oracle total recall

  • From: Remigiusz Sokolowski <remigiusz.sokolowski@xxxxxxxxxx>
  • To: oracle-l <oracle-l@xxxxxxxxxxxxx>
  • Date: Tue, 3 Apr 2012 13:00:50 +0200

hi,

I wonder if anybody used this feature and what are Your impressions?

We turn it on lately on some application and here a little subjective
first look:
- enabling it is easy - point A
- we add data - point B
- first "restore" of previous state was quite fast - point C, logical
state from A
- then we do a little more changes - point D
- and flashback again - point E, logical state from C - this time it
went really long (ie. few days), which puzzles me - it was 15 min. of
changes and flashing them back was longer then creating the database
from scratch (ie. import file)

We assumed this is a penalty for not purging total recall data when in
C, so the next time I did it (ie. purging). This time it seems to run
faster, but I may only dream about the performance of the first time
(ie. C). Sure, the database is founded on some test environment, but not
so bad, I dare to say, though storage is some RAID5, but still wonder...

I saw that flashback goes with db file sequential reads block by block,
so it can not be too fast, but still wonder...

Did anybody notice such characteristic of that feature? Any clever tips
or tricks to speed things up (and I do not mean a faster IO susbsystem,
more memory and faster CPU, but rather suggestion for example to get rid
of flashback archive after every flashback operation and enable it again
or truncate somehow flashback archive system tables with drop storage
option, because I have noticed the segments after purge are of the same
size as before).
Of course there is always an option I did something wrong... (and this
would be also good to know)

Best regards
Remigiusz



-- 
Pole nakazi

----------------------------------------------------------------------
Remigiusz Sokolowski <remigiusz.sokolowski@xxxxxxxxxx>
pos   : DBA at DIiUSI
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