Alter Tag/Edge Syntax¶
ALTER TAG | EDGE <tag_name> | <edge_name> <alter_definition> [, alter_definition] ...] [ttl_definition [, ttl_definition] ... ] 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
ALTER statement changes the structure of a tag or an edge. For example, you can add or delete properties, change the data type of an existing property. You can also set a property as TTL (Time-To-Live), or change the TTL duration.
Note: Nebula Graph automatically examines indexes when altering a tag or edge. When altering a tag or edge, Nebula Graph first checks whether the tag or edge is associated with any indexes then traverses all of them to check whether the column item to be dropped or changed exists in the index column. If existed, the alter is rejected. Otherwise, it is allowed.
Please refer to Index Documentation on details about index.
CHANGE clauses are permitted in a single
ALTER statements, separated by commas. But do NOT add, drop, change the same property in one statement. If you have to do so, make each operation as a clause of the
ALTER TAG t1 ADD (id int, name string) ALTER EDGE e1 ADD (prop1 int, prop2 string), /* add prop1 */ CHANGE (prop3 string), /* change prop3 to string */ DROP (prop4, prop5) /* remove prop4 and prop5 */ ALTER EDGE e1 TTL_DURATION = 2, TTL_COL = prop1
Notice that TTL_COL only support INT and TIMESTAMP types.