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Update limit-by.md

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Denny Crane 2022-03-06 13:37:33 -04:00 committed by GitHub
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docs/en/sql-reference/statements/select/limit-by.md
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@ -11,7 +11,7 @@ ClickHouse supports the following syntax variants:
- `LIMIT [offset_value, ]n BY expressions` - `LIMIT [offset_value, ]n BY expressions`
- `LIMIT n OFFSET offset_value BY expressions` - `LIMIT n OFFSET offset_value BY expressions`
During query processing, ClickHouse selects data ordered by sorting key. The sorting key is set explicitly using an [ORDER BY](../../../sql-reference/statements/select/order-by.md) clause or implicitly as a property of the table engine. Then ClickHouse applies `LIMIT n BY expressions` and returns the first `n` rows for each distinct combination of `expressions`. If `OFFSET` is specified, then for each data block that belongs to a distinct combination of `expressions`, ClickHouse skips `offset_value` number of rows from the beginning of the block and returns a maximum of `n` rows as a result. If `offset_value` is bigger than the number of rows in the data block, ClickHouse returns zero rows from the block. During query processing, ClickHouse selects data ordered by sorting key. The sorting key is set explicitly using an [ORDER BY](order-by.md#select-order-by) clause or implicitly as a property of the table engine (row order is only guaranteed when using [ORDER BY](order-by.md#select-order-by), otherwise the row blocks will not be ordered due to multi-threading). Then ClickHouse applies `LIMIT n BY expressions` and returns the first `n` rows for each distinct combination of `expressions`. If `OFFSET` is specified, then for each data block that belongs to a distinct combination of `expressions`, ClickHouse skips `offset_value` number of rows from the beginning of the block and returns a maximum of `n` rows as a result. If `offset_value` is bigger than the number of rows in the data block, ClickHouse returns zero rows from the block.
!!! note "Note" !!! note "Note"
`LIMIT BY` is not related to [LIMIT](../../../sql-reference/statements/select/limit.md). They can both be used in the same query. `LIMIT BY` is not related to [LIMIT](../../../sql-reference/statements/select/limit.md). They can both be used in the same query.