_waits (for the "enq: TM - contention" event). When I committed in session 1 the total_waits figure did not change.
Now do this after waiting across a snapshot:
We start to wait, after three seconds we record a wait, a few minutes later perfstat takes a snapshot.
30 minutes later "session 1" commits and our wait ends, but we do not increment total_waits, but we record 30+ minutes wait time.
30 minutes later perfstat takes another snapshot
The total_waits has not changed between the start and end snapshot even though we have added 30 minutes to the "enq: TM - contention" in the interim.
The statspack report loses our 30 minutes from the Top N.
It's a bug - raise an SR.
Edit: The AWR will have the same problem, of course.
Regards
Jonathan Lewis
Edited by: Jonathan Lewis on Feb 1, 2011 7:07 PM -
Urgt:How to identify TOP 5 SQL using more CPU time without using statspack
How to identify the TOP 5 SQL queries which are consuming more CPU time during the timespan of 24 hours for entire database. There are N number of users who have issued sql queries, out of which few users have disconnected and few user are still connected to the database(I need to consider all sessions). My database version is 9.0.1. I don't want to use statspack. Is there any way to identify TOP 5 SQL consuming more CPU time without affecting the performance of the database. Can any one help me on this? Its urgent!!. I don't want to use statspack becasue it degrades the performance and i cannot afford to run it for 24 hours.
You don't run statspack for 24 hours, that would infact be pointless...
Run statspack for say a 10 or 15 minute window during a particular "busy" period on your database. If you run it for longer then all the useful data will have been "averaged out". You want a snapshot in time, not an average over the day. -
Hi,
Looking at the Server Statistics in Toad, I see that I have "PCTFREE too low for a table". How do I know which table?
Thanks,
JohannaDon't know much about "Toad Statistics" but which version of database are you on?? and are you using LMT?? Run statspack for more accurate statistics and it will be helpfull to identify the root cause. Are you experiencing any performance problems??
Daljit Singh -
Which tool is used for Oracle 11g performance tuning?
Hi all
I used statspack for 9i's performance tuning.
But with 11g R2 now I want to know which way are you using to do performance tuning?
Statspack? OSW? RDA? ADDM? Or other ways?
Thank you.schavali wrote:
I would start with Automatic Workload Repository (AWR) reports to identify the bottleneck
MOS Doc 390374.1 - Oracle Performance Diagnostic Guide (OPDG)
MOS Doc 748642.1 - What is AWR( Automatic workload repository ) and How to generate the AWR report?
HTH
SriniThanks for your answer.
To read the MOS documents I need a Oracle Customer ID , is that right ?
(Where to get that ID ? Our company bought Oracle 10g without any Customer IDs in it )
Best Wishes. -
I have created statspack for snap(0)
while seeing report
it ask begin and end_snap ids..... here what i have to specify
plz anyone help me...hi,
first connect to perfstat user with password
2) sql> exec statspack.snap;
pl/sql procedure successfully completed.
=> snap shot 1 or any other number will be created.
then do some changes in the table like insert,update, delete, etc
again use after sometime
sql> exec statspack.snap
pl/sql procedure successfully completed.
now run the spreport.sql script
it will show the snap shot number existing and ask for begin and end snapshot numbers
you give the numbers generated.
then give the path where the text file to be stored. You can statspack report. -
Hey Gang,
I need to track the User and table activity. My goal is to find out what tables are static and which are not. Which user classes should be changed and how access should be assigned. This will also allow me to tune the database accordingly.Instead of trying to track individual user and table usage look at statspack for issues related to tuning the database. Generally unless you really did a poor job laying out and configuring your db to begin with the db does not need much tuning. The SQL is another story.
Look into the following
ver 9+ monitor command in DBA Admin, SQL manual
ver all Audit command in DBA Admin manual, SQL manual
ver 8.1+ Db event triggers (logon) DBA Concepts and Admin
HTH -- Mark D Powell -- -
I have something wrong with my production Instance... The Database server CPU goes up to 70%. I executed some performance queries and I get the following ..
BUFFER_GETS SQL_TEXT
74434 SELECT count(*) FROM ...............
74166 SELECT PAYROLL,.............
71063 SELECT ........
214 rows selected.
I get 214 rows whose buffer_gets > 70000.... What steps we need to perform to tun the database?What you just did is the first step. You identified the top SQLs running on your system. You can use Oracle Top SQL, Precise, Quest Central or any other GUI tools to identify the top SQLs easily. Or use the built in STATSPACK for that.
From there, you want to make sure that all SQLs are part of your application code, and are not developer queries used for reports (prepare a different database for that purpose). If the count(*) query is a valid statement, you should think if a materialized view is something you can work with instead of counting the data in each statement.
In short:
- Find the top ten queries in you DB.
- Identify the execution plans for each statement. Resolve full table scans and bad joins. Make sure the data is accessed in an optimized way.
- Look for a way to use mviews to summarize data in advance.
