topic Re: Concatenating multiple facts tables into single in QlikView

Concatenating multiple facts tables into single

Anonymous — Mon, 01 Jun 2015 06:38:03 GMT

Hi ,

I would like to concatenate multiple fact tables into single fact table ? which is the best approch Concatenate or can i use left join instead ?

Which is the most preferred with respect to performance ?

Thanks

Re: Concatenating multiple facts tables into single

jonathandienst — Mon, 01 Jun 2015 06:51:44 GMT

They do different things, so it depends on your data and what sort of analysis. To put it simply:

Concatenate adds new rows - in a fact table these are new facts.

Join adds columns to existing rows - this might be enrichment of existing facts

Of course, concatenation can add new columns, but the those columns will be null-valued in the original rows.

And a join can add new rows if the join keys are not unique (or remove rows if an inner join is used), although the existing fields for the new rows will be null valued if they are not part of the join.

Re: Concatenating multiple facts tables into single

deepakqlikview_123 — Mon, 01 Jun 2015 07:04:29 GMT

Hi,

If granularity is same u can concatenate the tables.

Thanks

Re: Concatenating multiple facts tables into single

MayilVahanan — Mon, 01 Jun 2015 07:04:41 GMT

If you have multiple fact table. then go with Concatenate or Link Table.

Concatenate vs Link Table

Re: Concatenating multiple facts tables into single

Anonymous — Mon, 01 Jun 2015 07:17:58 GMT

I have different levels of granularity .Then which is best way

Re: Concatenating multiple facts tables into single

Mon, 01 Jun 2015 07:20:04 GMT

Best Practice is to keep one Fact table which gives faster response.

Concatenate depends on your table structure and granularity. Here Concatenation is very similar to UNION in Sql.

Re: Concatenating multiple facts tables into single

deepakqlikview_123 — Mon, 01 Jun 2015 07:20:43 GMT

Hi ,

You can go with link table.

Create central key table and use the mixture of join and concatenate.

Thanks

Re: Concatenating multiple facts tables into single

Mon, 01 Jun 2015 07:21:51 GMT

If granularity is same then go with Concatenation and if granularity is different then go with Link Table

Re: Concatenating multiple facts tables into single

Asijbty11 — Wed, 07 Oct 2020 18:47:49 GMT

Can you explain how join multiple fact table into one, using Concatenate?

Re: Concatenating multiple facts tables into single

QFabian — Wed, 07 Oct 2020 19:24:59 GMT

try this very old but useful pdf from qlik