mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-01 12:01:58 +00:00
Update docs/en/sql-reference/statements/optimize.md
Co-authored-by: olgarev <56617294+olgarev@users.noreply.github.com>
This commit is contained in:
parent
977475d7c6
commit
1ebbb8b7bb
@ -31,7 +31,7 @@ When `OPTIMIZE` is used with the [ReplicatedMergeTree](../../engines/table-engin
|
|||||||
If you want to perform deduplication on custom set of columns rather than on all, you can specify list of columns explicitly or use any combination of [`*`](../../sql-reference/statements/select/index.md#asterisk), [`COLUMNS`](../../sql-reference/statements/select/index.md#columns-expression) or [`EXCEPT`](../../sql-reference/statements/select/index.md#except-modifier) expressions. The explictly written or implicitly expanded list of columns must include all columns specified in row ordering expression (both primary and sorting keys) and partitioning expression (partitioning key).
|
If you want to perform deduplication on custom set of columns rather than on all, you can specify list of columns explicitly or use any combination of [`*`](../../sql-reference/statements/select/index.md#asterisk), [`COLUMNS`](../../sql-reference/statements/select/index.md#columns-expression) or [`EXCEPT`](../../sql-reference/statements/select/index.md#except-modifier) expressions. The explictly written or implicitly expanded list of columns must include all columns specified in row ordering expression (both primary and sorting keys) and partitioning expression (partitioning key).
|
||||||
|
|
||||||
!!! note "Note"
|
!!! note "Note"
|
||||||
Notice that `*` behaves just like in `SELECT`: `MATERIALIZED`, and `ALIAS` columns are not used for expansion.
|
Notice that `*` behaves just like in `SELECT`: `MATERIALIZED` and `ALIAS` columns are not used for expansion.
|
||||||
Also, it is an error to specify empty list of columns, or write an expression that results in an empty list of columns, or deduplicate by an ALIAS column.
|
Also, it is an error to specify empty list of columns, or write an expression that results in an empty list of columns, or deduplicate by an ALIAS column.
|
||||||
|
|
||||||
``` sql
|
``` sql
|
||||||
|
Loading…
Reference in New Issue
Block a user