Consider that direct path event are the ones involve
in f.e. sort_direct_writes=TRUE in 8.0.X or 7.3.X. In
8i doesn't exist as a parameter. However it is feature
included in the engine with default values for their
buffers. Also insert /*+ APPEND */ or sql*loader
direct=y generates that kind of wait. And I don't
think is bad. Although you should take a look of the
paging. Take into account that this wait doesn't use
the buffer cache.
On the other hand as you said increasing the sort area
size doesn't imply an improvement in sorts
performance. You can say it is a matter of paging.
However it is also a matter of the way Oracle resolves
sorting and the merging with the temp tablespace. As a
renmark if you can avoid all the sorting increasing
the sort area you could feel the improvement.
And in the case of the merging with temp tablespace
refer to the sort_multiblock_read_count 8i parameter
Regards.-
--- Johnson Poovathummoottil <[EMAIL PROTECTED]>
wrote:
> We too had a similar problem and thought that we
> should do something to make the sorts faster. But
> investigating a little deeper found the actual
> amount
> of time waited in direct path read/write was very
> little although there are a number waits attibuted
> to
> direct path read and write while sorting. We also
> tried increasing the sort_area_size, but it gave
> adverse performance.
> Of the total time spend for the query cpu time was
> always above 90 percent and wait time was less than
> 10
> %. we executed the same queries on faster cpu
> machines
> and got better results. Also parallelizing the
> queries
> helped.
>
> --- [EMAIL PROTECTED] wrote:
> > How many extents are being written to your
> temporary
> > tablespace?
> > You could increase your sort_area_size if you have
> > the memory.
> >
> > I have seen 1 gig of temp tablespace being chewed
> up
> > reduced to 0 by tuning the sql.
> >
> > You may not always realize that your program
> > statements invoke a sort. Sorting is performed by
> > the following statements:
> >
> > In my case I put an index on the columns in the
> > order by and that took care of the sorts to disk.
> >
> > w CREATE INDEX w DISTINCT
> > w GROUP BY w ORDER BY
> > w INTERSECT w MINUS
> > w UNION w Unindexed table joins
> > w Some correlated subqueries
> >
> > Depending on your system, you can put your
> temporary
> > files on a Raid 1 layout.
> >
> > HTH
> >
> > Mike
> > [EMAIL PROTECTED]
> > On Mon, 09 July 2001, WinterSun_Zhao wrote:
> >
> > >
> > > Hi, DBAs:
> > > I find a process occupy about 50% Cpu. I
> checked
> > the wait event, it was waiting for the event of
> > "direct path write".
> > > I know it is because it is writing to the
> > temporary tablespace. The extent size of the
> > temporary tablespace is 5M, it is temporary.
> > > Would you please tell me how to improve the
> > performance of "Direct path write"? How to
> decrease
> > its cpu occuption.
> > > Thanks!
> > >
> > > WinterSun Zhao
> > > Oracle DBA ( 2 yr+)
> > > Unix SysAdmin ( 4 yr)
> > > [EMAIL PROTECTED]
> > > [EMAIL PROTECTED]
> > > www.pconline.com.cn
> > >
> > >
> > >
> > >
> > > --------
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