When is it a good idea to use a custom column over a measure?

[MAwbre]

Question:

Is it better to use a custom column than a constantly performed row-wise measure?  For instance, in a particular table, I have a date column and a time column.  Throughout multiple dozens of measures, I have the date and time being added together row-wise in the measure.  In this case is it better practice to use a custom column to simplify the measure?  Is this a performance concern?  Has anyone measured the performance difference with this particular case?

Background:

I was reading best practices from a number of various sources (which I have unfortunately lost the references to due to receiving a new work computer).  I remember that a common theme was that using measures was a better practice than using custom columns in almost all situations.  I have adopted this methodology and I have to say that I agree to a large extent that it is generally a good practice.

That said, I know of 1 situation already where custom columns are better.  In terms of performance, it is occasionally better to use a custom column for extraordinarily large data sets.  Even then, custom columns are deep down in my steps of optimization, none-the-less they are there.

[v-chuncz-msft · Accepted solution]

@MAwbre,

Here is a good article for your reference. By the way, calculated tables sometimes make things easy.

[MAwbre]

@v-chuncz-msft

Thank you for the article, this is a better description of not simply which is preferred in which situation, but also why.  Applying that knowledge to my situation, I should stick with a measure performing identical calculations within the measure to save on RAM.  That said, since it is performed so frequently, I will simply need to look at the environment it is running in, and determine if the longer CPU time to perform the measure calculation repeatedly is a higher "cost" than the extra RAM by adding a column.

It is unfortunate that I have to sacrifice readability in favor of practicality here.  But at least now I havea  strong udnerstanding as to why.