| General Architecture Info. [message #476618] |
Fri, 24 September 2010 03:48  |
muktha_22
Messages: 527
Registered: December 2009
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Senior Member |
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Hi,
please clarify my below basic doubts.
(I've read many Documents, but still need a confirmation)
Eg - My Sql statement is SELECT * FROM DEPT;
1) Now a implicit cursor is created inside the Shared SQL AREA.
2) Now this SQL statement should check whether the same query was already Parsed or not. If it was already parsed then get the answer from BUFFER CACHE. After this steps, the cursor automatically gets closed.
Now where the new SQL statements checks for the existing PARSED query in the SHARED SQL AREA? Is there any exclusive area like HEADER in control file?
3) If the query was already not Parsed then OPTIMIZER will choose, how to execute the statement.
4) Then 'server process' search the relevant Datablock from the Datafile, and placed them inside the Data Buffer Cache.
Will the Buffer Cache store ALL the relevant Datablocks.? (if yes will this also stored the Datablock of Index also)? Or it will store the relevant Data only into the Buffer Cache?
Thanks in advance
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| Re: General Architecture Info. [message #476622 is a reply to message #476618] |
Fri, 24 September 2010 04:19  |
John Watson
Messages: 8962
Registered: January 2010
Location: Global Village
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Senior Member |
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Quote:Now this SQL statement should check whether the same query was already Parsed or not. If it was already parsed then get the answer from BUFFER CACHE. After this steps, the cursor automatically gets closed. From which of the "many documents" did these statements come? How did you reach this interpretation?
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| Re: General Architecture Info. [message #476625 is a reply to message #476622] |
Fri, 24 September 2010 04:38 |
muktha_22
Messages: 527
Registered: December 2009
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Senior Member |
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Hi John,
It is my assumption and ofcourse before taking decision b/w HARD PARSING and SOFT PARSING the Sql statement must check, am I right?
please correct me, where i'm wrong.
Thanks
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| Re: General Architecture Info. [message #476626 is a reply to message #476625] |
Fri, 24 September 2010 04:43 |
John Watson
Messages: 8962
Registered: January 2010
Location: Global Village
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Senior Member |
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No, you aren't right. That's why I wondered what docs you had read. May I suggest attending the Oracle Uni Workshop 1 course, where your tacher will explain what happens during the parse-bind-execute-fetch cycle.
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