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icon5.gif  How doese oracle work when getting some cols from database [message #259256] Tue, 14 August 2007 21:08 Go to next message
lzfhope
Messages: 67
Registered: July 2006
Member
hi,all
I want to know how oracle work when getting some cols from the db. Mostly,We retrive only some cols from a table or a view,those sqls are like this:
select tname from tab;

To surpose,at first,the oracle gets data blocks from disks.In fact .in my conditions, i do not need the whole block,but parts of a block.for example,if the orale get 100 blocks from disk,i only need parts of the first block,the parts of the second block,and ... and parts ot the one hundredth block.
so,I suppose the oracle separates the given datas from all of those block,then return oracle clients those datas.the clients only receice necessary datas from the servers.
is that reasoning right?

Re: How doese oracle work when getting some cols from database [message #259262 is a reply to message #259256] Tue, 14 August 2007 21:39 Go to previous messageGo to next message
BlackSwan
Messages: 25045
Registered: January 2009
Location: SoCal
Senior Member
>is that reasoning right?
yes
Re: How doese oracle work when getting some cols from database [message #259282 is a reply to message #259256] Tue, 14 August 2007 23:05 Go to previous messageGo to next message
Arju
Messages: 1554
Registered: June 2007
Location: Dhaka,Bangladesh. Mobile:...
Senior Member

For more information see about query execution plan.
icon6.gif  Re: How doese oracle work when getting some cols from database [message #259668 is a reply to message #259262] Thu, 16 August 2007 04:15 Go to previous message
lzfhope
Messages: 67
Registered: July 2006
Member
thanks a lot!
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