histograms
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| histograms [2015/08/05 09:40] – [Hybrid Histograms] 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 ==== | ||
| - | This is where the histogram concentrates on only the popular values. | + | 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.\\ |
| - | The less popular values are considered insignificant. | + | |
| + | 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. | 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.\\ | As the name suggests, a combination of Height Balanced and Frequency histograms.\\ | ||
| - | 12c tends to use Hybrid Histograms instead of Height Balanced. | + | 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. | + | The histogram will store the amount of times the highest value is represented in the bucket.\\ |
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| + | [[https:// | ||
histograms.1438767637.txt.gz · Last modified: 2025/03/08 22:23 (external edit)