Sets

A set is similar to an array, but deduplicates items.

DEFINE FIELD visited ON TABLE traveler TYPE set<record<country>>;
CREATE traveler:one SET visited = [country:canada, country:usa, country:korea, country:japan];
-- Traveler comes back from a trip
UPDATE traveler:one SET visited += country:uk;
-- And again
UPDATE traveler:one SET visited += country:uk;

Response
[
	{
		id: traveler:one,
		visited: [
			country:canada,
			country:usa,
			country:korea,
			country:japan,
			country:uk
		]
	}
]

Internally, a set is identical to an array – even inside a schema definition. The only difference is that a field defined as a set will never hold a duplicate item. Otherwise, a field defined as an array can take a set as input and vice versa.

DEFINE FIELD bank_accounts ON TABLE customer TYPE set<int>;
DEFINE FIELD languages ON TABLE customer TYPE array<string>;

CREATE customer SET
    bank_accounts = [
      55555,
      55555,
      98787
    ],
    languages = <set>[
        "en",
        "ja",
        "kr",
        "kr"
    ];

Output
[
	{
		bank_accounts: [
			55555,
			98787
		],
		id: customer:uv6mn62t8td9vzvfogh4,
		languages: [
			'en',
			'ja',
			'kr'
		]
	}
]

Casting into a set can be a convenient way to deduplicate items in the same way that the array::distinct() function is used.

LET $array = [1,1,3,4,4,4,4,4,4];

RETURN [
    $array.distinct(),
    <set>$array
];

Output
[
	[
		1,
		3,
		4
	],
	[
		1,
		3,
		4
	]
]

For all other behaviour and uses of a set, please see the page on arrays.