RE: Undo segments in a normal tablespace?

  • From: Paul Houghton <Paul.Houghton@xxxxxxxxxxxxxxx>
  • To: Jonathan Lewis <jonathan@xxxxxxxxxxxxxxxxxx>
  • Date: Wed, 19 Mar 2014 16:17:54 +0000

You are right - I was fiddling round with the query and the where clause
dropped off.

I feel suitably embarrassed!

Thanks

PaulH

On Wed, 2014-03-19 at 16:07 +0000, Jonathan Lewis wrote:
> 
> Type 2 is simply the "newer" form of rollback segment - i.e. the thing we're 
> supposed to call an undo segment.
> Your query doesn't show the tablespace_name for the segments - so what makes 
> you think the undo segments are in the same tablespaces as the rest ? It 
> shouldn't be possible.
> 
> 
> Regards
> Jonathan Lewis
> http://jonathanlewis.wordpress.com
> @jloracle
> 
> ________________________________________
> From: oracle-l-bounce@xxxxxxxxxxxxx [oracle-l-bounce@xxxxxxxxxxxxx] on behalf 
> of Paul Houghton [Paul.Houghton@xxxxxxxxxxxxxxx]
> Sent: 19 March 2014 16:03
> To: Oracle L
> Subject: Undo segments in a normal tablespace?
> 
> We were being slightly silly and running a SQL*Plus script to truncate a
> load of tables and load them (insert into table select ... from
> other_table) in parallel over and over again, starting some new scripts
> before the previous one could complete.
> 
> What confused me is that the tablespace was filling up (We got an
> enterpise manager alert). Looking in the tablespace there were a number
> of segments like:
> 
> SQL>  select segment_name, segment_type, trunc(bytes/1048576) as m from
> dba_segments where bytes> 104857600 order by bytes
> 
>   ...
>   SYS_LOB0001312649C00007$$              LOBSEGMENT               2279
>   SYS_LOB0000911233C00007$$              LOBSEGMENT               2311
>   _SYSSMU209_2979571356$                 TYPE2 UNDO               2346
>   XXXXX_TRN_DETAIL                       TABLE                    2357
>   SYS_LOB0001158165C00007$$              LOBSEGMENT               2458
>   XXXXX_CS_SCTY_TMP                      TABLE                    2636
>   _SYSSMU1_1245196837$                   TYPE2 UNDO               2699
>   XXXXXMM_SCTN_DATA                      TABLE                    2813
>   XXXXX_EMAILCOM_INF                     TABLE                    2985
>   XXXXXIT_CALC_TBL                       TABLE                    3088
>   _SYSSMU39_1215612372$                  TYPE2 UNDO               3137
>   ...
> 
> 
> What is TYPE2 UNDO, and how does it end up in a normal tablespace?
> 
> Thanks
> 
> PaulH
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