Re: High RBS usage during INSERT operation.

vikram.kale_at_gmail.com wrote:
> Hi
>
> I have noticed that rollback segment usage is 7 times more compared to
> the actual table size. The table size is 350mb whereas the transaction
> involving INSERT statement has taken 2500mb. Any thought?? (no indexes,
> only data)
>
> regards,
> VK

How exactly are you measuring the usage? Can you look at v$undostat?

How exactly are you doing the insert?

See
http://asktom.oracle.com/pls/ask/f?p=4950:8:::::F4950_P8_DISPLAYID:6894817116500

Certain configurations on certain versions can cause excessive undo usage, please remember to give specific version information. Are you using undo_retention?

I've found this can be helpful (from some metalink note I think, but I've lost the reference):

select

   substr(a.os_user_name,1,8)    "OS User",
   substr(a.oracle_username,1,8) "DB User",
   substr(b.owner,1,8)  "Schema",
   substr(b.object_name,1,20)    "Object Name",
   substr(b.object_type,1,10)    "Type",
   substr(c.segment_name,1,5)  "RBS",
   substr(d.used_urec,1,12)      "# of Records"

   v$locked_object a,
   dba_objects b,
   dba_rollback_segs c,
   v$transaction d,
   v$session e
where a.object_id = b.object_id

   and a.xidusn    =  c.segment_id
   and a.xidusn    =  d.xidusn
   and a.xidslot   =  d.xidslot
   and d.addr      =  e.taddr

/

jg

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