SUMMARY

This chapter explored different ways of joining data within an SSIS solution. Relational databases are highly efficient at joining data within their own stores; however, you may not be fortunate enough to have all your data living in the same database — for example, when loading a data warehouse. SSIS enables you to perform these joins outside the database and provides many different options for doing so, each with different performance and resource-usage characteristics.

The Merge Join Transformation can join large volumes of data without much memory impact; however, it has certain requirements, such as sorted input columns, that may be difficult to meet. Remember to use the source query to sort the input data, and avoid the Sort Transformation when possible, because of performance issues.