histograms
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| histograms [2015/08/05 09:17] – created z0hpvk | histograms [2025/03/08 22:24] (current) – external edit 127.0.0.1 | ||
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| ===== Histograms ===== | ===== Histograms ===== | ||
| ==== Top Frequency Histograms ==== | ==== Top Frequency Histograms ==== | ||
| + | The optimiser normally creates a frequency histogram if the number of distinct values in a column is less than the number of histogram buckets you specify.\\ | ||
| + | This is where the histogram concentrates on only the popular values.\\ | ||
| + | The less popular values are considered insignificant.\\ | ||
| + | Less popular values are therefore grouped together in a single bucket. | ||
| ==== Hybrid Histograms ==== | ==== Hybrid Histograms ==== | ||
| + | As the name suggests, a combination of Height Balanced and Frequency histograms.\\ | ||
| + | 12c tends to use Hybrid Histograms instead of Height Balanced.\\ | ||
| + | The histogram will store the amount of times the highest value is represented in the bucket.\\ | ||
| + | |||
| + | [[https:// | ||
histograms.1438766249.txt.gz · Last modified: 2025/03/08 22:23 (external edit)