Re[2]: Numerics PACKED, ODD format -- Always recommended?

[ericadelong@xxxxxxxx]

DB2 stores numeric data exactly as specified in DDS (except for date, time, and 
timestamp types). Zoned fields use 1 byte per digit, Packed uses the over/under 
format (with the last nibble reserver for sign) yielding (bytes*2)-1 digits. 

PGMs on the AS400 internally default numeric data to packed, translating zoned 
fields before use. Even length packed fields require the first nibble to be 
zero, which has no impact on DASD, but which does slightly impact performance.

Eric A DeLong
ericadelong@pmsc.com  
_____________ Reply Separator ________________

Bob Crothers wrote:
> 
> Karen,
> 
> Yes, it is best (from a performance point of view) to use odd 
> length packed numeric data in your files.
     
     
Doesn't db/400 ignore the packed vs. zoned definitions now?  I thought 
all numeric fields were packed regardless of what one writes in the dds. 
About the odd vs even issue: if you need 8 characters, then you need 8 
at least so you can't go to 7.  My understanding always was that the 
cycles for 8 are the same price as the cycles for 9, so the 9th 
character is a freebie, excepting dasd.


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