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Performance issue with Oracle Cluster [message #324798]

Wed, 04 June 2008 01:47

sarwagya
Messages: 87
Registered: February 2008
Location: Republic of Nepal

Member

Dear All,

I am trying to use clusters to upgrade the performance of my queries.
I have few questions regarding clusters:

#How the performance varies with the increase in the number of associated rows?
#Can the clustered tables be partitioned further?
#what are the main disadvantages of using clustered tables?

Could you please help me find the answers to these questions.

Thanks in advance.

Sarwagya.

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Re: Performance issue with Oracle Cluster [message #324803 is a reply to message #324798]

Wed, 04 June 2008 02:32

Michel Cadot
Messages: 68664
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
Account Moderator

Database Performance Tuning Guide
Chapter 15 Using Indexes and Clusters

Regards
Michel

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Re: Performance issue with Oracle Cluster [message #324846 is a reply to message #324803]

Wed, 04 June 2008 05:47

sarwagya
Messages: 87
Registered: February 2008
Location: Republic of Nepal

Member

Thanks Michel.

I went through the doc.
But got confused on the line:

Store a detail table alone in a cluster if you often select many detail records of the same master. This measure improves the performance of queries that select detail records of the same master, but does not decrease the performance of a full table scan on the master table. An alternative is to use an index organized table.

My question is:
How are the rows organized in a cluster if there is only one table in it?

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Re: Performance issue with Oracle Cluster [message #324849 is a reply to message #324846]

Wed, 04 June 2008 06:03

Michel Cadot
Messages: 68664
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
Account Moderator

Quote:

How are the rows organized in a cluster if there is only one table in it?

In the order of the cluster column.

Regards
Michel

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Re: Performance issue with Oracle Cluster [message #324857 is a reply to message #324849]

Wed, 04 June 2008 06:26

sarwagya
Messages: 87
Registered: February 2008
Location: Republic of Nepal

Member

Then it seems good.

Is there any drawback of creating a single table cluster?

Also, I didn't find anything regarding my previous question:

Can a clustered table be partitioned later on if its size increases significantly?

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Re: Performance issue with Oracle Cluster [message #324876 is a reply to message #324857]

Wed, 04 June 2008 07:09

Michel Cadot
Messages: 68664
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
Account Moderator

Quote:

Is there any drawback of creating a single table cluster?

Yes you have to precisely determine size value otherwise you will either loose space (and increase FTS time) or get overflow block (and increase index access).

Quote:

Can a clustered table be partitioned later

No.

Regards
Michel

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