Re: Lose statistics on instance bounce?

>>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<<

On 10/31/00, 1:09:15 PM, Speed Razer <speedrazer_at_NoT SpamM usa.net> wrot e
regarding Lose statistics on instance bounce?:

> Some time back I remember reading a post on Metalink by some guy
> claiming that he preferred hot backups to cold backups because when
> you bounce your instance for cold backups, you lost all your
> statistics. I ran that concept by some other DBAs who said that was
> hogwash. However, I've seen what I believe to be exactly this
> behavior. Namely, if I bounce the instance and don't analyze
> statistics, it takes 4-5 days for the db buffer cache hit ratios to
> climb above 90%. But if I analyze right after I restart the instance,
 

> the hit ratio is usually up to 99% within a day. Any thoughts??
 

> Many thanks,
> SR

  You have two separate issues here:

1. The contents of the V$ views which contain statistical data for

all activity since the database was last started. These are reset when

the database is bounced.

     2. The statistics generated by running the ANALYZE command which are not changed until you next run ANALYZE. It sounds like your db buffer cache is large enough to contain almost all of the active tables

in your system. I say that because of the amount of time it takes to ge t
you hit ratio up to where it peaks. When you run ANALYZE after restarting the database all of the data is being read into the db buffer  

cache, this is why the hit ratio peaks immediately. Received on Wed Nov 01 2000 - 00:03:03 CST