Delete Mutations in DQL

A delete mutation, identified by the delete keyword, removes triples from the store.

For example, if the store contained the following:

<0xf11168064b01135b> <name> "Lewis Carrol"
<0xf11168064b01135b> <died> "1998"
<0xf11168064b01135b> <dgraph.type> "Person" .

Then, the following delete mutation deletes the specified erroneous data, and removes it from any indexes:

{
  delete {
     <0xf11168064b01135b> <died> "1998" .
  }
}

Wildcard delete

In many cases you will need to delete multiple types of data for a predicate. For a particular node N, all data for predicate P (and all corresponding indexing) is removed with the pattern S P *.

{
  delete {
     <0xf11168064b01135b> <author.of> * .
  }
}

The pattern S * * deletes all the known edges out of a node, any reverse edges corresponding to the removed edges, and any indexing for the removed data.

Note For mutations that fit the S * * pattern, only predicates that are among the types associated with a given node (using dgraph.type) are deleted. Any predicates that don’t match one of the node’s types will remain after an S * * delete mutation.

{
  delete {
     <0xf11168064b01135b> * * .
  }
}

If the node S in the delete pattern S * * has only a few predicates with a type defined by dgraph.type, then only those triples with typed predicates are deleted. A node that contains untyped predicates will still exist after a S * * delete mutation.

Note The patterns * P O and * * O are not supported because it’s inefficient to store and find all the incoming edges.

Deletion of non-list predicates

Deleting the value of a non-list predicate (i.e a 1-to-1 relationship) can be done in two ways.

Using the wildcard delete (star notation) mentioned in the last section.
Setting the object to a specific value. If the value passed is not the current value, the mutation will succeed but will have no effect. If the value passed is the current value, the mutation will succeed and will delete the non-list predicate.

For language-tagged values, the following special syntax is supported:

{
  delete {
    <0x12345> <name@es> * .
  }
}

In this example, the value of the name field that is tagged with the language tag es is deleted. Other tagged values are left untouched.