ALTER TABLE ​

ALTER TABLE changes the definition of an existing table. CoordinatorDB supports adding, dropping and renaming columns, and renaming the table itself.

Supported operations ​

ALTER TABLE table ADD COLUMN column type [constraints]
ALTER TABLE table DROP COLUMN column
ALTER TABLE table RENAME COLUMN old_name TO new_name
ALTER TABLE table RENAME TO new_name

A change must remain valid for existing rows and dependent schema objects. Constraints, indexes, views or triggers can prevent a change that would leave them invalid.

Example ​

Adding a defaulted column ​

CREATE TABLE accounts(id INTEGER PRIMARY KEY);
INSERT INTO accounts VALUES (1);
ALTER TABLE accounts ADD COLUMN status String DEFAULT 'new';

SELECT id, status
FROM accounts
FORMAT csv;

1,"new"

See column operations for the detailed syntax and renaming a table for the rename form. Changing a column's type with ALTER COLUMN TYPE or ClickHouse MODIFY COLUMN is not supported; create a new table and copy explicitly converted values instead.