Re: DBA Humor (Twisted, sick sort of stuff...)

  • From: Hans Forbrich <fuzzy.graybeard@xxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Wed, 27 Mar 2013 12:15:25 -0600

On 26/03/2013 3:24 PM, Christopher.Taylor2@xxxxxxxxxxxx wrote:
> Now, having sized these things fairly well, and not having these issues 
> before, I started poking around (of course).
>
> We're under some pretty tight deadlines right now and some of our devs were 
> being really aggressive with their testing.
>
> In the last 1.5 days we've generated over 500GB of archivelogs in this 
> development instance.
Delete generates undo - delete [most] of a huge table, and you end up 
with no data but lots of undo, and as a result, lots of redo.

Oermanent tables to manipulate temporary data generates undo and redo, 
and often get emptied at the end of the transaction.  Global temp tables 
will help with that, eliminating the direct redo although they still 
generate undo and associated redo,  but without the 'clean out' 
transaction undo tracking.  Ultimate size of temporary or working data 
is 'zero', but still has undo and redo.

Index rebuilds generate undo and redo while not changing the data size.

So yup, I can see how you can generate much more undo and redo than you 
hold in live data - especially in a test or dev environment that doesn't 
use flashback database to reset things.

/Hans
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