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What is Loading in ETL Process of Data Warehousing?

Data Extraction in Warehousing:

The data extraction determines a process to capture data from a source for further usage in the data warehouse environment. It kick-starts data mining, which scales around extract, load and transform data. Upon capturing, the data are rearranged, reformatted and cleansed properly. Together with all, they compose the ETL process.

Mostly, transaction processing, CRMs or business directories are drilled as sources. Mostly the data extraction services providers find it challenging, which may take a long time to be effectuated.  It requires proper designing and execution of the extraction process. The complex & poorly structured sources can take a lot of time.

Its sources are frequently drilled to satisfy data requirements of different parameters. This is why a set of data is churned and scraped unless the miner gets data for all conditions. Besides, the data extractors upgrade the entire database over a time to meet the need of warehouse.

Extraction Specifications:

The ultimate motto of scraping data is to cleanse and transform database into usable information. This information stems business intelligence. Thereafter, its technique like data flow diagrams comes into play. If you consider interviews or reports as an input, extracting the information according to parameters is a big deal. The conversation is hard to mould accordingly.    

While designing the pan extraction process, these aspects should be underscored:

- The method that you are going to choose is vital. It impacts the source system, transportation process and the time needed for upgrading the warehouse.

- The way to provide the extracted data for further processing defines its transportation method. It directs for cleaning and transforming data.

Data Loading in the ETL Process:

The final decision or intelligence is crucial. It needs to be processed properly for loading sans any friction. Then, an SQL select statement is run for loading:

- Choose target column list

- Select where to join

- Filter the group wise list

- Sort order  by aggregate list

Multiple passes of data:

This pre-loading phase irons out all difficulties in pulling data from multiple systems. Being driven from different CRMs or databases, they need to be compiled. This compilation might involve calculations and transformations for placing into a preset model of a warehouse.

Let’s say, the marketing predictive analysis requires marketing insights, trends, buying and web journey and inventory/ order status.  The extractor will communicate with all these databases to pull and merge all data entries in a data sheet. 

Staging area:

This phase is about setting and defining a staging area. This area offers a temporary work area to carry out cleaning of data. With the help of a developer, the scraper maximizes the uptime of data warehousing. This very area can be harnessed to manage source data, which will be further processed for data warehouse transactions. 

Checkpoint restarts logic:

This method has been around for many years to process batch on mainframe computers. It defines the point to restart the pan cleansing & extraction process. Simply say, it resets the process at the point where a long running process fails to complete, instead of beginning from the scratch. The logic will remain the same. But, the necessary monitoring steps for transformation should be predefined in the staging area.

To prevent restarting from scratch, the developer takes an input variable. This variable determines where the process should begin from. Let’s say, a process has 10 steps and the failure occurs in the 8th step, the process will restart from 8th step, rather than the 1st step.

Data loading:

Now, you have the extracted data. They are all set to be loaded into a warehouse. They are cleansed and reformatted to meet the warehouse standards. Now, you can compile them with residing data entries as per set criteria.

However, that data may need to undergo a reformatting as per specification. Subsequently, the data inventory refines within the metadata warehouse. The changes reflect after accomplishing the entire loading process.