RE: Global Temp Tables and Indexes

Bruce,
 When the 1st row is inserted into GTT, Oracle will acquire the temp segment in user's temporary tablespace and that will be reflected in v$sort_usage. However, it will continue to hold the table's data in the PGA of the session within the sort areas rather than in the data base buffer cache. When sort_area_size worth of data is collected, it will be written to the already acquired temp segment using the extent pool algorithm. Compare this to how 'create table' with initial extent works, where a table segment is created first, to be followed by inserts. Only in this case, 1st insert operation creates the 'extent' but actual data is inserted at a later stage, if required.
Hope this helps.

Regards,

• Kirti Deshpande Verizon Information Services http://www.superpages.com

> -----Original Message-----
> From: Reardon, Bruce (CALBBAY)
> [SMTP:Bruce.Reardon_at_comalco.riotinto.com.au]
> Sent: Wednesday, June 27, 2001 8:30 PM
> To: Multiple recipients of list ORACLE-L
> Subject: RE: Global Temp Tables and Indexes
>
> Kirti,
>
> I am running 81712 on NT4 with a 1MB sort_area_size and a 1MB
> sort_area_retained_size.
>
> As soon as I insert 1 row into a 6 column GTT (
> VARCHAR2(2),NUMBER(5),NUMBER(5),NUMBER(8),VARCHAR2(1),DATE) I see a record
> appear in v$sort_usage.
> In testing, this the first thing I do as soon as I connect and I do not
> have
> a login script that runs any sorts.
>
> Why might this be (ie why isn't the row held entirely in the PGA given the
> 1M sort_area_size)?
>
> I altered the system's sort_area_size to 10M and reconnected and still
> after
> inserting just 1 row I see a record in v$sort_usage.
> I get the same behaviour regardless of whether the temp tablespace has
> temporary or permanent contents.
>
> Thanks,
> Bruce
>
>
> -----Original Message-----
> Sent: Thursday, 28 June 2001 11:06
>
> Jack,
> Those rows will be stored in session's PGA in the sort areas
> (sort_area_size). When you insert more rows to fill up sort_area_size, you
> will see the table using your temporary tablespace. Or you can alter your
> session to use much smaller sort_area_size. Also, you can check
> v$sort_usage view to see how the numbers change as you add to the GTT.
>
> Hope this helps,
>
> - Kirti Deshpande
> Verizon Information Services
> http://www.superpages.com
>
> > -----Original Message-----
> > From: Jack C. Applewhite [SMTP:japplewhite_at_inetprofit.com]
> > Sent: Wednesday, June 27, 2001 7:01 PM
> >
> > Hi,
> >
> > Using Oracle8i 8.1.6...
> >
> > I've created a Temp table and inserted a couple of rows, but there seems
> > to
> > be no way to verify that it's segment(s) is(are) in the temp tablespace
> of
> > the creating user. I've looked at every USER*, DBA*, and v$* view I can
> > find - Tablespace_Name is null in all of them. I inserted the rows
> > because
> > I know that the first extent of a temp table is not allocated until the
> > first insert.
> >
> > I'd like to see that the segment is where I think it is because I want
> > another user whose temp t.s. is on another drive to create an index on
> > that
> > table. That's the only way I can think of to get an index on a temp
> table
> > in another tablespace - for performance considerations.
> >
> > Anybody know how to verify the tablespace? Will my proposed method for
> > getting the temp index on the temp table on another drive work? Any
> > suggestions?
> >
> > Thanks.
> >
> > Jack
> >
> > --------------------------------
> > Jack C. Applewhite
> > Database Administrator/Developer
> > OCP Oracle8 DBA
> > iNetProfit, Inc.
> > Austin, Texas
> > www.iNetProfit.com
> > japplewhite_at_inetprofit.com
> > (512)327-9068
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Reardon, Bruce (CALBBAY)
> INET: Bruce.Reardon_at_comalco.riotinto.com.au
>
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Deshpande, Kirti
  INET: kirti.deshpande_at_verizon.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
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