Re: Q: oracle data files & performance
- From: "Sinardy" <all_about_oracle@xxxxxxxxxx>
- To: <breitliw@xxxxxxxxxxxxx>, <AmihayG@xxxxxxxxx>
- Date: Mon, 1 Aug 2005 15:27:17 +0800
If I am not wrong Oracle randomly get free space regardless how many files
you have, as far as the file is "writable". I think is documented, but I am
not sure.
----- Original Message -----
From: "Wolfgang Breitling" <breitliw@xxxxxxxxxxxxx>
To: <AmihayG@xxxxxxxxx>
Cc: <oracle-l@xxxxxxxxxxxxx>
Sent: Monday, August 01, 2005 2:43 AM
Subject: Re: Q: oracle data files & performance
> At 11:34 AM 7/31/2005, Amihay Gonen wrote:
> >Hi ,
> >I've received a two interesting questions from a collage of mine.
> >
> >1)
> >If two processes are writing to the same file , will they suffer
> >from some conation on the file handler ?
> >Do you think that spreading very busy tables (has a lot of inserts
> >from different sessions) on different tablespaces (which will be
> >translate to different data files ) will have better I/O performance
> >over one single data file ?
>
> In Oracle no two processes write to the same datafile. Writing
> changed blocks to the files is the job of the db writer (dbwr) and
> thus a single process. Even if IO slaves are used, the dbwriter will
> collect all blocks for the same file and give them to a single slave to
write.
>
> >
> >I'm talking only from performance perspective , not from backup &
recovery ?
> >
> >2)
> >If we have tablespaces with several data files . Will oracle
> >allocate extents in a round-robin fashion between the files or will
> >he fill one data file and then pass to the another data file ?
>
> I am not certain of the answer. I have seen indications of both -
> well not exactly both, but uneven growth of the datafiles so not
> exactly strict round-robin extent allocation but also not exactly
> filling one file totally before using the other(s).
>
> Counterquestion - is Oracle a He or a She - or an It or a hermaphrodite
>
>
> Regards
>
> Wolfgang Breitling
> Centrex Consulting Corporation
> http://www.centrexcc.com
>
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> //www.freelists.org/webpage/oracle-l
>
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