[FEATURE]: Unique Constraint in DQL

[jdgamble555]

Have you tried Dgraph before this proposal? and did not find anything similar?

No response

What you wanted to do.

From the DQL level up, there should be a way to force uniqueness. For backwards compatibility this should be easy. Adding this to a node that already has duplicate values would not be allowed.

This simplest way todo this would be to have a @unique directive in the dql schema:

type Film {
  name @unique 
  release_date
  revenue
  running_time
  starring
  director
}

or with a composite index:

type Film @unique(name, release_date)  {
  name
  release_date
  revenue
  running_time
  starring
  director
}

---

This should also be possible on a 'facet', but there would need to be a way to declare facet types in dql. Perhaps:

facet Friend {
  close @unique
  ...

and for composite:

facet Friend @unique(close, date) {
  close
  date
}

Note: In GraphQL, the unique directive would need the "field" input to be not break the GraphQL spec, here we can simplify it with just an array inside ().

What you actually did.

You can create this in GraphQL, but it is not enforced once added, and DQL is certainly not enforced. Composite indexes are also currently impossible.

Why wasn't it great, with examples.

We need better data integrity.

Additional information.

It should be 100% impossible to add any kind of duplicate data once this unique directive is activated.

Unique constraints should be nullable by default, but could be not null with the @NotNull directive.

This is how @akon-dey wants to implement this. First in DQL, then GraphQL.

Related to:

• GraphQL Composite Uniques
• DQL Non Null Constraints
• Check Constraints

[rderbier]

partially addressed in JIRA https://dgraph.atlassian.net/browse/DGRAPHCORE-206 sprint 5

[rderbier]

replaced by #8865 which is linked to the JIRA covering this new feature