Re: GLOBAL_STATS

Martin Preiss wrote:
> Holger Baer <holger.baer_at_science-computing.de> wrote in message news:<ckj5pl$mp$1_at_news.BelWue.DE>...
>
>
> Hi Holger,
>
> thank you for your comment.
>
> it seems that my conclusions were indeed a little bit fragile ...
>
> The monitoring was set to yes (i think that's default in 10g), the
> tables had been changed, and there were no statistics - while the
> system had statistics for other CTAS-tables that had been created
> about the same time. The only other difference i could see in
> DBA_TABLES was the different entry for GLOBAL_STATS. So i assumed that
> the missing statistics and the GLOBAL_STATS=NO-entry were linked
> together, and that there were no statistics because of the
> GLOBAL_STATS-Setting - which is wrong as i see now: today i have
> statistics on most of the tables and the GLOBAL_STATS have changed to
> yes. I guess the GATHER_STATS_JOB did his job in the maintenance
> window. So everything is fine now.
>
> But i still don't know what's the meaning of GLOBAL_STATS=NO for a
> non-partitioned table. The database reference seems to say that it's
> only of interest for partitioned tables. Or do i misread the
> documentation?
>
> Kind regards
>
> Martin Preiss

Oh, right I forgot to mention - the automatic statistics gathering is somewhen during the night by default. Maybe in the first run not everything got analyzed because the maintainance window was exceeded. I haven't got round to learn all the details regarding this automatic analytics thing (how to configure the maintainance window for a start. Shouldn't be that hard, though).

And my first reaction to the global_stats=no would be: why bother if you don't have a problem? Not very professional ;-), so I did some digging in catalog.sql: If I'm able to count right, then the global_stats field in the end is nothing more than

select decode (bitand(flags, 512), 0 'NO', 'YES') from tab$

So I'd say (until someone with more insight into this things than me corrects me) this flags field, or at least part of it gets set only after statistics have been gathered, so the initial value before the first analyze is indetermined.

Cheers,

Holger Received on Thu Oct 14 2004 - 04:31:33 CDT