Difference

Difference( source, diff, ... )
Difference( source, diff, ... )
Difference( source, diff, ... )
Difference( source, diff, ... )
difference( source, diff, ... )
Difference( source, diff, ... )

Description

The Difference function compares the source, which can be an Array or Set, with the item(s) provided by diff, and returns all of the items that exist in source that do not exist in diff.

The run time of Difference is dependent on the size of the underlying set or page, and the exclusivity of the result. For large sets or pages with many non-exclusive items, executing Difference might result in a query timeout error.

To work around this, you may specify a larger query timeout via the driver that you are using.

Parameters

Argument Type Definition and Requirements

source

The source array or set to be compared. The type of source must match all of the items in diff.

diff

One or more difference array or setref objects. The type of all items in diff must match the type of source.

Returns

When source is an array, an array of the items in source that are missing from diff.

When source is a setref, a setref object of the items in source that are missing from diff.

Examples

The following query takes the source SetRef (i.e. set reference) which is created by locating the search term "fire" in the index named "spells_by_element" and removing all difference SetRef which was created by locating the search term "water" in the Index named "spells_by_element". The Paginate function materialized the results of the Difference operation in an array of type Page.

client.Query(
    Paginate(
        Difference(
            Match(Index("spells_by_element"), "fire"),
            Match(Index("spells_by_element"), "water")
        )
    )
);
ObjectV(data: Arr(RefV(id = "181388642046968320", collection = RefV(id = "spells", collection = RefV(id = "collections")))))
result, err := client.Query(
	f.Paginate(
		f.Difference(
			f.MatchTerm(f.Index("spells_by_element"), "fire"),
			f.MatchTerm(f.Index("spells_by_element"), "water"))))

if err != nil {
	fmt.Fprintln(os.Stderr, err)
} else {
	fmt.Println(result)
}
map[data:[{181388642046968320 0xc000142270 0xc000142270 <nil>}]]
System.out.println(
    client.query(
        Paginate(
            Difference(
                Match(Index(Value("spells_by_element")), Value("fire")),
                Match(Index(Value("spells_by_element")), Value("water"))
            )
        )
    ).get());
{data: [ref(id = "181388642046968320", collection = ref(id = "spells", collection = ref(id = "collections")))]}
client.query(
  q.Paginate(
    q.Difference(
      q.Match(q.Index('spells_by_element'), 'fire'),
      q.Match(q.Index('spells_by_element'), 'water'),
    )
  )
)
.then((ret) => console.log(ret))
.catch((err) => console.error('Error: %s', err))
{ data: [ Ref(Collection("spells"), "181388642046968320") ] }
result = client.query(
  q.paginate(
    q.difference(
      q.match(q.index("spells_by_element"), "fire"),
      q.match(q.index("spells_by_element"), "water")
    )
  )
)
print(result)
{'data': [Ref(id=181388642046968320, collection=Ref(id=spells, collection=Ref(id=collections)))]}
client.query(
  Paginate(
    Difference(
      Match(Index("spells_by_element"), "fire"),
      Match(Index("spells_by_element"), "water"))))
{data: [ref(id = "181388642046968320", collection = ref(id = "spells", collection = ref(id = "collections")))]}

The following query is similar to the example above, but it returns document events instead of the index tuples.

client.Query(
    Paginate(
        Difference(
            Match(Index("spells_by_element"), "fire"),
            Match(Index("spells_by_element"), "water")
        ),
        events: true
    )
);
ObjectV(data: Arr(ObjectV(ts: LongV(1603756252570000),action: StringV(add),document: RefV(id = "181388642046968320", collection = RefV(id = "spells", collection = RefV(id = "collections")))), ObjectV(ts: LongV(1603756252570000),action: StringV(add),document: RefV(id = "181388642071085568", collection = RefV(id = "spells", collection = RefV(id = "collections")))), ObjectV(ts: LongV(1603756252570000),action: StringV(remove),document: RefV(id = "181388642071085568", collection = RefV(id = "spells", collection = RefV(id = "collections"))))))
result, err := client.Query(
	f.Paginate(
		f.Events(
			f.Difference(
				f.MatchTerm(f.Index("spells_by_element"), "fire"),
				f.MatchTerm(f.Index("spells_by_element"), "water")))))

