RE: [QUAR] Re: latch wait - cache buffer chain
- From: "Bobak, Mark" <Mark.Bobak@xxxxxxxxxxxxxxx>
- To: <genegurevich@xxxxxxxxxxxxxxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 24 Oct 2006 19:15:05 -0400
What version of Oracle? In 10g, there are SQL Profiles. In previous
versions, stored outlines...one of them may do the trick.
--
Mark J. Bobak
Senior Oracle Architect
ProQuest Information & Learning
There is nothing so useless as doing efficiently that which shouldn't be
done at all. -Peter F. Drucker, 1909-2005
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of
genegurevich@xxxxxxxxxxxxxxxxxxxxx
Sent: Tuesday, October 24, 2006 6:21 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: [QUAR] Re: latch wait - cache buffer chain
Importance: Low
Well, I have executed the same SQL without the index (supressed it by
adding a +0 to a where clause) and it completed in 32 minutes. Still
nothing to write home about , but better than it was. However the
report is created by a reporting tool and I can't manipulate the SQL. Is
there a way to rebuild that index or change some parameters based on my
findings so that it does not slow down my SQL?
Thanks for any input
thank you
Gene Gurevich
Oracle Engineering
224-405-4079
genegurevich@disc
overfinancial.com
Sent by:
To
oracle-l-bounce@f oracle-l@xxxxxxxxxxxxx
reelists.org
cc
frits.hoogland@xxxxxxxxx, "goran
bogdanovic" <goran00@xxxxxxxxx>
10/24/2006 05:01
Subject
PM Re: latch wait - cache buffer
chain
Please respond to
genegurevich@disc
overfinancial.com
Thank you. Goran and Fritz.
I have now identified an index with a number of "hot" extents. I
noticed that all the extents in the output of my SQL have the same child
latch #. I am not sure whether this is OK. I am now trying to rerun my
SQL without the index that was on the hot list to see if that helps.
This index is parallelized and the SQL is executed with 8 readers and 8
writers. Should I change the value of freelist of my index based on
that?
thank you
Gene Gurevich
"goran
bogdanovic"
<goran00@xxxxxxxx
To
m>
genegurevich@xxxxxxxxxxxxxxxxxxxxx
cc
10/24/2006 03:33 frits.hoogland@xxxxxxxxx,
PM oracle-l@xxxxxxxxxxxxx
Subject
Re: latch wait - cache buffer
chain
take the p1raw from the v$session_wait for waiting session and this is
your hladdr in the query you are looking for.
On 10/24/06, Frits Hoogland < frits.hoogland@xxxxxxxxx> wrote:
You should find the hottest child latch yourself, and swap the value
of
ADDR on line 12 with the value of hladdr of the child latch.
if you execute this query, no rows should come up, because the chance
of
having an hladdr = 'ADDR' in x$bh is fairly low.
cheers!
frits
On 10/24/06, genegurevich@xxxxxxxxxxxxxxxxxxxxx <
genegurevich@xxxxxxxxxxxxxxxxxxxxx> wrote:
He everybody:
I am trying to tune a report which has been running for some time and
has
been timing out since last week.
When I execute that report I see a large number of "latch free" wait
events
with p2 parameter equal to 98.
Based on v$latch that is a cache buffer chain latch. One of the
reasons
for this event can be a hot block.
I have found the following query on the metalink to locate a hot
block:
1 select /*+ RULE */
2 e.owner ||'.'|| e.segment_name segment_name,
3 e.extent_id extent#,
4 x.dbablk - e.block_id + 1 block#,
5 x.tch,
6 l.child#
7 from
8 sys.v$latch_children l,
9 sys.x$bh x,
10 sys.dba_extents e
11 where
12 x.hladdr = 'ADDR' and
13 e.file_id = x.file# and
14 x.hladdr = l.addr and
15 x.dbablk between e.block_id and e.block_id + e.blocks -1
16* order by x.tch desc
but it did not return anything. Is there anything else I need to look
at
related to this latch?
Thanks for any insight
thank you
Gene Gurevich
--
//www.freelists.org/webpage/oracle-l
--
//www.freelists.org/webpage/oracle-l
--
//www.freelists.org/webpage/oracle-l
--
//www.freelists.org/webpage/oracle-l
Other related posts:
