Re: Pluggable database in 12C
Date: Thu, 18 Oct 2012 10:22:51 +0100
Message-ID: <u8qdnR8z8v6sV-LNnZ2dnUVZ8g-dnZ2d_at_bt.com>
"Noons" <wizofoz2k_at_yahoo.com.au> wrote in message news:k5ogqf$bds$1_at_dont-email.me...
|
| Last bit of info I have indicates they got it completely wrong: all PDBs
share
| the same container redo log set! Talk about contention...
| One of the *biggest* advantages MSSQL has in this field is that it is
possible
| to optimize I/O for each PDB log set.
| With 12c if it stays with a global redo log? Ah yes, of course: buy
Exadata!
| That's gonna work really well...
|
That was such an obvious design flaw that I raised it at (I think) one of the Engineered Systems breakfast seminars.
The point I made was in reply to the "you only need one of each background process for the whole system rather than one of each for each database."
The follow-up answer to this was that you are able to define multiple log writers (not just I/O slaves for a single log writer). At that point I should have asked whether these multiple writers would behave like the multiple log writers you get in RAC, viz: separate log file groups that have to be resynchronized on recovery - but I didn't ask that question because it was such an obvious implementation detail that I didn't even think about thinking about it.
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com/all_postings
Author: Oracle Core (Apress 2011)
http://www.apress.com/9781430239543
Received on Thu Oct 18 2012 - 11:22:51 CEST