What is the AgensGraph syntax to specify a mandatory property constraint?

Question

AgensGraph Developer documentation at https://bitnine.net/documentations/developer-manual-en.html#introduction says that the product "Supports Unique, Mandatory, Check constraints". The online help shows the syntax for creating a unique property constraint but not the syntax for a mandatory property constraint. Is such a constraint actually supported?

Answer 1

The Mandatory constraint means that every property must have the key. If users try to MATCH none existing key, AgensGraph returns always NULL. So you can create Mandatory constraints like following example,

CREATE CONSTRAINT ON foo ASSERT bar IS NOT NULL;