Add or Remove a UUID column

An existing table can be altered and a new UUID column can be added. The existing records in the table will have a NULL value for the newly added UUID column. An existing UUID column can also be removed from a table.

Example 5-39 Add a UUID column to an existing table

Use ALTER TABLE to add a UUID column to an existing table.

Create a table test_alter without a UUID column.

CREATE TABLE test_alter(id INTEGER,
                 name STRING, PRIMARY KEY(id))

Output:

Statement completed successfully

Use ALTER TABLE to add a UUID column to test_alter. You can specify the default clause, GENERATED BY DEFAULT.

ALTER TABLE test_alter 
           (ADD new_id STRING AS UUID GENERATED BY DEFAULT )

Output:

Statement completed successfully

Example 5-40 Drop a UUID column

To remove a UUID column from a table, use ALTER TABLE with a DROP id clause.

Note:

You cannot drop a UUID column if it is the primary key, or if it participates in an index.

CREATE Table Test_alter ( name STRING ,
                 id STRING AS UUID GENERATED BY DEFAULT,
                 PRIMARY KEY (name))

Output:

Statement completed successfully

ALTER TABLE Test_alter (DROP id)

Output:

Statement completed successfully