Re: Pluggable database in 12C

From: Jonathan Lewis <>
Date: Thu, 18 Oct 2012 10:22:51 +0100
Message-ID: <>

"Noons" <> wrote in message news:k5ogqf$bds$
| Last bit of info I have indicates they got it completely wrong: all PDBs
| the same container redo log set! Talk about contention...
| One of the *biggest* advantages MSSQL has in this field is that it is
| to optimize I/O for each PDB log set.
| With 12c if it stays with a global redo log? Ah yes, of course: buy
| 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.


Jonathan Lewis

Author: Oracle Core (Apress 2011) Received on Thu Oct 18 2012 - 11:22:51 CEST

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