what is Sparse lookup and what is Normal look up

HariD · Post by **HariD** » Mon Mar 15, 2010 12:13 am

ray.wurlod · Post by **ray.wurlod** » Mon Mar 15, 2010 12:34 am

Moderator: please move to Enterprise Edition (Parallel) forum

These are not Server Edition concepts.

nikhilanshuman · Post by **nikhilanshuman** » Mon Mar 15, 2010 12:41 am

Sparse Lookup : This method is preferred when the rato from source data and reference data is 1:1000.I mean when the source records are very less than the reference records,the Sparce lookup is used.In this way of lookup,for each source record,a query is fired to get the reference data.

Normal Lookup: In Normal Lookup,the entire reference data is loaded into memory first(lookup stage).

ArndW · Post by **ArndW** » Mon Mar 15, 2010 2:04 am

In addition, a sparse lookup, since it is executed for each row as it is read, is also used to read the current value from the source, unlike the normal lookup which has an image of the value from the time it was loaded at the start of the job run.