RE: 11gR2 rman compression algorithms
- From: "Powell, Mark" <mark.powell2@xxxxxx>
- To: Oracle-L <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 4 Sep 2014 18:34:48 +0000
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@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] 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@xxxxxxxxxxxxxx<mailto:jeremy.schneider@xxxxxxxxxxxxxx>> wrote:
On Thu, Sep 4, 2014 at 1:22 PM, Seth Miller
<sethmiller.sm@xxxxxxxxx<mailto:sethmiller.sm@xxxxxxxxx>> 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.
--
http://about.me/jeremy_schneider
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