Lookup's are a key component in SQL Server Integration Services (SSIS). Explain its purposeSSIS 2008 has the ability of cache lookup data in to a local file. Lookup data thus needs to be retrieved once, and then cached and reused. Lookups are a way to provide a range of values for a particular column’s value. It is very useful while transforming data and cleaning it as well. Lookup enables transforming of data from one table to another and merging tables as well through a range of values. This can clear and clean a lot of misspelled data. Example: A table might have flrida stored as city instead of florida. If the transformation is made through a lookup consisting of Florida, then flrida will be converted to Florida, providing a clean transformation.
Lookup's are a key component in SQL Server Integration Services (SSIS). Explain its purposeLookup transformation combines data from two sources. The fields of these sources are matched. The lookups performed by the transformation are case sensitive. The lookups are used to access additional information in a related table that is based on values in common columns.
Lookups are used for the following purposes:
1. Lookup transformation
2. Looking up data in data warehouse
3. Looking for the key that’s different in the DW
4. Inferred members
5. Inferred members in the error output in the lookup
6. Slowly changing dimensions
7. Type two slowly changing dimension
8. Optimizations - Cache mode: full cache, partial cache, no cache