Insights into Statistics, Query Optimization and the Oracle Optimizer

How do I get Histogram History?

Nigel Bayliss
Product Manager

Occasionally I want to get historical information on histogram changes for a particular table. I have had a script in my back pocket for a long while so I thought I'd share it in the Oracle Optimizer GitHub repository.

My main motivation for doing this is that I still consider the script experimental and I would like feedback from the field. Feel free to comment below, particularly if you see room for improvement or flaws. Perhaps the output could be clearer or maybe there are cases where the output is incorrect or misleading. I know it would be nice if the script listed histogram type changes but (if I remember rightly) I ran into some difficulty doing that so I stuck to listing bucket count changes instead.

I've seen one or two blog posts on this topic but I've not searched hard to find what's already out there on the web or in MOS. If you are aware of better techniques, then let me know in the comments and I'll consider updating this post.

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