| Architecture [message #596237] |
Thu, 19 September 2013 06:26  |
rkkrk2
Messages: 31
Registered: November 2005
Location: chennai
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Member |
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Hi,
I need few clarifications on below concepts:
1. how a table is mapped with a physical drive on server?
2. if there is a materialized view created on emp table with condition ename = 'xyz'.
then when we query for the data with ename ='xyz' it would normally fetch the data from emp table instead of materialized view, what changes in the query would force the db to fetch the data from mview.
3. what are basic 5 types of indexes , i know(btree, bitmap and function based ,cluster what is the other one)?
4. why do we need to migrate from 10g to 11g for what purpose?
Please help me to improve my knowledge on above queries.
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| Re: Architecture [message #596240 is a reply to message #596237] |
Thu, 19 September 2013 06:51  |
cookiemonster
Messages: 13920
Registered: September 2008
Location: Rainy Manchester
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Senior Member |
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1) tables go in tablespaces, tablespaces have 1 or more datafiles on the server.
4) new features, bug fixes and continuing support from oracle.
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| Re: Architecture [message #596241 is a reply to message #596237] |
Thu, 19 September 2013 06:58 |
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EdStevens
Messages: 1376
Registered: September 2013
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Senior Member |
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rkkrk2 wrote on Thu, 19 September 2013 06:26Hi,
I need few clarifications on below concepts:
1. how a table is mapped with a physical drive on server?
The concept of a table is so abstracted from the reality of a physical drive that the question is really meaningless.
A table is a collection of extents,
which are a collection of *logically* contiguous database blocks
which are mapped to addresses within a tablespace
which is an abstraction of one or more data files
which are themselves an abstraction of a collection of locations on a logical volume
which is an abstraction of one or more physical disks.
Quote:2. if there is a materialized view created on emp table with condition ename = 'xyz'.
then when we query for the data with ename ='xyz' it would normally fetch the data from emp table instead of materialized view, what changes in the query would force the db to fetch the data from mview.
If you select from the table, you get data from the table. If you select from the mview you get data from the mview. You control which by specifying which in your FROM clause. A MView is not just some logical concept. It is a very real table occupying very real space. It is just linked to some rules that automatically refresh its contents from other tables.
Quote:3. what are basic 5 types of indexes , i know(btree, bitmap and function based ,cluster what is the other one)?
docs.oracle.com
Quote:4. why do we need to migrate from 10g to 11g for what purpose?
Uh, to maintain support?
Quote:Please help me to improve my knowledge on above queries.
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| Re: Architecture [message #596242 is a reply to message #596237] |
Thu, 19 September 2013 07:09 |
John Watson
Messages: 8931
Registered: January 2010
Location: Global Village
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Senior Member |
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Can you explain the purpose of the questions? I shall assume that you are studying for exams.Quote:2. if there is a materialized view created on emp table with condition ename = 'xyz'.
then when we query for the data with ename ='xyz' it would normally fetch the data from emp table instead of materialized view, what changes in the query would force the db to fetch the data from mview.
You need to read up on query re-write, chapter 10 here, and come back if you can't get it working.
http://docs.oracle.com/cd/E16655_01/server.121/e17749/qrbasic.htm
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