Oracle Scratchpad

October 15, 2018

Histogram catalogue

Filed under: Histograms,Oracle — Jonathan Lewis @ 1:37 pm BST Oct 15,2018

This is a list of all articles I’ve written about histograms. Each entry has a date stamp and a short note of the contents. The articles are grouped in a couple of different categories (mainly because this note started life as a list articles on faking the different types of histogram), but otherwise are generally listed most-recent first.

General Articles

Faking histograms

  • Hybrid Fake (Oct 2018): How to create a hybrid histogram (using a character column for the example).
  • Column Group Histograms (Aug 2018): faking values into a histogram for a column group – only special because we need to derive the value stored.
  • Column Group Histograms (Jul 2018): Hacking options to solve a live problem
  • Histogram Tip (Sept 2015): An example of creating a simple character-based frequency histogram (published in the IOUG Tips booklet 2014).
  • Faking a height-balanced histogram (March 2010): How to create a height-balanced histogram (using a numeric column for the example).
  • Faking a frequency histogram (May 2009):  How to create frequency histograms (using a numeric column for the example)
  • Top frequency:  I haven’t yet worked out how to fake a Top Frequency histogram. Since it’s little more than a frequency histogram where the optimizer knows there’s a further small percentage (less than one bucketful) of other data, this doesn’t worry me; if necessary I’ll just create a “good enough” frequency histogram and set a suitable density for the remainder.

Articles for redgate/Simpletalk

  • Histograms part 1 – Why? (Aug 2013) – why we might need histograms and the types of histogram available to Oracle.
  • Histograms part 2 (Oct 2013) – the problems and workarounds for some cases where a height-balanced histogram may be a liability rather than a help.
  • Histograms part 3 – When? (Oct 2013) –  examples of using height-balanced histograms to work around design errors.

Other authors


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