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Parallelism
Hi,
Is there any major difference between using PARALLEL hint in the query and using parallelism object level (alter table ...... parallel 4)?
The only difference I can see is, with hint only the query with hint runs in parallel and with object level all the queries hitting that object will run in parallel.
Please correct me If my understanding is wrong.
Thanks,
Vijay Tummala
Try hard to get what you like OR you will be forced to like what you get.
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You are correct.
In our shop we do not like to set parallel degree > 1 by default but in some cases a specific query requires it so we hint it.
Pablo (Paul) Berzukov
Author of Understanding Database Administration available at amazon and other bookstores.
Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.
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Thanks Paul.
Would you mind to provide a scenario where in object level parallelism required by a specific query?
Thanks,
Vijay Tummala
Try hard to get what you like OR you will be forced to like what you get.
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 Originally Posted by vnktummala
Would you mind to provide a scenario where in object level parallelism required by a specific query?
Sure... two scenarios on the top of my mind.
1- Maintenance - During a maintenance window conducting table reorganization I'll certainly hint-parallel the process.
2- Exploratory, one time query - Picture a case where business is asking to run a particular query only once and there is no indexing strategy to support it. Since this is a one time shot it makes no sense to plan a suitable indexing structure so I'll probably schedule such a query to run off hours with a parallel hint on driving table.
Pablo (Paul) Berzukov
Author of Understanding Database Administration available at amazon and other bookstores.
Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.
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Vijay Tummala
Try hard to get what you like OR you will be forced to like what you get.
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