Concatenating multiple facts tables into single

[Anonymous]

     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

[jonathandienst]

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.

[deepakqlikview_123]

Hi,

If granularity is same u can concatenate the tables.

Thanks

[MayilVahanan]

Hi

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

Concatenate vs Link Table

[Anonymous]

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

[#6]

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.

[deepakqlikview_123]

Hi ,

You can go with link table.

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

Thanks

[#8]

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

[Asijbty11]

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

[QFabian]

try this very old but useful pdf from qlik