Re: question on dbazine article
- From: "Tanel P?der" <tanel.poder.003@xxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 26 Feb 2004 22:07:35 +0200
In 10g alter system works as well.
Tanel.
----- Original Message -----
From: Powell, Mark D
To: 'oracle-l@xxxxxxxxxxxxx'
Sent: Thursday, February 26, 2004 5:36 PM
Subject: RE: question on dbazine article
Perhaps he meant to change the parameter at the session level. Also your
Oracle version may come into play here also.
1* alter system set optimizer_index_caching = 85 scope = spfile
@UT1 SQL>> /
System altered.
@UT1 SQL>> alter session set optimizer_index_caching = 85;
Session altered.
Test ran on 9.2.0.4 AIX 4.3.3
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of zhu chao
Sent: Thursday, February 26, 2004 8:16 AM
To: oracle-l@xxxxxxxxxxxxx
Cc: Yong Huang
Subject: question on dbazine article
http://www.dbazine.com/burleson20.shtml
I often visit dbazine and read articlles there, on this issue, I have some
questions:
question to that article:
1. he said:
alter system set optimizer_index_cost_adj=20;
alter system set optimizer_index_caching=65.
but in fact, these parameters cannot be modified online. How did he do
that?
2.Implement cursor_sharing=force
According to wait event based tuning, tuning something that is not the
bottleneck does not helps much. In his case, euqueue wait and full table scan
caused most of the problem. Would change cursor_sharing be the solution of his
problem?
3. question about add freelists;
He has 450 users inserting records, even if one person can insert a
record every 3 seconds, it is only possible that there is 150 new records per
second. Can't oracle process 150 record insert per second even if only 1
freelists? I did a small test with 300 concurrent session doing insert into a
table, each insert a table after 3 second sleep. and this is the statspack
report:( i removed the plsql locker timer event from statspack via modifying
stats$idle_event).
Top 5 Wait Events
~~~~~~~~~~~~~~~~~ Wait %
Total
Event Waits Time (cs) Wt
Time
-------------------------------------------- ------------ ------------
-------
log file parallel write 25,955 2,345
90.72
control file parallel write 146 109
4.22
db file parallel write 168 55
2.13
buffer busy waits 30,761 34
1.32 --only a few percent of that.
log file switch completion 4 22
.85
Regards
Zhu chao.
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