I have a database in which i load fresh data from the source each day. So After 2 days, my qv database is twice the source....
Question: it seems that if I only select one day (each day can be loaded by a field "Key Date") and do a data reduce it is much much faster than when I select a day with a selection box. I thought Qlikview should not make any performance distinction between making a selection and a data reduce. --> I thought qv would not be hindered by the other days (not selected), but apperently the other days not selected make the performance slower....
Well, I may be missing something here, but of course performance is affected differently when you reduce than when you select, because what you are doing when you reduce is removing ("reducing") records from memory. When you select a value from a listbox there is no reduction. If any exclusion of those values not associated with the selected one. But QlikView still has to deal with all records, in fact, it has to exclude or associate.
And viceversa: exclusion doesn't remove anything, all data is there. Reduction does, that's why QlikView performs much better, because of the lower number of records in memory.
If you need to add data daily, and you need to keep all that data, then yes, the size of the document will get bigger.
In addition to what Miguel had said, I'd also recommend looking into your calculations. It sounds like you might have some overly complex calculations that affect your performance.
Even with the size of the document overall bigger, when all the expressions are efficient and relatively simple, there shouldn't be any significant performance penalty when you make a selection. If you feel substantial different, it might be a sign of a problem in your data model or chart expressions.
Try using set analysis instead of If() statements. When possible, Set Analysis performs better off than plan if() conditionals. It takes some time to fully understand the syntax but the work it takes is worth the results you get in regards to performace and cleaner code.
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