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I came across the following sentence in this blog post:

Know your data - this helps you make the right decisions in terms of data types/nullability and churn helps with long term maintenance goals (and initial maintenance plans)

I can't figure out what is meant by "churn." What is this? I only find plenty of articles talking about "churn" without saying what it is.

Evan Carroll
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Kolja
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3 Answers3

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"Churn" in the most common usage is the rate that existing members of a group leave the group (for example, customers of a company stop being customers- if a company has 15% annual churn, 15% of its customers leave every year).

In this context, then, it would seem that the author is saying that you have to understand the rate at which records may be deleted or otherwise removed from tables in order to understand how to best plan the maintenance of the system.

Thomas Cleberg
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  • Ah, I see now how this seems to be meant. I tried to understand churn and I found it in the dictionary with a definition like yours but in the grammatical context it just didn't make sense. I guess the author forgot a word or something, and so I got totally stuck. Especially as this sentence is highlighted as one of the key statements, and I couldn't make sense of it. Thanks! – Kolja Dec 31 '14 at 14:53
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If I was to use a phrase that I think of when I hear (and use) the words data churn, I think of the following:

Data Modification

Thomas Stringer
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Think inserts, updates, and deletes. Things that cause the data in a given table to change. If you know the amount of churn, you can use that for a relative proxy on index maintenance costs (overhead).

Mr.Brownstone
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RobM
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