ETL Processes: Extraction, Transformation, Loading

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Learn the details of the phases of ETL processes: data extraction, transformation and loading, their procedures and security measures.
This article gives you a theoretical overview of each of the phases of ETL processes: extraction, transformation and loading. If you are already familiar with these concepts and want to learn how to choose a tool for ETL processes, you can read the article: " How to choose the most suitable tool for ETL processes? ".
As we told you last week, ETL processes consist of three phases: extraction, transformation and loading . It is necessary to know how each of these processes works and its keys , but it is even more crucial to understand the security measures and precautions that must be taken into account when carrying them out, to prevent the consequences from affecting the system and its normal operation.

The most important aspects of each of these fantuan database are summarized below.







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1. Extraction Process
To correctly carry out the extraction process, the first phase of the ETL , the following steps must be followed:

Extract data from source systems .
Analyze the extracted data by obtaining a check.
Interpret this check to verify that the extracted data conforms to the expected pattern or structure. If it does not, the data should be rejected.
Convert the data into a format ready to begin the transformation process.


What to consider during the extraction process
Extreme caution is required in this phase of the ETL process, which is extraction , so it must be taken into account that:

At the time of extraction, analysis and interpretation : the formats in which the data are presented or the ways in which they are organized may be different in each separate system, since most data warehouse projects merge data from different source systems.

At the time of data conversion : it is worth remembering that source formats are usually relational databases or flat files, but may include non-relational databases or other different structures.
However, the most important consideration would be to always require that the extraction task cause minimal impact on the source system. This requirement is based on practice, since if the data to be extracted is large, the source system could slow down and even crash, making it unusable for daily use.

To avoid this impact and its consequences, in large systems extraction operations are usually scheduled at times or days where interference with the system and its use is null or minimal.