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Re: Synchronous writes & TEMP

From: Karsten Schmidt <>
Date: 14 May 2004 12:13:59 -0700
Message-ID: <>

What's the point in using async i/o for temp? you are using the temp tablespace from your session when you run out of ram (i.e. sort_area_size etc..)

You can only continue processing when the write to temp is finished, and the memory is free. So if you were using async i/o to write to the temp segment, what would your session be doing while the write operation is ongoing? -- waiting for it to finished.

Karsten (VC) wrote in message news:<>...
> "VC" <> wrote in message news:<MqIoc.39444$xw3.2544076_at_attbi_s04>...
> > Does anybody know why Oracle uses synchronous writes while writing to the
> > temporary tablespace ? Presumably we do not care about data loss in this
> > case.
> >
> > Your thouhts are much appreciated.
> >
> > VC
> Probably I was being a little imprecise judging by lack of feedback.
> What I am asking here is why Oracle insists on executing synchronous
> write operations whilst writing to the TEMP tablespace. A synchronous
> write means such operation that does not return control to the caller
> until the data is presumed to be safely on the disk. By contrast, a
> non-synchronous write (the 'default') operation returns control as
> soon as the data is transferred to the filesystem cache. The
> rationale for executing synchronous writes against the data files and
> redo logs is obvious.
> I believe (but I may be wrong since I checked only Solaris and Linux)
> that writes to TEMP are synchronous regardless of the OS or Oracle
> version.
> Please do not confuse synchronous writes with asynchronous I/O --
> that's a different beast entirely. I am curious as to why exactly the
> OS write system calls against TEMP are synchronous if data integrity
> is not an issue, that's all.
> Thank you.
> VC
Received on Fri May 14 2004 - 14:13:59 CDT

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