RE: Monitoring occurence of snaphot too old

Why do you have to do this if you can easily unset the optimal settings for the RBS (optimal=null)?

Waleed

-----Original Message-----
Sent: Saturday, August 03, 2002 2:09 PM
To: Multiple recipients of list ORACLE-L

There is another solution for special cases.

Start a transaction in each rollback seg and never commit it. This prevents wraps to the head of the RBS.

I've had to do this with certain SAP operations that run for days at a time, and will generate ORA-1555 if this precaution is not taken. It's suitable for long running jobs where you have no influence with teh duhvelopers.

Details can be found at Steve Adams site, www.ixora.com.au.

Jared

On Friday 02 August 2002 21:13, Mladen Gogala wrote:
> Well, 1555 happens when the query is unable to construct a read
> consistent version
> because rollback segment blocks have been reused by other transactions.
> The only solution
> is to
> a) have sufficiently large rollback segments so that a transaction can
> get unused rollback segment space without reusing recently
> allocated space.
> b) NOT have very long running queries.
>
> Conceptually, in my opinion, the infamous "snapshot too old" comes from
> mixing
> DW and OLTP functions in the same database. A good practice is to have
> a "reporting
> database" as a separate instance and populate it in some way
> (replication, SRDF,
> standby, self written programs). The reporting database can then be
> re-indexed with
> bitmap indexes and used for reports only. Things like that are (now
> this is for DW
> purists) called ODS or opeational data stores and are populated
> approximately once a
> week. Only very small daily reports are run against the main OLTP
> database.
> If you separate your functions like that, ora-1555 will become a
> distant memory.
>
> On 2002.08.02 19:23 Mohammed.Ahsanuddin_at_VerizonWireless.com wrote:
> > Hi,
> >
> > Yes, it is 8i..I was more interested in catching snapshot too old
> > before it
> > happens..does not seem possible..
> >
> > But, my thanks to everyone who responded..
> >
> > Mohammed Ahsanuddin
> > Oracle DBA
> >
> >
> >
> > -----Original Message-----
> > Sent: Friday, August 02, 2002 2:19 PM
> > To: Multiple recipients of list ORACLE-L
> >
> >
> > Yes. I didn't see the version it the other guy's post.
> > Was it 8i?
> >
> > > -----Original Message-----
> > > From: Farnsworth, Dave [mailto:DFarnsworth_at_Ashleyfurniture.com]
> > > Sent: Friday, August 02, 2002 1:54 PM
> > > To: Multiple recipients of list ORACLE-L
> > > Subject: RE: Monitoring occurence of snaphot too old
> > >
> > >
> > > Isn't the UNDO_RETENTION parameter a new one for 9i and does
> > > not exist in 8.x and lower.
> > >
> > > Thanks,
> > >
> > > Dave
> > >
> > > -----Original Message-----
> > > Sent: Friday, August 02, 2002 12:05 PM
> > > To: Multiple recipients of list ORACLE-L
> > >
> > >
> > > Just set the UNDO_RETENTION parameter to 4 hours and forget
> > > about the 'snapshot too old'. It's no longer happening.
> > >
> > > > -----Original Message-----
> > > > From: Mohammed.Ahsanuddin_at_VerizonWireless.com
> > > > [mailto:Mohammed.Ahsanuddin_at_VerizonWireless.com]
> > > > Sent: Friday, August 02, 2002 12:14 PM
> > > > To: Multiple recipients of list ORACLE-L
> > > > Subject: Monitoring occurence of snaphot too old
> > > >
> > > >
> > > > Dear List members,
> > > >
> > > > I was wondering if there is a way to monitor the database and
> > > > tell if there
> > > > is a possiblility of snapshot too old error occurence.
> > > >
> > > > Any input is highly appreciated..
> > > >
> > > > Thanks
> > > >
> > > > Mohammed Ahsanuddin
> > > > Oracle DBA
> > > >
> > > > --
> > > > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > > > --
> > > > Author:
> > > > INET: Mohammed.Ahsanuddin_at_VerizonWireless.com
> > > >
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> >
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Author: Jared Still
  INET: jkstill_at_cybcon.com

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Author: Khedr, Waleed
  INET: Waleed.Khedr_at_FMR.COM

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