Re: Tuning RMAN: what is rsr_l0key?

Charles

From what I could see, the problemetic query that you mentioned earlier has been clearly identified as a bug 5965453 (On Apr-3rd-07) by oracle support on rhas for 10.2.0.3.

-Rajeev

On 10/12/07, Charles Schultz <sacrophyte_at_gmail.com> wrote:
>
> Since I was not able to get a definitive answer about what rsr_l0key is, I
> did some investigation. This is not rocket science, but I want to share it
> just in case anyone else is curious.
>
> Apparently, rsr_l0key only has relevance when row_level = 2 (also when
> row_type = 'RECURSIVE OPERATION'). When that is the case, rsr_l0key is the
> level 0 key, where rsr_pkey is the level 1 key and rsr_key is the level 2
> key. I think level 2 is the max, at least it is in my database. This is the
> only case where nvl(rsr_pkey,-1) != nvl(rsr_l0key, -1), or to put it in
> english, when the parent key is not exactly the same as the level 0 key,
> even if they are both null.
>
> I am not exactly sure why the rc_rman_status view wants to union in all
> the null level 0 keys. It seems like you would grab all the regular rsr
> keys, and if you want parent information, go get it with a hierarchy or
> something.
>
> However, I am even more perplexed about the original query. Why select a
> session key using a very generic timestamp that has nothing to do with your
> session?
>
> Where are those rman developers when you need to ask completely inane,
> innocuous and inconsequential questions. =)
>
> On 10/11/07, Charles Schultz <sacrophyte_at_gmail.com> wrote:
> >
> > Thanks to those that responded. I thought to make a "group" reply to
> > answer you all at once, but also to make this info available to anyone else.
> > Unfortunately, I have not learned anything else about rsr_l0key; the jury is
> > still out for that one.
> >
> > However, after looking over my SR and hearing back from some of you, we
> > will be applying bug patch 5620640 over the weekend and hopefully that will
> > help.
> >
> > On 10/11/07, Charles Schultz <sacrophyte_at_gmail.com> wrote:
> > >
> > > We are having some serious performance problems with the RMAN catalog;
> > > Oracle suggested that we upgraded to 10.2.0.3 but I think that has
> > > only moved the bottlenecks to different parts of the architecture. Right
> > > now, we are getting killed by this rman query:
> > > SELECT NVL (MAX(SESSION_KEY ), 0) FROM RC_RMAN_STATUS WHERE
> > > SESSION_STAMP < :B1
> > >
> > > Our RC_RMAN_STATUS has ~500 k rows. Looking at the view, there is a
> > > union for rows were rsr.rsr_l0key is null. A third of our rows have a
> > > null value for that column. What is rsr_l0key? It is not documented.
> > >
> > > I am sure our problem is related to volume, but I am not convinced
> > > that this should be the problem. I mean, come on, this is a measly
> > > 500,000 rows.
> > > We are in the progress of creating a colocated catalog to partition
> > > the load a little. But I am still curious about the internals of rman,
> > > especially since it is not documented.
> > >
> > > --
> > > Charles Schultz
> >
> >
> >

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