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docs/en/sql-reference/aggregate-functions/reference/count.md
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@ -31,7 +31,7 @@ ClickHouse supports the `COUNT(DISTINCT ...)` syntax. The behavior of this const
The `SELECT count() FROM table` query is not optimized, because the number of entries in the table is not stored separately. It chooses a small column from the table and counts the number of values in it.
However `SELECT count(nullable_column) FROM table` quary can be optimized by enabling the [optimize_functions_to_subcolumns](../../../operations/settings/settings.md#optimize-functions-to-subcolumns) setting. With `optimize_functions_to_subcolumns = 1` the function reads only [null](../../../sql-reference/data-types/nullable.md#finding-null) subcolumn instead of reading and processing the whole table data. The query `SELECT count(n) FROM table` transforms to `SELECT sum(NOT n.null) FROM table`.
However `SELECT count(nullable_column) FROM table` query can be optimized by enabling the [optimize_functions_to_subcolumns](../../../operations/settings/settings.md#optimize-functions-to-subcolumns) setting. With `optimize_functions_to_subcolumns = 1` the function reads only [null](../../../sql-reference/data-types/nullable.md#finding-null) subcolumn instead of reading and processing the whole table data. The query `SELECT count(n) FROM table` transforms to `SELECT sum(NOT n.null) FROM table`.
**Examples**