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DB2-L - Bedeutung des Prozentsatzes bei "compressed" im DB2 Admin Tool


Re: [DB2-L] - [V1 z/OS] DB2 Administration tool interpretation of information about a table


Bernd Oppolzer <bernd.oppolzer@T-ONLINE.DE>


DB2 List <db2-l@lists.idug.org>


2015.03.09 16:20:00

I forgot about that:

from DB2 SQL Reference:



Percentage of rows compressed within the total number of active rows in the
table. This includes any row in a table space that is defined with COMPRESS YES.
The value is -1 if statistics have not been gathered, or the row describes a
view, alias, created temporary table, or auxiliary table. This is an updatable

Kind regards


Am 09.03.2015 um 16:14 schrieb Bernd Oppolzer:
> just a wild guess on the original question:
> the value 98 % could be the part of the rows that are compressed
> (that is, that have the "compressed" bit on), because not every row
> is compressed ... rows are compressed only, if the resulting length
> is shorter that the original length ... if not (which is possible with
> dictionary-based compression algorithms), the row is stored in
> non-compressed format.
> So the 98 % would tell you nothing about the ratio of compressed size
> to original size ...
> but I don't really know that. I guess that this value comes from a
> SYSTABLES column ... so I would look at the SQL reference manual
> and check if there is a description.
> Kind regards
> Bernd
> Am 09.03.2015 um 15:56 schrieb J.M.:
>> Dear Listers,
>> Infocenter is giving me more headache than information...
>> I am looking at the "Interpretation of an Object in SYSTABLES" panel in the
>> DB2 Administration tool. One of the fields is called "% compressed:" and it
>> shows a value of 98. Now this figure strikes me as odd, because, given the kind
>> of data that is stored in that table, it seems hard to believe that it would
>> compress to only 2 percent of the original size. And if I am reading the figure
>> wrong and need to interpret it inversely, then it is equally difficult to
>> believe that the compressed data would still require 98 percent of the original
>> size...
>> So, naive as I am, I place the cursor on the field and hit PF1, confident that
>> contextual help will kick in and tell me... Big dissappointment... The only
>> thing the help is telling me is that I should look at the DB2 product
>> documentation at http://publib.boulder.ibm.com/infocenter/imzic This now
>> redirects to the IBM Knowledge Center main page, which is equally crap as the
>> Infocenter.
>> Can anyone please tell me where I can find a simple description of the
>> different panels and fields shown by the DB2 Administration tool?
>> Thanks and very best regards,
>> J.
>> P.S. O, did I mention that Infocenter is crap? PLEASE, IBM, give us back Book Manager.
>> -----End Original Message-----

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