Unique constraint in DQL

jdgamble555 · March 24, 2023, 4:12am

I believe @gajanan would disagree with this statement, as he talked about hopefully adding a unique directive to the DQL layer.

github.com/dgraph-io/dgraph

[FEATURE]: Unique Constraint in DQL

opened 11:40PM - 02 Nov 22 UTC

closed 06:12PM - 09 Jun 23 UTC

jdgamble555

kind/feature area/querylang community

### Have you tried Dgraph before this proposal? and did not find anything simila…r? _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](https://dgraph.io/docs/query-language/schema/): ```graphql type Film { name @unique release_date revenue running_time starring director } ``` or with a composite index: ```graphql 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: ```graphql facet Friend { close @unique ... ``` and for composite: ```graphql 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](https://github.com/dgraph-io/dgraph/issues/8179) - [DQL Non Null Constraints](https://github.com/dgraph-io/dgraph/issues/8409) - [Check Constraints](https://github.com/dgraph-io/dgraph/issues/8410)

J

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Unique constraint in DQL

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