ALTER TAG¶

ALTER TAG alters the structure of a tag with the given name in a graph space. You can add or drop properties, and change the data type of an existing property. You can also set a TTL (Time-To-Live) on a property, or change its TTL duration.

Prerequisites¶

• Running the ALTER TAG statement requires some privileges for the graph space. Otherwise, Nebula Graph throws an error.

• Before you alter properties for a tag, make sure that the properties are not indexed. If the properties contain any indexes, the conflict error [ERROR (-8)]: Conflict! will occur when you ALTER TAG. For more information on dropping an index, see DROP INDEX.

Syntax¶

ALTER TAG <tag_name>
    <alter_definition> [[, alter_definition] ...]
    [ttl_definition [, ttl_definition] ... ]
    [COMMENT = '<comment>'];

alter_definition:
| ADD    (prop_name data_type)
| DROP   (prop_name)
| CHANGE (prop_name data_type)

ttl_definition:
    TTL_DURATION = ttl_duration, TTL_COL = prop_name

• tag_name: Specifies the tag name that you want to alter. You can alter only one tag in one statement. Before you alter a tag, make sure that the tag exists in the current working graph space. If the tag does not exist, an error will occur when you alter it.

• Multiple ADD, DROP, and CHANGE clauses are permitted in a single ALTER TAG statement, separated by commas.

Examples¶

nebula> CREATE TAG IF NOT EXISTS t1 (p1 string, p2 int);
nebula> ALTER TAG t1 ADD (p3 int, p4 string);
nebula> ALTER TAG t1 TTL_DURATION = 2, TTL_COL = "p2";
nebula> ALTER TAG t1 COMMENT = 'test1';

Implementation of the operation¶

Trying to use a newly altered tag may fail because the alteration of the tag is implemented asynchronously. To make sure the follow-up operations work as expected, Wait for two heartbeat cycles, i.e., 20 seconds.

To change the heartbeat interval, modify the heartbeat_interval_secs parameter in the configuration files for all services.