Good luck,
Idan Magal. -
Thread 1 cannot allocate new log, sequence in Alert log
Could someone help, I am getting the below message in my alert log
System: AIX6.1 - Oracle 11r2
GROUP# THREAD# MEMBER ARCHIVED STATUS MB
1 1 +DATA01/mydb/redolog_group1_member1 NO INACTIVE 1536
1 1 +DATA01/mydb/redolog_group1_member2 NO INACTIVE 1536
2 1 +DATA01/mydb/redolog_group2_member2 NO CURRENT 1536
2 1 +DATA01/mydb/redolog_group2_member1 NO CURRENT 1536
3 1 +DATA01/mydb/redolog_group3_member2 NO INACTIVE 1536
3 1 +DATA01/mydb/redolog_group3_member1 NO INACTIVE 1536
Tue Jul 10 18:37:48 2012
Thread 1 advanced to log sequence 28831 (LGWR switch)
Current log# 1 seq# 28831 mem# 0: +DATA01/mydb/redolog_group1_member1
Current log# 1 seq# 28831 mem# 1: +DATA01/mydb/redolog_group1_member2
Tue Jul 10 19:12:01 2012
Thread 1 advanced to log sequence 28832 (LGWR switch)
Current log# 2 seq# 28832 mem# 0: +DATA01/mydb/redolog_group2_member1
Current log# 2 seq# 28832 mem# 1: +DATA01/mydb/redolog_group2_member2
Tue Jul 10 19:39:00 2012
Thread 1 cannot allocate new log, sequence 28833
Private strand flush not complete
Tue Jul 10 19:39:18 2012
Current log# 2 seq# 28832 mem# 0: +DATA01/mydb/redolog_group2_member1
Current log# 2 seq# 28832 mem# 1: +DATA01/mydb/redolog_group2_member2
Tue Jul 10 19:41:21 2012
Thread 1 advanced to log sequence 28833 (LGWR switch)
Current log# 3 seq# 28833 mem# 0: +DATA01/mydb/redolog_group3_member1
Current log# 3 seq# 28833 mem# 1: +DATA01/mydb/redolog_group3_member2
Tue Jul 10 20:15:28 2012
Thread 1 cannot allocate new log, sequence 28834
Private strand flush not complete
Current log# 3 seq# 28833 mem# 0: +DATA01/mydb/redolog_group3_member1
Current log# 3 seq# 28833 mem# 1: +DATA01/mydb/redolog_group3_member2
Tue Jul 10 20:16:21 2012Could an increase on the redo log file sizes solve this problem? Unfortunately I do not have a test platform, where I could have tested this.mseberg wrote:
It just a warning. I would read these two notes:
I suspect the OP is more worried about the apparent two minute gap between the "cannot switch" and the "advanced" at 19:39:18 and 19:41:12 respectively. Did the switch really have to wait for that two minutes, or is this a spurious threat caused by an anomaly in the writing of the alert log.
As a cross check, I would examine v$event_histogram (or an AWR/Statspack for the interval) for time spent in the event "log file switch (private strand flush incomplete)". In prinicple I wouldn't expect to see waits longer than a few (less than 10) milliseconds; if the histogram shows long waits consistent with the alert log reports than I'd contact Oracle because something odd is happening.
(Footnote - it's possible that the event times out after a limited interval, log file sync used to time out after 1 second and has recently changed to something shorter and adjustable, so 2 seconds may (for example) appear as 20 x 0.1 seconds.)
Regards
Jonathan Lewis -
JDBC, SQL*Net wait interface, performance degradation on 10g vs. 9i
Hi All,
I came across performance issue that I think results from mis-configuration of something between Oracle and JDBC. The logic of my system executes 12 threads in java. Each thread performs simple 'select a,b,c...f from table_xyz' on different tables. (so I have 12 different tables with cardinality from 3 to 48 millions and one working thread per table).
In each thread I'm creating result set that is explicitly marked as forward_only, transaction is set read only, fetch size is set to 100000 records. Java logic processes records in standard while(rs.next()) {...} loop.
I'm experiencing performance degradation between execution on Oracle 9i and Oracle 10g of the same java code, on the same machine, on the same data. The difference is enormous, 9i execution takes 26 hours while 10g execution takes 39 hours.
