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by zX41ZdbW
854 days ago
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The LowCardinality data type does not require the whole set of values to have a low cardinality. It benefits when the values have locally low cardinality. For example, if the number of unique values in `repo_name` is a hundred million, but for every million consecutive values, there are only ten thousand unique, it will give a great speed-up. |
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Don't mislead others. It's not true unless low_cardinality_max_dictionary_size is set to some other value than the default one: 8192.
It does not work well for hundred million values.