RE: 11gR2 rman compression algorithms
Date: Thu, 4 Sep 2014 18:34:48 +0000
Message-ID: <1E24812FBE5611419EFAFC488D7CCDD126EF42D8_at_G6W2491.americas.hpqcorp.net>
I don’t think the contents of v$rman_compression_algorithm are much help either, but here it is (from 11.2.0.3)
ALGORITHM_ID ALGORITHM_ INITIAL_RE TERMINAL_R ALGORITHM_DESCRIPTION ALGORITHM_COMPATIB IS_ REQ IS_
------------ ---------- ---------- ---------- --------------------------------------------- ------------------ --- --- ---
0 BZIP2 10.0.0.0.0 11.2.0.0.0 good compression ratio 9.2.0.0.0 YES NO NO 1 BASIC 10.0.0.0.0 good compression ratio 9.2.0.0.0 YES NO YES 2 LOW 11.2.0.0.0 maximum possible compression speed 11.2.0.0.0 YES YES NO 3 ZLIB 11.0.0.0.0 11.2.0.0.0 balance between speed and compression ratio 11.0.0.0.0 YES YES NO 4 MEDIUM 11.2.0.0.0 balance between speed and compression ratio 11.0.0.0.0 YES YES NO 5 HIGH 11.2.0.0.0 maximum possible compression ratio 11.2.0.0.0 YES YES NO
6 rows selected.
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Seth Miller
Sent: Thursday, September 04, 2014 1:49 PM
To: Jeremy Schneider
Cc: Oracle-L
Subject: Re: 11gR2 rman compression algorithms
Jeremy,
No, I'm not sure. I copied that text verbatim from the book. The MOS note 563427.1 is probably the closest you're going to get to an explanation. But, I bet Fritz or Tanel could demonstrate conclusively exactly which compression algorithm is being used for each level using OS utilities.
Seth Miller
On Thu, Sep 4, 2014 at 12:43 PM, Jeremy Schneider <jeremy.schneider_at_ardentperf.com<mailto:jeremy.schneider_at_ardentperf.com>> wrote: On Thu, Sep 4, 2014 at 1:22 PM, Seth Miller <sethmiller.sm_at_gmail.com<mailto:sethmiller.sm_at_gmail.com>> wrote:
• HIGH: This level provides the best compression ratio, but consumes the most CPU. (It corresponds to the GZIP compression.)
Just noticed this - are you sure "gzip" is correct? I think the gzip program actually uses the zlib library to do the compression, so that doesn't really make sense.
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Received on Thu Sep 04 2014 - 20:34:48 CEST