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Sub-setting

SUB-SETTING

Sub-setting DEFINITION

Sub-setting is a method of selecting a predefined data sub-set necessary for testing some particular development iteration of the code at specified environment. The sub-setting is usually performed before anonymization activity happens or in conjunction with the anonymization. Two ways to sub-set are:

1. create a database schema and populate it with partial data set;

2. load a complete production data set and reduce it based on the requirements and the referential constraints.

DEVELOPMENT LIFECYCLE

Let's consider data origination and its moving through the environments in the development lifecycle.

DEVELOPMENT ENVIRONMENT

developing from scratch

Any development starts with the idea, which translates into the code. It is an architectural and development phase of the lifecycle. The code gets tested with the prepared data. The use cases define the data to use and create for the test cases. At the development phase, developers often need to find verified data sources, and the random data masking components contain verified data sets that provide easy means to create such data. Such are Address, First and Last Names, Social Security Number, Credit Card, etc.The 'regular expression' component allows for use of the custom data sets. Use this video as an example of creating a set of random credit card numbers:

Developers could create the rest of the random sets in similar fashion.

The amount of data necessary to do tests in the development phase of the lifecycle is usually the bare minimum. The development testing data ( agile jargon it often would be "unit tests" data) is used mainly for functional requirements verification. Of course, non-functional requirements should be taken into account when creating system architecture, but the time to test them is usually on bigger and more system-like environments than the developer's sandbox.

The development phase and a corresponding environment are used to create the first iteration(s) of code.

developing within mature application

Often times, especially in the big organizations, developers use data of already existing systems. Regardless the type of the development, be it a completely new system or a set of new features for the existing system, the developers would define data necessary for testing as "all the existing master data plus some transactional". They would start with the database schema and a way to populate both master and transactional data sets into it. The easiest way to do it would be to move such data from the existing organization's production systems, master data repositories, etc. If master data repositories do not exist or are not managed in a centralized manner, the way developers would create their own reference sets often times looks the following:

  SELECT  * FROM
(SELECT  ROW_NUMBER() 
    OVER (ORDER BY Country) AS [CountryId], 
    [Country],[CountryCode]
FROM  (SELECT DISTINCT COUNTRY,[CountryCode] FROM [dbo].[Sales]) as Country) AS Countries

Such select creates "country reference data set" and results in the following sample:

CountryId Country CountryCode


1 Canada CAN

2 Mexico MEX

3 United States USA

However, in the denormalized databases, countries and their code and the rest of the entities are often part of the transactional tables. In these cases, developers will select ( sub-set) transactional data based on the use case requirements:

SELECT [Address1], [Address2], [City], [StateProvince], [Country], [ZipCode] 
FROM [dbo].[Sales]
WHERE [Distribution Code] in ('CAN', 'USA', 'MEX')

An above example allows to chose the addresses used in sales per specific region(s):

Address1 Address2 City StateProvince Country ZipCode


1123 Amazing Street #12 Los Angeles CA United States 90001

5438 Cognitive Ave. #99 Toronto ON Canada H0H 0H0

462 San Felipe Blvd. #5 Mexicali BN Mexico 50-57

In the above example, sub-setting is logical and is based on the use case for the specific sales in the specific distribution area.

Sometimes, data definition is not important but the number of records is and then a percentage or a specific number of records define the set:

SELECT TOP 4 [Address1], [Address2], [City], [StateProvince], [Country], [ZipCode] 
FROM dbo.Sales 

This query results in the following selection of rows:

1123 Amazing Street #12 Los Angeles CA United States 90001

1123 Amazing Street #34 Los Angeles CA United States 90001

5438 Cognitive Ave. #99 Toronto ON Canada H0H 0H0

462 San Felipe Blvd. #5 Mexicali BN Mexico 50-57

TEST ENVIRONMENTS

Oftentimes, when an iteration of code development is complete, the developers push the code to the continuous integration environment

and/or to the testers in QA environment. The testers might do testing manually or in automated mode. In such environments, the amount of test cases increases.The testers use these environments to test new features in more detail, to test code regression, and to test certain non-functional requirements such as ease of product use, security, reliability, etc.

Continuous integration environments are used in the teams utilizing best engineering practices based on a method first mentioned by Grady Booch and later adopted by extreme programming agile community. QA or testing environments are either used in manual mode or in automated mode and require significantly more data. The purpose of testing/QA environments is to cover majority of the use cases , new and those already in production that might be affected by the changed functionality. In ideal situation, the complete data set would be needed, yet, moving a complete data set affects the deadlines. Thus, the compromise is to use the records count that goes not in numbers but in different gradations of bytes: MB,GB,TB in this phase of the lifecycle. Oftentimes, testers would need to move to an environment a percentage of the entire data set. The rationale under such sub-setting is a supposition that all main test cases would be covered within certain percent of the data set. On top of that selection, one could add just those test cases that need to be covered in particular. Here is an example of retrieving a percentage of records from the sales table:

SELECT TOP(30) PERCENT [SalesRep], [YearSummary],  [Address1], [Address2], [City], [StateProvince], [Country], [ZipCode] 
FROM [dbo].[Sales]
ORDER BY [Country] DESC

PERFORMANCE TESTING, LOAD TESTING, USER ACCEPTANCE TESTING, AND STAGING ENVIRONMENTS

Let's introduce some definitions to understand the difference in the nuances.

Performance Testing Environment contains a data set that allows to establish benchmarks on system performance metrics, usually those accepted in the industry. It is not used to find functional gaps and bugs.

Load Testing Environment is used to test systems under predefined load patterns. The goals are to find defects in application related to buffer overflow, memory leaks, mismanagement of memory. Another goal is to understand upper limits of load under which the application is still be able to manage its functionality.

In heavy transactional applications, metrics for benchmarking and load include CPU loads, network loads, Disk I/O and memory utilization.

Staging Environment purpose is to stage specific scenario applied to the database / code base as it is currently in production - be it a deployment or a user acceptance.

User Acceptance Testing Environment (or UAT) , as the name implies, allows users test the new version of the application from their perspective, as if they were using the code and data already deployed.

All of the above environments usually require a complete data set.