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Database Forum / DB2 Topics / July 2006COMPRESS .. & VALUES COMPRESSION change request: RFC.
Well known, during "CREATE TABLE" we could optionally specify "COMPRESS SYSTEM DEFAULT" and "VALUE COMPRESSION" options. The main idea about these statements is : NOT to keep on disk the values that can be deduced from some means, isn't it ? The small investigation ( on DB2/LINUX 8.2.3 ) shows these values are compressed: - for numbers (integers,decimals): ZEROs and NULLs (if nullable). - for strings (graphic) : sequences of spaces of any length (0-max) and NULLs (if nullable). Nothing wrong with this implementation, but... The more natural behaviour is expected, like defined in DB2 Reference manual: "... default values used for the data types ... are to be stored using minimal space". The change desirable: instead of skipping default value for "data type", do skip default value for COLUMN in table definition. This change would greatly benefit applications which create huge sparse tables all filled almost single values (like JDE Peoplesoft ERP system). Cheers, -- Konstantin Andreev. > Well known, during "CREATE TABLE" we could optionally specify "COMPRESS > SYSTEM DEFAULT" and "VALUE COMPRESSION" options. The main idea about [quoted text clipped - 18 lines] > This change would greatly benefit applications which create huge sparse > tables all filled almost single values (like JDE Peoplesoft ERP system). DB2 9 has table compression. Customers like VISA have seen huge (like 80%) reduction in size. Cheers Serge  SignatureSerge Rielau DB2 Solutions Development IBM Toronto Lab IOD Conference http://www.ibm.com/software/data/ondemandbusiness/conf2006/ >> The change desirable: instead of skipping default value for "data type", do skip default value for COLUMN in table definition. >> >> This change would greatly benefit applications which create huge sparse tables all filled almost single values (like JDE Peoplesoft ERP system). > DB2 9 has table compression. Customers like VISA have seen huge (like 80%) reduction in size. Excellent ! Waiting for production release of DB2 Viper... -- Konstantin Andreev. Serge Rielau<srielau@ca.ibm.com> 07/06/06 9:02 AM >>> >DB2 9 has table compression. Customers like VISA have seen huge (like >80%) reduction in size. You're probably not at liberty to say, but I'll ask anyway... Assuming you know the answer, does Visa use DB2 to store all online transactions that pass through VisaNet? I was under the impression they used z/TPF for their transaction processing. (Or is there a special version of DB2 for TPF?). Just wondering... we are a VisaNet processor endpoint, but we use VSAM for all of our "card system related" files, for performance reasons. But if Visa uses DB2 I can't imagine any reason we shouldn't also. Frank --- Frank Swarbrick Senior Developer/Analyst - Mainframe Applications FirstBank Data Corporation - Lakewood, CO USA > Serge Rielau<srielau@ca.ibm.com> 07/06/06 9:02 AM >>> >> DB2 9 has table compression. Customers like VISA have seen huge (like [quoted text clipped - 8 lines] > all of our "card system related" files, for performance reasons. But if > Visa uses DB2 I can't imagine any reason we shouldn't also. The data point I gave on compression relates to a data warehouse: http://www.ibm.com/software/data/db2/demo/?S_TACT=105AGX11&S_CMP=VIPER I don't know what they run beyond that on DB2 for LUW and you are correct, if I knew I probably wouldn't be at liberty to say without a quote to point to as in above link. Now that quote does have a name and Ellen is a friendly person. Cheers Serge SignatureSerge Rielau DB2 Solutions Development IBM Toronto Lab IOD Conference http://www.ibm.com/software/data/ondemandbusiness/conf2006/ Serge Rielau<srielau@ca.ibm.com> 07/07/06 12:23 PM >>> >> Serge Rielau<srielau@ca.ibm.com> 07/06/06 9:02 AM >>> >>> DB2 9 has table compression. Customers like VISA have seen huge (like [quoted text clipped - 14 lines] >quote to point to as in above link. Now that quote does have a name and >Ellen is a friendly person. Data warehouse makes sense. I can only imagine (in my nightmares!) how much data they are storing! Thanks for the info and the link. (Now is that a picture of you on that page? <g>) Frank --- Frank Swarbrick Senior Developer/Analyst - Mainframe Applications FirstBank Data Corporation - Lakewood, CO USA > Data warehouse makes sense. I can only imagine (in my nightmares!) how much > data they are storing! *chuckle*Now add Information Integration and Identity Analytics to the mix and you're still playing catch up with reality. Cheers Serge SignatureSerge Rielau DB2 Solutions Development IBM Toronto Lab IOD Conference http://www.ibm.com/software/data/ondemandbusiness/conf2006/ >> The change desirable: instead of skipping default value for "data type", do skip default value for COLUMN in table definition. >> >> This change would greatly benefit applications which create huge sparse tables all filled almost single values (like JDE Peoplesoft ERP system). > DB2 9 has table compression. Customers like VISA have seen huge (like 80%) reduction in size. I've just read "Introducing DB2 9, Part 1: Data compression in DB2 9" from developerWorks. The "table compression" is rather distinct from proposed "column default" compression. How would be interesting to compare the effectiveness... -- Konstantin Andreev. |
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