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About an Oracle's Isolation Levels and lock mode [message #631497] Wed, 14 January 2015 04:25 Go to next message
trybestpro
Messages: 17
Registered: September 2014
Location: HCM
Junior Member
Hi All,
I read document and know Oracle's Isolation Levels have the following categories: Read Uncommitted, Read Committed, Repeatable Read, Serializable.
Oracle's lock mode have the following categories (not all) : ROW SHARE (RS), ROW EXCLUSIVE (RX), SHARE (S), SHARE ROW EXCLUSIVE (SRX),
EXCLUSIVE (X).
But I don't understand what difference of Oracle's Isolation Levels and Oracle's lock mode ?

Thanks all.
Best regards.
Re: About an Oracle's Isolation Levels and lock mode [message #631503 is a reply to message #631497] Wed, 14 January 2015 04:55 Go to previous messageGo to next message
Michel Cadot
Messages: 65849
Registered: March 2007
Location: Nanterre, France, http://...
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Account Moderator

There is no relation between locks and transaction isolation level.
By the way, Oracle does not know "Read Uncommitted" level.

See Database Concepts:
Chapter 9 Data Concurrency and Consistency
Chapter 10 Transactions
Re: About an Oracle's Isolation Levels and lock mode [message #631507 is a reply to message #631503] Wed, 14 January 2015 05:14 Go to previous messageGo to next message
cookiemonster
Messages: 13292
Registered: September 2008
Location: Rainy Manchester
Senior Member
Isolation Levels determine what data you can see when you run a query.
Locks determine what data (and objects) you can modify.
Re: About an Oracle's Isolation Levels and lock mode [message #631510 is a reply to message #631497] Wed, 14 January 2015 05:29 Go to previous messageGo to next message
John Watson
Messages: 7620
Registered: January 2010
Location: Global Village
Senior Member
Are you by any chance from a SQL Server or Sybase background? Those "databases" do have to apply locks to achieve certain levels of isolation because they can't provide read consistency any other way. Oracle isn't like that.
Re: About an Oracle's Isolation Levels and lock mode [message #631513 is a reply to message #631503] Wed, 14 January 2015 07:55 Go to previous messageGo to next message
trybestpro
Messages: 17
Registered: September 2014
Location: HCM
Junior Member
Hi,

My question mean what Oracle's Isolation Levels used to do ? and what Oracle's lock mode used to do ?
I do not distinguish between the functions of the two things above.

Thanks.

[Updated on: Wed, 14 January 2015 07:58]

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Re: About an Oracle's Isolation Levels and lock mode [message #631514 is a reply to message #631513] Wed, 14 January 2015 08:05 Go to previous messageGo to next message
BlackSwan
Messages: 26207
Registered: January 2009
Location: SoCal
Senior Member
trybestpro wrote on Wed, 14 January 2015 05:55
Hi,

My question mean what Oracle's Isolation Levels used to do ? and what Oracle's lock mode used to do ?
I do not distinguish between the functions of the two things above.

Thanks.


which part of below do you NOT understand?

cookiemonster wrote on Wed, 14 January 2015 03:14
Isolation Levels determine what data you can see when you run a query.
Locks determine what data (and objects) you can modify.


Re: About an Oracle's Isolation Levels and lock mode [message #631515 is a reply to message #631514] Wed, 14 January 2015 08:08 Go to previous messageGo to next message
trybestpro
Messages: 17
Registered: September 2014
Location: HCM
Junior Member
BlackSwan wrote on Wed, 14 January 2015 16:05
trybestpro wrote on Wed, 14 January 2015 05:55
Hi,

My question mean what Oracle's Isolation Levels used to do ? and what Oracle's lock mode used to do ?
I do not distinguish between the functions of the two things above.

Thanks.


which part of below do you NOT understand?

cookiemonster wrote on Wed, 14 January 2015 03:14
Isolation Levels determine what data you can see when you run a query.
Locks determine what data (and objects) you can modify.




Hi,
I'm sorry, I want explain my question to Michel Cadot in post #2 Smile Smile

Thanks.

[Updated on: Wed, 14 January 2015 08:09]

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Re: About an Oracle's Isolation Levels and lock mode [message #631517 is a reply to message #631515] Wed, 14 January 2015 08:11 Go to previous messageGo to next message
BlackSwan
Messages: 26207
Registered: January 2009
Location: SoCal
Senior Member
You can lead some folks to knowledge, but you can't make them think.

Enjoy your ignorance!
Re: About an Oracle's Isolation Levels and lock mode [message #631519 is a reply to message #631515] Wed, 14 January 2015 08:29 Go to previous messageGo to next message
Michel Cadot
Messages: 65849
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator

And I gave you 2 links that will explain you.

Re: About an Oracle's Isolation Levels and lock mode [message #631522 is a reply to message #631519] Wed, 14 January 2015 08:32 Go to previous messageGo to next message
BlackSwan
Messages: 26207
Registered: January 2009
Location: SoCal
Senior Member
When all else fails Read The Fine Manual

https://docs.oracle.com/database/121/CNCPT/consist.htm#CNCPT1331

https://docs.oracle.com/database/121/CNCPT/consist.htm#CNCPT621
Re: About an Oracle's Isolation Levels and lock mode [message #631525 is a reply to message #631519] Wed, 14 January 2015 08:36 Go to previous messageGo to next message
trybestpro
Messages: 17
Registered: September 2014
Location: HCM
Junior Member
Michel Cadot wrote on Wed, 14 January 2015 16:29

And I gave you 2 links that will explain you.



Hi,
I thanks for your help. Smile
I'm reading it.

Best regards.
Re: About an Oracle's Isolation Levels and lock mode [message #631526 is a reply to message #631517] Wed, 14 January 2015 08:41 Go to previous message
trybestpro
Messages: 17
Registered: September 2014
Location: HCM
Junior Member
BlackSwan wrote on Wed, 14 January 2015 16:11
You can lead some folks to knowledge, but you can't make them think.

Enjoy your ignorance!


Are you insulting me?
If so, you are very rude and impolite.
You may be more skilled, but does not exist in your ethics.
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