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how oracle decide which datafile to be used for new extent [message #51834]

Sun, 16 June 2002 13:45

christina
Messages: 9
Registered: November 2001

Junior Member

I have 3 datafiles in one tablespace and only one big table in that tablespace. I found that 2nd datafile has been used 10% even though the 1st datafile has been used only 50% and it has big enough freespace for the next extent of the table. I am wondering that freespace in the 1st datafile will be wasted or oracle will use it later.

Thanks,

Christina

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Re: how oracle decide which datafile to be used for new extent [message #51840 is a reply to message #51834]

Mon, 17 June 2002 06:52

Jyothi Babu B
Messages: 4
Registered: May 2002

Junior Member

Are you sure you have enough maximum chunk of free space to accomodate the extent in the first datafile?
I think in your case, you have enough sum free space, but not the max free space. I hope you understand the difference.

Hope that will help
Jyothi Babu B.

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Re: how oracle decide which datafile to be used for new extent [message #51846 is a reply to message #51834]

Mon, 17 June 2002 12:41

Chrisitna
Messages: 1
Registered: June 2002

Junior Member

I am positive that max bytes from 1st datafile is larger than next extent of the table. and I found that sometimes it allocated next extent on 1st datafile and sometimes it allocated on 2nd datafile. What controls this? By the way, I am using raw lv.

Thanks,
Christina

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Re: how oracle decide which datafile to be used for new extent [message #51949 is a reply to message #51846]

Sun, 23 June 2002 14:37

Jyothi Babu B
Messages: 4
Registered: May 2002

Junior Member

Hi Christie

Oracle uses some specific algorithm to pack the data in to the datafiles. When it has to allocate an extent, it will see what is the suitable available free chunk to accomodate this extent.
For e.g if 10M extent is to be allocated, it will look for some thing little more or equivalent 10M, if it has 20M in datafile 1 and 11M in datafile 2, then it will allocate the extent in datafile 2,but not in datafile 1.

Hope that helps,
Jyothi babu B.

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