ETL, the process used during the transferring of data between databases is one of the significant concept in data warehousing. This process of ETL consists of sub-processes like Extracting of the data from the source database, transforming the extracted data to the format required to be accepted into the destination database and then finally loading the transformed data into the data warehouse. As this process is done, it is very important to have a quality check so as to confirm that the data is extracted, transformed and loaded in the manner it should be. This article is all about the ETL testing procedure.
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In an enterprise the administration resolutions are taken based on the reports of different employees working on different projects and the reports are all about the data. Hence maintain a proper data warehouse in any company is a must. The ETL is used so as to have a proper correlation between the various databases in various projects so that all the data can be integrated properly. The ETL is a media for communication between the databases through which they can transfer and exchange data through the process of extracting information from a large number of source databases, transforming them into the standard format and then finally delivering them to the required in the destination database.
There are certain differences between database testing and data warehouse testing. The database testing needs lesser volumes of information while data warehouse testing needs bigger volumes of data. In the database testing the information is normally extracted from a similar type of databases but n the data warehouse testing, the data is obtained from a various number of sources f different types. Ordinary databases are utilized in the database testing but deflated ones are used for the other one.
An organization runs well if all the decisions and work culture are done according to a planned strategy. The management has to confirm that all processes are done correctly with proper validation. Hence for having a correct a validated data warehouse, the ETL process has to be quality checked.
While performing the ETL testing, various objections will arise and they are as follows:
• Imperfection in commercial development
• Mismatched and replica information.
• Dilemma happens while construction of test data.
• Testers have no rights to carry out ETL tests themselves
quantity and involvedness of statistics are extremely enormous.
• Absence of wide-ranging test platform
• Failure of information throughout ETL process.
The ETL Testing is important and it is divided into four categories. They are as follows:
• New Data Warehouse Testing: In this testing, the input information is obtained from the consumer necessities and the source databases and also destination databases are developed and then checked using the ETL tools. This testing uses all the fresh databases as the source and destination databases in transferring the data. The fresh information storehouse is developed and then proofreading is done from scratch.
• Migration Testing: In the migration testing, the source database will be the old database of the consumer and then the data is transferred to the fresh destination database so as to have a better efficiency. Database migration testing is required when you shift information from the mature record to a fresh database. The old one is named as the legacy database and also the source and the fresh one is said as the target database and also the destination database. This testing can be done physically but it is too general to employ an automated ETL course to shift the data. Along with the mapping, the old information arrangement to the new one, the ETL tool may slot in the certain set of laws to augment the superiority of data shifted to the destination database.
• Alter Application: In this process, no new database is used. Instead, new data is added which is extracted from different databases and then given to the same data warehouse. Along with the addition of the new information, the consumers may need to add a newer business set of laws for proper development of the data warehouse.
• Report Testing: Reports are the bases depending on which the business decisions are made. They are the output showcase of the projects. It tells about the result of the data warehouse. For testing of this report, proper proofreading of the report, its data and computations are done.
Certain course of actions in the ETL testing is:
1) Production and prerequisite perceptive
3) Assessment evaluation
4) Investigate setting up according to the participation from assessment evaluation and production and prerequisite perceptive
5) Scheming test examples and test situations from every obtainable contribution
6) If all test examples are set, pre-action test and data training are done
7) Finally, implementation is completed till outlet condition is fulfilled
8) Once the total ETL process is completed, a report of it is done and then finishing is obtained.
The steps are:
• authenticate the series and result of ETL batch jobs
• substantiate that ETL processes work with upstream and downstream processes
• Verify the first load of records on data warehouse
• prove any increase in loading of records at a later date for modernized information
• analysis the discarded records that did not succeed ETL rules
• analysis fault records invention
• User Acceptance Testing
Authentications that are required in the ETL Testing are:
a) Confirm that extraction of data is done properly without missing out any data
b) Confirm that transformation phase also works successfully
c) Confirm that in the loading stage, the data is loaded with no cut-off.
d) Confirm that all invalid data is rejected by the destination data warehouse
e) Confirm that replicate information is ignored
f) Confirm that the testing report is correctly generated.
This testing in the ETL process is significant for legalizing and confirming that the production data is correct, dependable and trustworthy reducing the danger of information failure in manufacture.
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