My New developerWorks Article: Why Low-Cardinality Indexes Negatively Impact Performance

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My second developerWorks article has been published! This is a bit of a technical deep dive into a question that was running around my head earlier in the year. Give it a read and let me know what you think!

Low cardinality indexes can be bad for performance. But, why? There are many best practices like this that DBAs hear and follow but don’t always understand the reason behind. This article empowers DBAs to understand the logic behind why low cardinality indexes can be bad for performance or cause erratic performance. The topics this article covers include B-tree indexes, understanding index cardinality, hypothetical examples of the effects of low cardinality indexes, a real-world example of the effects of a low cardinality index, and tips on how to identify low cardinality indexes and reduce their impact on performance.

http://www.ibm.com/developerworks/data/library/techarticle/dm-1309cardinal/index.html

Figure 4 appears to be missing for some reason. I have notified developerWorks and they are fixing it. In different colors, it looks something like this:
db2_btree_nonunique

Ember is always curious and thrives on change. She has built internationally recognized expertise in IBM Db2, and is now pivoting to focus on learning MySQL. Ember shares both posts about her core skill set and her journey learning MySQL. Ember lives in Denver and work from home

2 comments

  1. Cannot see the full article, any way to solve this?
    after “Figure 4 appears to be missing for some reason. I have notified developerWorks and they are fixing it. In different colors, it looks something like this:”, nothing is there.

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