Re: Lose statistics on instance bounce?

I think I just answered my own question: I also run a cron job a couple of hours before the cold backup that rebuilds a bunch of the indexes which would explain why, if I don't re-analyze, my stats are stale. Duh! Thanks for your help, SR

On Tue, 31 Oct 2000 12:40:51 -0600, "Kevin Brand" <kevin.brandx_at_tel.gte.com> wrote:

>
>Are you looking at hit ratios since startup during that initial 4-5 days?
>If so, try taking a snapshot over a smaller amout of time using either
>utlEBstat or your own CACHE tool. That is, after the first several hours
> or 1 day ) after a bounce of the instance, take an hour long sample during
>a busy time and calculate your hit ratios off of the sample.
>
>Bouncing the instance certainly clears the buffer cache AND all of the
>v$sysstat "statistics", but it does NOT clear table/index statistics
>generated by calls to ANALYZE.
>
>-Kevin
>
>
>"Speed Razer" <speedrazer_at_NoT_SpamM_usa.net> wrote in message
>news:4j1uvs8o380b9h8pr2s7jioc9vsrvkp7ue_at_4ax.com...
>> 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
>
  Received on Tue Oct 31 2000 - 13:18:10 CST