Re: Tuning RMAN: what is rsr_l0key?
- From: "Charles Schultz" <sacrophyte@xxxxxxxxx>
- To: oracle-l <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 12 Oct 2007 09:06:34 -0500
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@xxxxxxxxx> 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@xxxxxxxxx> 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
>
>
>
>
> --
> Charles Schultz
--
Charles Schultz
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