topic Re: why to avoid synthetic keys in QlikView

why to avoid synthetic keys

sr_qlikview — Sat, 24 Nov 2012 16:56:49 GMT

Hello All,

I just started learning qlikview,Can some one help me understand why do we have to avoid synthetic keys and how will effect the performance.

Thank you in advance

Re: why to avoid synthetic keys

Gysbert_Wassenaar — Sat, 24 Nov 2012 17:56:09 GMT

See this discussion. In short synthetic keys usually mean you made some mistakes constructing your data model. If you fix the problems of the model the synthetic keys are likely gone as well.

Re: why to avoid synthetic keys

IAMDV — Sat, 24 Nov 2012 20:00:45 GMT

Hi,

Synthetic Keys are always not bad thing to have. Although, as a rule you should avoid them and work on your model. You can use Hash128() and Autonumber() functions to build concatenated field keys. These functions are less rescource consuming.

Cheers,

www.QlikShare.com

Re: why to avoid synthetic keys

hic — Sun, 25 Nov 2012 00:08:20 GMT

Just as Deepak indicates in his last post, synthetic keys are not always bad. Rather, you should ask yourself "Do I want two keys between these two tables?".

If yes, then you could leave it as it is or create a composite key with Hash128(Key1 & Key2) or Autonumber(Key1 & Key2). Either way, it will improve the data model. (If the synthetic affects3 tables, a composite key may be necessary.)

But if you don't want two keys, one of the keys should be removed by renaming a field.

HIC