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ORACLE DRAMATICALLY AUTOEXTENDS DATAFILE

Good day!

Can you help me with this one?

I have 3 datafiles, all of them are set to autoextend on next 100MB, maxsize is 32GB.

Last october 28 in the morning, those 3 files are extended for a total of 15GB.

Therefore, each datafile was increased to 5GB. When I checked it Oct30, the usage has not grown that much (actually not at all) so how come will the datafile autoextend itself up to 5GB?

I already checked the increment size in Oracle enterprise manager and it says 100MB.

AND.. there are no manual extensions done here. Checked the logs already.

My questions are,

1. Where did that 5GB come from?

2. How does Oracle autoextend its datafile? I just want to know the process.

Fo example,

Autoextend=100MB, MAXSIZE=32GB

If there is a huge data of 15GB and Oracle has to extend the datafile until it has enough space. Does it extends 100MB for 150 times so it can fulfill 15GB? or it will extend 15GB for one time and neglect the 100MB setting for autoextend?

Please I need advices. Thank you!!

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2 Answers

  • Best Answer
    Nov 10, 2017 at 01:50 AM

    Hi Maria,

    Seems this behavior is talked in metalink:

    AUTOEXTEND Grows To Full Size Without Reason (Doc ID 1459097.1)

    The new 11g feature called tablespace extent pre-allocation.

    You can request this document via SAP support incident or you have your own metalink account.

    Best regards,
    James

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  • Nov 14, 2017 at 01:56 AM

    HI James,

    Okay. Got this already! Thanks for your help.

    I see that there is such thing as

    "_ENABLE_SPACE_PREALLOCATION"

    and it is enabled. They call it a hidden parameter.

    http://ksun-oracle.blogspot.jp/2015/12/oracle-bigfile-tablespace-pre.html

    I understand whats happening now. Thanks for your help!

    Have a good day!

    Regards,

    Jhiosa

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