Re:My Notes on Gitlab's Postgres Schema Design (2022)
by zX41ZdbW on Sunday February 18, 2024 @08:14PM
(#39425231)
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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Re:My Notes on Gitlab's Postgres Schema Design (2022)
by zx8080 on Thursday February 22, 2024 @06:35PM
(#39474871)
> LowCardinality data type does not require the whole set of values to have a low cardinality.
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.