[resolved] tMap needs to support multiple lookups to the same table (alias)

[Anonymous]

In a Data Warehouse Star schema scenario it is a common requirement to be able to lookup multiple surrogate keys based on the same physical lookup table. Example: A (main) order record may contain the following columns: OrderDate, ProcessedDate, ShippedDate, etc - all needing separate surrogates from a date dimension in the data pipeline. Therefore the Date Dimension needs to be used as a lookup multiple times. In OLAP terms this is called a role-playing dimension. In database terms this is just an alias.
So, rather than duplicating the Date dimension table multiple times as mutiple tInput lookup components, and using up memory, it would be great to use a single tInput lookup component, and in the tMap, be able to alias that single input lookup multiple times, joined from the desired main input. That makes for a simpler design, and should save valuable memory.
Dave

[_AnonymousUser]

And could you explain to me how can I do that on Tmap component ? Thanks in advance

Anyone ?

[Anonymous]

Hi,
It's already exist into our tELTMap you can refer multiple INPUT TABLE for the same using Alias.
Best regards;

Cantoine,
This actually already works using a regular tMap, I successfully used the same table multiple times in a single tmap. Since Talend automatically aliases each lookup, it just treats each instance like another table - works great.
This would make a great webinar.
Dave

[Anonymous]

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and for example, one subject from the list:
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[_AnonymousUser]

I am migrating from datastage to talend. I have a requirement where i am performing 200 reference lookups in 3 lookup stages in a set of 70-70-60 per lookup stage. All the reference lookups for each lookup stage are coming from one source, How should this be implemented in Talend as tmap maps one to one amongst its components.