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Inside Buffer Cache [message #476766] Sat, 25 September 2010 15:47 Go to next message
muktha_22
Messages: 527
Registered: December 2009
Senior Member
Hi,

Share your thoughts:
(This is what I understand from 10g Concept pdf - B14220-02)

1) Soft Parsing and Cache Hit are the same meaning?

2) Soft Parsing are happening into the MRU not inside the LRU. Because the MRU only has the recently used Datablocks.

3) if so and the soft Parsing is doing some 'Update'. Then all the relevant Datablocks inside the MRU list will be marked as PINNED?

4) Or for the softparsing also the relevant Datablocks from MRU will be put back to the LRU and after work (Update, Delete..) it will be marked as Dirty buffer and ready to write to 'WRITE BLOCK'?

Thanks in advance
Re: Inside Buffer Cache [message #476769 is a reply to message #476766] Sat, 25 September 2010 16:29 Go to previous messageGo to next message
muktha_22
Messages: 527
Registered: December 2009
Senior Member
Hi,

And what is the relationship with PGA in the above mentioned case.?

Thanks
Re: Inside Buffer Cache [message #476773 is a reply to message #476769] Sat, 25 September 2010 17:40 Go to previous messageGo to next message
BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal
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1) Wrong
2) Wrong
3) Wrong
4) Wrong
5) NO relationship

[Updated on: Sat, 25 September 2010 17:40]

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Re: Inside Buffer Cache [message #476780 is a reply to message #476773] Sat, 25 September 2010 23:51 Go to previous messageGo to next message
Michel Cadot
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Until you read Database Concepts from cover to cover you WILL underdstand NOTHING to Oracle.

Regards
Michel
Re: Inside Buffer Cache [message #476784 is a reply to message #476780] Sun, 26 September 2010 01:13 Go to previous messageGo to next message
muktha_22
Messages: 527
Registered: December 2009
Senior Member
Hi Michel,

(Plz correct me where I'm wrong, so I can continue my reading with that point).

Eg - My Sql statement needed the datablock 1, 5.

1) Now those Datablocks are copied from the datafile to the Free buffer cache of LRU.

2) From there (In LRU), the particular data will be read from those Datablocks, and at this stage those blocks are marked as 'PINNED'. After the work done, those blocks will be moved into the end of MRU.

3) if any other user's Sql statements needed those Datablocks, that will be accessed from MRU, not in the LRU(Because it was already moved to MRU).

4) If the 2nd user's Sql statement is performing any UPDATE, DELETE..., will this be happened at the MRU area or anywhere else.

Thanks
Re: Inside Buffer Cache [message #476785 is a reply to message #476784] Sun, 26 September 2010 01:55 Go to previous messageGo to next message
Michel Cadot
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Please FIRST confirm you read the book I often mentioned.

Regards
Michel
Re: Inside Buffer Cache [message #476787 is a reply to message #476785] Sun, 26 September 2010 02:11 Go to previous messageGo to next message
muktha_22
Messages: 527
Registered: December 2009
Senior Member
Hi Michel,

Yes I read the pdf, but there is nothing mentioned about my above question. please help me to move on....

Thanks
Re: Inside Buffer Cache [message #476789 is a reply to message #476787] Sun, 26 September 2010 02:39 Go to previous messageGo to next message
Michel Cadot
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Please explain what make you think what you think.
Post links to your references.
In addition, why do you need to know Oracle internals which may change from version to version and even patchset to patchset when you are working on a version that is 4 releases back the current one and is no more supported?

Regards
Michel
Re: Inside Buffer Cache [message #476790 is a reply to message #476789] Sun, 26 September 2010 02:50 Go to previous messageGo to next message
John Watson
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Registered: January 2010
Location: Global Village
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Muktha, I've seen a few of your topics on this. The only interpretation I can place on your mis-understandings is that you are confusing PARSE with EXECUTE. You repeatedly describe a parse as reading blocks. As I suggested before, investigate the parse-bind-execute-fetch cycle. And either attend a course, or buy a suitable book. It seems as though the docs are not helping you.
Re: Inside Buffer Cache [message #476870 is a reply to message #476790] Mon, 27 September 2010 01:23 Go to previous messageGo to next message
muktha_22
Messages: 527
Registered: December 2009
Senior Member
Hi Michel,

1) In the above post I had asked what is the relationship b/w BUFFER CACHE and PGA? And u said no relationship.

But in you are another post (message #472315), U had written about PGA.

Can u tell me when PGA is being used along with Buffer Cache?

2) DBWn writes the data buffers back to the Datafile.
When DATAFILE being written back to the DATAFILES? (Not Buffer)

3) Hope when a single data got updated/deleted, the entire Datablock buffer will be
Written back to the DATAFILES. Why it needs to write back the entire Datablock, for a single change?

4) If a Data block present inside the Buffer Cache, so 'ALL THE DATA' of that entire Datablock can be used By any users. Am I right?

Thanks
Re: Inside Buffer Cache [message #476872 is a reply to message #476870] Mon, 27 September 2010 01:29 Go to previous message
Michel Cadot
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1)
Quote:
But in you are another post (message #472315), U had written about PGA.

Post link (once more).

2)
Quote:
When DATAFILE being written back to the DATAFILES? (Not Buffer)

Once again, your questions are cryptic or meaningless or irrelevant. What does this mean? You are not limited in the number of words you can post. So post questions in DETAILS, with links to what you read.

3) If you hope the whole block is written why do you ask why it does it? Smile
Once again this is explained in Database Concepts.

4)
Database Concepts

Regards
Michel

[Updated on: Mon, 27 September 2010 01:30]

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