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Table index unit Testing

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Posted on by Awaxx

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Hi friends,

I'm a real newbie here.

Here's the point, i m making some corrections on Best Pratices from an internal tool we are working on it.

This tool was developed by many people before i come.

I got to deal with some indexes, got to choose the good one and set up the property to be used correctly (replacement key and so on).

When i will finish this task i was wondering on the way to make some unit test to check if i did it good or not ?

Do you have some ideas on the way to do it ?

Regards.

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Awaxx 229 on at

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Someone for some help please ?
Martin Dráb 241,515 Most Valuable Professional on at

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How to test whether your changes fixed the problem depends on what the problem was. Can you explain it to us, please? We can't tell you much without it.
Awaxx 229 on at

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My problem is first to learn what could be the impact of indexes on tables and related tables ?

Then i wanna know how to choose properties correctly for each kind of behaviours.

And finally how could i use unit test to check if its good ?

I hope i have better explained myself.

Thanks.
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Martin Dráb 241,515 Most Valuable Professional on at

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Indexes may look like a simple topic, but if I want to understand their impact thoroughly, you'll find that it's not actually that simple. You can find a plenty of information on internet, e.g. SQL Server and Azure SQL index architecture and design guide.

In short, indexes improve performance by avoiding the need to scan all data in a table. But keeping the updated takes time and resources (therefore you don't want excessive number and size of indexes). They are also used to enforce data uniqueness. They also have impact on locking.

Before you can test your changes, ask yourself why you added the index. For example, if you did it to enforce uniqueness, you may want to test whether no duplicate records can be created. Or if you did it to solve a performance problem with a query, you may measure performance before and after adding your index.
Awaxx 229 on at

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Thank you goshoom for the answer.

You re right i got to ask myself first what is the purpose of using index.

The reason why using index in my case, is to enforce uniqueness and my actual issue is many errors like "record already exist" or other comparison issues.
Martin Dráb 241,515 Most Valuable Professional on at

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You get "record already exist" if you're trying to save a record that violates uniqueness requirements. It seems that some of your current logic doesn't expect this field (or combination of fields) to be unique.