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Hi,
Suppose i want to join two tables each having 2 columns and a column common in each , what should i perform left join or mapping ?
which is better performance wise ,,my feeling is mapping would be better.
sorry not left join but inner join
mapping is causing slow performance
i suggest you to use inner join
hope this helps
I read in the manual that after mapping the columns, the mapping table gets deleted by itself. So isnt mapping table better then? also, can u tell me why mapping causes slow performance
Hi Vikram,
Join and Mapping are two different things. First you need to think what exactly you need in resulting table. If you want a new column then you require Join . but if you want to update existing column mapping will be needed. Both have their own importance.
Hope I have cleared ur doubts.
Regards
VIjay
Hi Vijay,
Can you give me the example of update?that would be helpful as i am under impression that mapping table is only used add a column to the table like join.
A left join keeps the load optimized. All tested mapping methods BREAK the optimization. This matters. It turns out that a left join is the fastest option for a small number of mapping tables, at least for my sample data (5,000,000 rows, ID field, 10 other fields with values from 0 to 3).
its better to look at http://community.qlik.com/message/114731
hope this helps
You can see it in help tab in QlikView. If still doubt then I will create some example for you.
Regards
VIjay
Also Mapping table can have only 2 columns.
No need dude thanks i got it my mistake ..