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public and private threads (redolog) - differences [message #564556]

Sat, 25 August 2012 12:03

piotrtal
Messages: 168
Registered: June 2011
Location: Poland/Czestochowa

Senior Member

hi everyone.

could you explain me differences of enabling thread as public or private?
i was digging in google but failed completely. :/

lets assume that i have two threads (1, 2) for two instances (1, 2) and each of thread consists of 2 redolog groups - minimum configuration.
in case i need add third node i need third thread.

what will be difference if i set this thread as public instead private?

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Re: public and private threads (redolog) - differences [message #564558 is a reply to message #564556]

Sat, 25 August 2012 13:48

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

what is a thread?
post URL to Oracle manual

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Re: public and private threads (redolog) - differences [message #564559 is a reply to message #564556]

Sat, 25 August 2012 13:51

John Watson
Messages: 8976
Registered: January 2010
Location: Global Village

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Private threads are an historical anomaly. All threads should be public. Do not set the thread parameter.
That's my opinion, anyway.

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Re: public and private threads (redolog) - differences [message #564580 is a reply to message #564558]

Sun, 26 August 2012 03:02

piotrtal
Messages: 168
Registered: June 2011
Location: Poland/Czestochowa

Senior Member

BlackSwan wrote on Sat, 25 August 2012 20:48

what is a thread?
post URL to Oracle manual

w thought about redo thread. each RAC instance have its own redo thread groups. what if happens if i set this thread as private instead public?
what this two values for the redo thread means?
i didn't find answer for this on the net.

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Re: public and private threads (redolog) - differences [message #564588 is a reply to message #564580]

Sun, 26 August 2012 05:31

Michel Cadot
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Registered: March 2007
Location: Saint-Maur, France, https...

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private threads -> only available for the instance that refers it
public threads -> available for any instance but usable only for the first one that takes it.

Regards
Michel

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Re: public and private threads (redolog) - differences [message #564589 is a reply to message #564588]

Sun, 26 August 2012 05:37

piotrtal
Messages: 168
Registered: June 2011
Location: Poland/Czestochowa

Senior Member

Michel Cadot wrote on Sun, 26 August 2012 12:31

private threads -> only available for the instance that refers it
public threads -> available for any instance but usable only for the first one that takes it.

thx Michel for answer.

correct me if i am wrong (lets consider private thread only):

if I set for example redo thread 3 as private for third node, and this third node fails, it means that other remaining instances wont be able to do instance recovery from its (third) threads, because it was set as private?

[Updated on: Sun, 26 August 2012 05:44]

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Re: public and private threads (redolog) - differences [message #564595 is a reply to message #564589]

Sun, 26 August 2012 07:07

Michel Cadot
Messages: 68757
Registered: March 2007
Location: Saint-Maur, France, https...

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No, it means that no other one will be able to use it.
If node 3 fails and then node 5 comes (after node 3 instance recovery is done from an other node) and thread 3 is public then node 5 can use it; if it is private then node 5 can't use it even if node 3 is not there.

But as John said, it is not worth to investigate much time on this point and always use public redo threads.

Regards
Michel

[Edit: missing letter]

[Updated on: Sun, 26 August 2012 08:58]

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Re: public and private threads (redolog) - differences [message #564597 is a reply to message #564595]

Sun, 26 August 2012 07:53

piotrtal
Messages: 168
Registered: June 2011
Location: Poland/Czestochowa

Senior Member

Michel Cadot wrote on Sun, 26 August 2012 14:07

No, it means that no other one will be able to use it.
If node 3 fails and then node 5 comes (after node 3 instance recovery is done from an other node) and thread 3 is public then node 5 can use it; if it is private then node 5 can't use it even if node 3 is not there.

But as John said, it is not worth to investigate much time on this point and always se public redo threads.

thanks Michel (thank everyone) for proffesional answer. now everything is clear, and no sense to set threads as public.
i just asked because didn't know meaning of this parameter. now i know that shouldnt be set as private in RAC environment.

[Updated on: Sun, 26 August 2012 07:54]

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