if err != nil {
	fmt.Fprintln(os.Stderr, err)
} else {
	fmt.Println(result)
}
map[data:[map[action:add document:{181388642046968320 0xc0000b1530 0xc0000b1530 <nil>} ts:1603747155400000] map[action:add document:{181388642071085568 0xc0000b1710 0xc0000b1710 <nil>} ts:1603747155400000] map[action:remove document:{181388642071085568 0xc000160090 0xc000160090 <nil>} ts:1603747155400000]]]
System.out.println(
    client.query(
        Paginate(
            Events(
                Difference(
                    Match(Index(Value("spells_by_element")), Value("fire")),
                    Match(Index(Value("spells_by_element")), Value("water"))
                )
            )
        )
    ).get());
{data: [{ts: 1594315458560000, action: "add", document: ref(id = "181388642046968320", collection = ref(id = "spells", collection = ref(id = "collections")))}, {ts: 1594315458560000, action: "add", document: ref(id = "181388642071085568", collection = ref(id = "spells", collection = ref(id = "collections")))}, {ts: 1594315458560000, action: "remove", document: ref(id = "181388642071085568", collection = ref(id = "spells", collection = ref(id = "collections")))}]}
client.query(
  q.Paginate(
    q.Events(
      q.Difference(
        q.Match(q.Index('spells_by_element'), 'fire'),
        q.Match(q.Index('spells_by_element'), 'water'),
      )
    )
  )
)
.then((ret) => console.log(ret))
.catch((err) => console.error('Error: %s', err))
{
  data: [
    {
      ts: 1592269416750000,
      action: 'add',
      document: Ref(Collection("spells"), "181388642046968320")
    },
    {
      ts: 1592269416750000,
      action: 'add',
      document: Ref(Collection("spells"), "181388642071085568")
    },
    {
      ts: 1592269416750000,
      action: 'remove',
      document: Ref(Collection("spells"), "181388642071085568")
    }
  ]
}
result = client.query(
  q.paginate(
    q.difference(
      q.match(q.index("spells_by_element"), "fire"),
      q.match(q.index("spells_by_element"), "water")
    ),
    events=True
  )
)
print(result)
{'data': [{'ts': 1592859673180000, 'action': 'add', 'document': Ref(id=181388642046968320, collection=Ref(id=spells, collection=Ref(id=collections)))}, {'ts': 1592859673180000, 'action': 'add', 'document': Ref(id=181388642071085568, collection=Ref(id=spells, collection=Ref(id=collections)))}, {'ts': 1592859673180000, 'action': 'remove', 'document': Ref(id=181388642071085568, collection=Ref(id=spells, collection=Ref(id=collections)))}]}
client.query(
  Paginate(
    Difference(
      Match(Index("spells_by_element"), "fire"),
      Match(Index("spells_by_element"), "water")),
    events = true))
{data: [{ts: 1594667380890000, action: "add", document: ref(id = "181388642046968320", collection = ref(id = "spells", collection = ref(id = "collections")))}, {ts: 1594667380890000, action: "add", document: ref(id = "181388642071085568", collection = ref(id = "spells", collection = ref(id = "collections")))}, {ts: 1594667380890000, action: "remove", document: ref(id = "181388642071085568", collection = ref(id = "spells", collection = ref(id = "collections")))}]}

The following query demonstrates how various arrays are compared:

Value result = await client.Query(
    Arr(
        Difference(Arr("A", "B", "C"), Arr("B", "C", "D")),
        Difference(Arr("B", "C", "D"), Arr("A", "B", "C")),
        Difference(Arr("A", "B", "C"), Arr("C", "B", "A"))
    )
);
Arr(Arr(StringV(A)), Arr(StringV(D)), Arr())
result, err := client.Query(
	f.Arr{
		f.Difference(f.Arr{"A", "B", "C"}, f.Arr{"B", "C", "D"}),
		f.Difference(f.Arr{"B", "C", "D"}, f.Arr{"A", "B", "C"}),
		f.Difference(f.Arr{"A", "B", "C"}, f.Arr{"C", "B", "A"}),
	})

if err != nil {
	fmt.Fprintln(os.Stderr, err)
} else {
	fmt.Println(result)
}
[[A] [D] []]
System.out.println(
    client.query(
        Arr(
            Difference(
                Arr(Value("A"), Value("B"), Value("C")),
                Arr(Value("B"), Value("C"), Value("D"))
            ),
            Difference(
                Arr(Value("B"), Value("C"), Value("D")),
                Arr(Value("A"), Value("B"), Value("C"))
            ),
            Difference(
                Arr(Value("A"), Value("B"), Value("C")),
                Arr(Value("C"), Value("B"), Value("A"))
            )
        )
    ).get());
[["A"], ["D"], []]
client.query([
  q.Difference(['A', 'B', 'C'], ['B', 'C', 'D']),
  q.Difference(['B', 'C', 'D'], ['A', 'B', 'C']),
  q.Difference(['A', 'B', 'C'], ['C', 'B', 'A']),
])
.then((ret) => console.log(ret))
.catch((err) => console.error('Error: %s', err))
[ [ 'A' ], [ 'D' ], [] ]
result = client.query(
  [
    q.difference(['A', 'B', 'C'], ['B', 'C', 'D']),
    q.difference(['B', 'C', 'D'], ['A', 'B', 'C']),
    q.difference(['A', 'B', 'C'], ['C', 'B', 'A']),
  ]
)
print(result)
[['A'], ['D'], []]
println(Await.result(
  client.query(
    Arr(
      Difference(Arr("A", "B", "C"), Arr("B", "C", "D")),
      Difference(Arr("B", "C", "D"), Arr("A", "B", "C")),
      Difference(Arr("A", "B", "C"), Arr("C", "B", "A"))
    )
  ),
  5.seconds
))
[["A"], ["D"], []]

Was this article helpful?

We're sorry to hear that.
Tell us how we can improve!
Visit Fauna's Discourse forums or email docs@fauna.com

Thank you for your feedback!