Where we use dynamic lookup and where we use it?do we generate surrogate keys u

Where we use dynamic lookup and where we use it?do we
generate surrogate keys using dynamic lookup?can we use it
for scd type 2 mapping and why?

Question Posted / mehul.thakur

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Where we use dynamic lookup and where we use it?do we generate surrogate keys using dynamic lookup?..

Answer / jaspreet banga

Dynamic lookup means the lookup transformation will lookup
in the lookup table during mapping execution using session
i.e.,during runtime, example 'WHEN WE WANT TO GENERATE
PRIMARY KEY AND FOR THAT WE HAVE TO USE UNCONNECTED LOOKUP
TRANSFORMATION FOR LOOKING UP INTO THE TARGET FOR EACH NEW
ROW AND THAT IS DYNAMIC LOOKUP OR RUNTIME LOOKUP'. SCD type
2 indicates history preservation of records i.e.., update
the existing record using last update date and inserting
its new instance with new key. it dosent matter to use with
SCD1 or SCD2 we can use it as per our requirement. one more
example is "loading fact tables by looking up into
dimension tables"

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Where we use dynamic lookup and where we use it?do we generate surrogate keys using dynamic lookup?..

Answer / nayan naik

Dynamic lookup when used in a SCD-2 implementation ,you must
make sure your lookup transformation is on the target table,
hence the dynamic lookup cache is always in sync.

Surrogate keys are generated using a sequence and not a
lookup transformation. Have a look at this link it gives you
a complete step by step implementation of SCD-2 in informatica.
http://deepinopensource.blogspot.in/2013/03/scd-2-implementations-in-informatica.html

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Where we use dynamic lookup and where we use it?do we generate surrogate keys using dynamic lookup?..

Answer / riyaz

The following list describes some situations when you use a dynamic lookup cache:

Updating a master customer table with new and updated customer information. Use a Lookup transformation to perform a lookup on the customer table to determine if a customer exists in the target. The cache represents the customer table. The Lookup transformation inserts and update rows in the cache as it passes rows to the target.

Inserting rows into a master customer table from multiple real-time sessions. Use a Lookup transformation in each session to perform a lookup on the same customer table. Each Lookup transformation inserts rows into the customer table and it inserts them in the dynamic lookup cache. For more information about synchronizing dynamic cache between multiple sessions, see Synchronizing Cache with the Lookup Source.

Loading data into a slowly changing dimension table and a fact table. Create two pipelines and configure a Lookup transformation that performs a lookup on the dimension table. Use a dynamic lookup cache to load data to the dimension table. Use a static lookup cache to load data to the fact table, and specify the name of the dynamic cache from the first pipeline.

Reading a flat file that is an export from a relational table. Read data from a Teradata table when the ODBC connection is slow. You can export the Teradata table contents to a flat file and use the file as a lookup source. Configure the Teradata table as a relational target in the mapping and pass the lookup cache changes back to the Teradata table.

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