I have collected statspack for 9i and awr report for 10g. Below I've enclosed top wait events for 9i and 10g
===== 9i ===================
Avg
Total Wait wait Waits
Event Waits Timeouts Time (s) (ms) /txn
db file sequential read 22,939,988 0 6,240 0 0.7
control file parallel write 6,152 0 296 48 0.0
SQL*Net more data to client 2,877,154 0 280 0 0.1
db file scattered read 26,842 0 91 3 0.0
log file parallel write 3,528 0 83 23 0.0
latch free 94,845 0 50 1 0.0
process startup 93 0 5 50 0.0
log file sync 34 0 2 46 0.0
log file switch completion 2 0 0 215 0.0
db file single write 9 0 0 33 0.0
control file sequential read 4,912 0 0 0 0.0
wait list latch free 15 0 0 12 0.0
LGWR wait for redo copy 84 0 0 1 0.0
log file single write 2 0 0 18 0.0
async disk IO 263 0 0 0 0.0
direct path read 2,058 0 0 0 0.0
slave TJ process wait 1 1 0 12 0.0
===== 10g ==================
Avg
%Time Total Wait wait Waits
Event Waits -outs Time (s) (ms) /txn
db file scattered read 268,314 .0 2,776 10 0.0
SQL*Net message to client 278,082,276 .0 813 0 7.1
io done 20,715 .0 457 22 0.0
control file parallel write 10,971 .0 336 31 0.0
db file parallel write 15,904 .0 294 18 0.0
db file sequential read 66,266 .0 257 4 0.0
log file parallel write 3,510 .0 145 41 0.0
SQL*Net more data to client 2,221,521 .0 102 0 0.1
SGA: allocation forcing comp 2,489 99.9 27 11 0.0
log file sync 564 .0 23 41 0.0
os thread startup 176 4.0 19 106 0.0
latch: shared pool 372 .0 11 29 0.0
latch: library cache 537 .0 5 10 0.0
rdbms ipc reply 57 .0 3 49 0.0
log file switch completion 5 40.0 3 552 0.0
latch free 4,141 .0 2 0 0.0
I put full blame for the slowdown on SQL*Net message to client wait event. All I could find about this event is that it is a network related problem. I assume it would be true if database and client were on different machines.. However in my case they are on them very same machine.
I'd be very very grateful if someone could point me in the right direction, i.e. give a hint what statistics should I analyze further? what might cause this event to appear? why probable cause (that is said be outside db) affects only 10g instance?
Thanks in advance,
Rafi.Hi Steven,
Thanks for the input. It's a fact that I did not gather statistics on my tables. My understanding is that statistics are useful for queries more complex than simple select * from table_xxx. In my case tables don't have indexes. There's no filtering condition as well. Full table scan is what I actually want as all software logic is inside the java code.
Explain plans are as follows:
======= 10g ================================
PLAN_TABLE_OUTPUT
Plan hash value: 1141003974
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | 1 | 259 | 2 (0)| 00:00:01 |
| 1 | TABLE ACCESS FULL| xxx | 1 | 259 | 2 (0)| 00:00:01 |
In sqlplus I get:
SQL> set autotrace traceonly explain statistics;
SQL> select * from xxx;
36184384 rows selected.
Elapsed: 00:38:44.35
Execution Plan
Plan hash value: 1141003974
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | 1 | 259 | 2 (0)| 00:00:01 |
| 1 | TABLE ACCESS FULL| xxx | 1 | 259 | 2 (0)| 00:00:01 |
Statistics
1 recursive calls
0 db block gets
3339240 consistent gets
981517 physical reads
116 redo size
26535700 bytes received via SQL*Net from client
2412294 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
36184384 rows processed
======= 9i =================================
PLAN_TABLE_OUTPUT
| Id | Operation | Name | Rows | Bytes | Cost |
| 0 | SELECT STATEMENT | | | | |
| 1 | TABLE ACCESS FULL | xxx | | | |
Note: rule based optimization
In sqlplus I get:
SQL> set autotrace traceonly explain statistics;
SQL> select * from xxx;
36184384 rows selected.
Elapsed: 00:17:43.06
Execution Plan
0 SELECT STATEMENT Optimizer=CHOOSE
1 0 TABLE ACCESS (FULL) OF 'xxx'
Statistics
0 recursive calls
1 db block gets
3306118 consistent gets
957515 physical reads
100 redo size
23659424 bytes sent via SQL*Net to client
26535867 bytes received via SQL*Net from client
2412294 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
36184384 rows processed
Thanks for pointing me difference in table scans. I infer that 9i is doing single-block full table scan (db file sequential read) while 10g is using multi-block full table scan (db file scattered read).
I now have theory that 9i is faster because sequential reads use continuous buffer space while scattered reads use discontinuous buffer space. Since I'm accessing data 'row by row' in jdbc 10g might have an overhead in providing data from discontinuous buffer space. This overhead shows itself as SQL*Net message to client wait. Is that making any sense?
Is there any way I could force 10g (i.e. with hint) to use sequential reads instead of scattered reads for full table scan?
I'll experiment with FTS tuning in 10g by enabling automatic multi-block reads tuning (i.e. db_file_multiblock_read_count=0 instead of 32 as it is now). I'll also check if response time improves after statistics are gathered.
Please advice if you have any other ideas.
Thanks & regards,
Rafi. -
Which SQL statement is he running?
I have some oracle processes which are consuming a big fraction of the CPU resources and the load is so big that no users can connect (except with connect / as sysdba). Knowing their PID (from the UNIX top command), and connecting internally on Oracle, is there a way to know which statements are currently being performed by these users?
NB: Database in question is Oracle 10g.Just because users cannot connect does not mean the problem is a "load" problem.
What does v$session_wait show that connected sessions are waiting on? Are any sessions lock waited?
If there are lockwaited sessions are any of the Oracle rdbms background sessions involved in the lock problem?
In situations where people cannot connect or take five minutes to do so the problem usually comes down to improper configuration of the database, poor design of the most heavily hit section of an application, or your are especially lucky and have managed to hit a bug.
In the absence of a locking problem or every session waiting on the same resouce then a statspack for a short duration is worth a shot (providing it will run).
HTH -- Mark D Powell --
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