ClickHouse/docs/en/sql-reference/statements/alter/ttl.md

toc_priority	toc_title
44	TTL

Manipulations with Table TTL

MODIFY TTL

You can change table TTL with a request of the following form:

ALTER TABLE table_name MODIFY TTL ttl_expression;

REMOVE TTL {remove-ttl}

Removes TTL-property from the specified column.

Syntax:

ALTER TABLE table_name MODIFY column_name REMOVE TTL 

Example

Requests and results:

To start the background cleaning using TTL, make this:

OPTIMIZE TABLE table_with_ttl FINAL;
SELECT * FROM table_with_ttl;

As a result you see that the second line was deleted.

2020-12-11 12:44:57    1       username1

ALTER TABLE table_with_ttl REMOVE TTL;
INSERT INTO table_with_ttl VALUES (now() - INTERVAL 4 MONTH, 2, 'username2');
OPTIMIZE TABLE table_with_ttl FINAL;
SELECT * FROM table_with_ttl;

And now we have nothing to delete.

--2020-12-11 12:44:57    1       username1
--2020-08-11 12:44:57    2       username2

See Also

• More about the TTL-expression.
• Modify column with TTL.