topic Re: Link Table & Concatenation in QlikView

Link Table & Concatenation

vsharma1 — Wed, 25 Nov 2020 16:16:04 GMT

Hello ,

What are the advantages and disadvantages of Link table and concatenation approach?

Re: Link Table & Concatenation

Sergey_Shuklin — Sat, 01 Jun 2019 17:59:28 GMT

Hello!

Here you may find a comparison:
https://www.learnallbi.com/link-table-in-qlikview/
In short words: link table is less memory consuming decision.

Re: Link Table & Concatenation

vsharma1 — Sat, 01 Jun 2019 13:07:10 GMT

why we should not use concatenate method when we have different granularity between fact tables

Re: Link Table & Concatenation

Sergey_Shuklin — Sat, 01 Jun 2019 18:04:01 GMT

Hello!

You may use concatenate for different granularity - it's ok. For instance if you have two same tables - one for months and one for weeks, so you can easily union them. No need to use link table. But, if your tables match only with few fields (customer + country) so the better way is to use a link table with a key.

Re: Link Table & Concatenation

vsharma1 — Sun, 02 Jun 2019 03:15:01 GMT

Hello,

Please add if i miss anything on below

Link table

Advantages:

Should be useful when we have less number of common dimensions available to form a Key between Fact tables

Disadvantage:

Link table may cause performance issue in future due to increase in its size

Concatenation:

Advantages:

Suitable when we have large number of common dimensions between fact tables

Disadvantages:

Consume more memory

Re: Link Table & Concatenation

Sergey_Shuklin — Sun, 02 Jun 2019 06:39:27 GMT

Looks like the goal.
One more advantage of concatenation:
You can use it instead of JOINs for avoiding record multiplying (if you get such cases during tables join).

Re: Link Table & Concatenation

vsharma1 — Sun, 02 Jun 2019 12:24:48 GMT

sorry what you mean by "Looks like the goal" ?

Re: Link Table & Concatenation

Sergey_Shuklin — Sun, 02 Jun 2019 15:46:55 GMT

I meant that is your post about adv / disadv both methods is more than correct and complete. So I call it "the goal" 😃