Difference between extract and loader in ETL

arpit — Sat, 25 Dec 2010 04:06:05 GMT

What is the difference between extract and loader in ETL.

Thanks in advance.
Regards,
Arpit Message was edited by: arpit

Re: Difference between extract and loader in ETL

Cynthia_sas — Sat, 25 Dec 2010 15:14:50 GMT

Hi:
Perhaps using a dictionary would clarify the terms.

For EXTRACT, from Dictionary.com:
"4. to take or copy out (matter), as from a book.
5. to make excerpts from (a book, pamphlet, etc.)."

of course, since you are dealing with Tables in the ETL or DI Studio, what you are "extracting" is data from a SOURCE table. And, as it says in this user group paper:

"The extract node is one of the simplest tools that DI Studio 9.1.3 provides. The code it generates is generally just creating a view as a SQL select."

( http://support.sas.com/resources/papers/proceedings10/039-2010.pdf )

And for LOAD, from Dictionary.com:
"20. to place (film, tape, etc.) into a camera or other device: He loaded the film into the camera.
21. to place film, tape, etc., into (a camera or other device): How do you load this camera?"

Since you are dealing with data tables in the ETL or DI Studio, what you are "loading" is data from a SOURCE table into a TARGET table.

The acronym "ETL" is an industry-wide term -- meaning EXTRACT, TRANSFORM, LOAD. For example, Wikipedia has a very clear description of the concepts:
http://en.wikipedia.org/wiki/Etl

And within the context of SAS, you do the "extracting, transforming and loading" using SAS programs, or using SAS ETL Studio (older product) or using the new product, SAS DI (Data Integration) Studio.

If you are using the older ETL Studio, the user's guide is here:
http://support.sas.com/documentation/onlinedoc/91pdf/sasdoc_913/etl_ug_8238.pdf

On page 6 of the ETL Studio documentation, it has this explanation of the relevant terms:

Extract data from sources such as SAS data sets,
DBMS tables, and enterprise applications.

Transform the data before writing it to the target
data stores. For example, you might change the
structure of your data by joining the contents of
several tables into one table.

Load the transformed data into the target data
stores.

I would suggest that you read the ETL Studio User's Guide (or the DI Studio User's Guide) in order to familiarize yourself with how ETL Studio works and how the terms "extract" and "load" are used in the context of ETL Studio.

cynthia

Re: Difference between extract and loader in ETL

Stuart_sas_pubs — Fri, 07 Jan 2011 19:39:21 GMT

Hi,

Cynthia makes some good points about the differences between the extract transformation and the loaders. You might also look at the latest version of the SAS Data Integration Studio Users Guide here:

http://support.sas.com/documentation/cdl/en/etlug/60948/PDF/default/etlug.pdf

which has a section called "Working with Loader Transformations" in the "Working with Transformations" chapter. This section lists and describes all of the loader transformations available in SAS Data Integration Studio.

Hope this helps,
Stuart Swain
Senior Technical Writer
SAS Institute

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Difference between extract and loader in ETL

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