I should probably expand on the "good DB design" statement. Take, for example, your second suggestion with the tags in Attr 1 and values in Attr 2 onwards. Once this system is implemented, how do you add and future fields that need to be catered for, such as created/modified timestamps for items, or worse, each tag in the item? Since you have already assigned all possible attributes 1-n you need to either create another file or rework all programs that use it.
In the "flattened" solution I offer, it is a trivial exercise. I say this because we have a 15 year old system here that suffers from this issue and it causes as many headaches. I wish we had a system that used "pick style" where and only where it was appropriate. -----Original Message----- From: u2-users-boun...@listserver.u2ug.org [mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Dan McGrath Sent: Friday, 10 December 2010 3:18 PM To: U2 Users List Subject: Re: [U2] Sparse array population in Pick 100% agree, but "this is pick" doesn't mean disregard all rules of good DB design. Fair enough, MVDBs are designed around not subscribing to the "1st norm form rule"; we should still present out data in the most structured manner possible, for this will give us the greatest flexibility if/when the system needs to be expanded. As I said though, it all comes down to how you need to work with your data. My form is not the most efficient for random access of individual items, but it does give you the flexibility of being able to sort and select on tag/value pairs. Additional benefits are that I could also index on tag names if required, which neither of the your original proposals can. I reiterate though, design all comes down to the intended purpose. Similar situations happen in SQL where you need determine if/where/how much you should denormalize your data. Work out the most important requirements/future requirements for your system and develop accordingly. -----Original Message----- From: u2-users-boun...@listserver.u2ug.org [mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of fft2...@aol.com Sent: Friday, 10 December 2010 2:00 PM To: u2-users@listserver.u2ug.org Subject: Re: [U2] Sparse array population in Pick But Dan you're just flattening the array. Boooo This is Pick! The point of a method of populating a sparse array is to address the efficient storage of data when your array is sparse. In your method, you'd have to do several disk reads in order to collect all the tags for one item in one spot. The method I displayed, is a single disk read :) _______________________________________________ U2-Users mailing list U2-Users@listserver.u2ug.org http://listserver.u2ug.org/mailman/listinfo/u2-users ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________ ######################################################################## ################### The information transmitted in this message and attachments (if any) is intended only for the person or entity to which it is addressed. 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