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ClickHouse/docs/en/sql-reference/statements/alter/delete.md
olgarev 2aefe5fb77
DOCSUP-790: docs for mutations_sync setting (#12639) 
* Docs in English.

* Fixed links bug.

* Update docs/en/sql-reference/statements/alter/delete.md

Co-authored-by: Ivan Blinkov <github@blinkov.ru>

* Translated into Russian. Anchors in links syncronized with English text. One minor change in English text to unify two similar descriptions.

Co-authored-by: Olga Revyakina <revolg@yandex-team.ru>
Co-authored-by: Ivan Blinkov <github@blinkov.ru>
2020-07-29 09:43:24 +03:00

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39 DELETE

ALTER TABLE … DELETE Statement

ALTER TABLE [db.]table [ON CLUSTER cluster] DELETE WHERE filter_expr

Allows to delete data matching the specified filtering expression. Implemented as a mutation.

!!! note "Note" The ALTER TABLE prefix makes this syntax different from most other systems supporting SQL. It is intended to signify that unlike similar queries in OLTP databases this is a heavy operation not designed for frequent use.

The filter_expr must be of type UInt8. The query deletes rows in the table for which this expression takes a non-zero value.

One query can contain several commands separated by commas.

The synchronicity of the query processing is defined by the mutations_sync setting. By default, it is asynchronous.

See also