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action taken on scatterds read [message #317268] Wed, 30 April 2008 05:38 Go to next message
gopu_g
Messages: 54
Registered: March 2008
Location: mumbai
Member
Dear all,
I would like RAISE A Question on Scattered read.

The parameter which we get in v$systen_event views, db file scattered read what action need to take on this parameter and whaty is the couse of this parameter giving values "Total Waits" in v$system _wait view.

Thanks in advance

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Re: action taken on scatterds read [message #317272 is a reply to message #317268] Wed, 30 April 2008 05:47 Go to previous messageGo to next message
Michel Cadot
Messages: 68676
Registered: March 2007
Location: Nanterre, France, http://...
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Are they the main waits?
Are they a real problem? The purpose of a DBMS is to read files, so in the end, when all is well tuned, read wait are the major waits (the opposite is wrong: waits on read does not mean your application is well tuned).

Regards
Michel

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Re: action taken on scatterds read [message #317284 is a reply to message #317272] Wed, 30 April 2008 06:29 Go to previous messageGo to next message
gopu_g
Messages: 54
Registered: March 2008
Location: mumbai
Member
your answer is confusing me ?

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Re: action taken on scatterds read [message #317302 is a reply to message #317284] Wed, 30 April 2008 07:07 Go to previous messageGo to next message
Michel Cadot
Messages: 68676
Registered: March 2007
Location: Nanterre, France, http://...
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How could I answer to this question?

You can read:
- OraFAQ Forum Guide, Performance Tuning section
- How to Identify Performance Problem and Bottleneck
- OraFAQ Oracle SQL Tuning Guide

You can also have a look at Database Performance Tuning Guide, wait events section.

Regards
Michel

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Re: action taken on scatterds read [message #317388 is a reply to message #317302] Wed, 30 April 2008 23:00 Go to previous message
rleishman
Messages: 3728
Registered: October 2005
Location: Melbourne, Australia
Senior Member
Scattered reads are typically the result of a Full Table Scan.
Sequential Reads are typically the result of an Index Scan.

Full Table Scans are not always bad. If they are caused by an ETL or batch job processing large volumes of data, they are probably good. If your statistics were isolated to a period where only OLTP users were on the system, then a high Scattered Reads probably would indicate a problem.
Ross Leishman

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