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‎modules/ROOT/pages/schema/graph-types/alter-graph-types.adoc‎

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@@ -93,8 +93,8 @@ So long as the identifying node labels or relationship types are the same as tho
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For more information about how graph types are implemented, see xref:schema/graph-types/set-graph-types.adoc#graph-type-implementation[Set a graph type -> Graph type implementation: translation to constraints].
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[[limitations]]
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== Limitations
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[[rules]]
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== Rules
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The behavior of key and property uniqueness constraints on identifying node labels and relationship types, as well as constraints on non-identifying node labels and relationship types with regard to the `ALTER CURRENT GRAPH TYPE ALTER` command follows that of xref:schema/constraints/index.adoc[Neo4j constraints]; they can be created and dropped, but they cannot be altered through a single command (they must, in that case, be dropped and recreated to fit the desired alteration).
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‎modules/ROOT/pages/schema/graph-types/drop-graph-type-elements.adoc‎

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:page-role: cypher-25-only new-neo4j-2025.xx enterprise-edition
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= Drop elements in a graph type
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The `ALTER CURRENT GRAPH TYPE DROP` command allows you to drop elements from a graph type.
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[NOTE]
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Dropping elements from a graph type the link:{neo4j-docs-base-uri}/operations-manual/current/authentication-authorization/database-administration/#access-control-database-administration-constraints[`DROP CONSTRAINT` privilege].
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.Set graph type
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[source, cypher]
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----
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ALTER CURRENT GRAPH TYPE SET {
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(p:Person => :Resident {name :: STRING, ssn :: INTEGER})
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REQUIRE (p.name, p.ssn) IS KEY,
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(:Pet => :Resident&Animal {insuranceNumber :: INTEGER IS KEY, healthCertificate :: STRING IS UNIQUE, name :: STRING}),
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(:Robot => :Resident&Machine {application :: STRING NOT NULL, id :: INTEGER NOT NULL}),
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(:City => {name :: STRING NOT NULL, population :: INTEGER}),
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(:Resident)-[:LIVES_IN => {since:: ANY NOT NULL}]->(:City),
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CONSTRAINT company_name FOR (c:Company) REQUIRE c.name IS KEY,
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CONSTRAINT resident_address FOR (resident:Resident) REQUIRE resident.address :: STRING,
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CONSTRAINT ownership_id FOR ()-[owner:OWNER_OF]->() REQUIRE owner.ownershipId IS UNIQUE,
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(:Company => {name :: STRING, address :: STRING IS UNIQUE}),
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(:Person)-[:WORKS_FOR => {role :: STRING})->(:Company)
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}
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----
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[[drop-element-types]]
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== Drop node and relationship element types
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To fully drop a node or relationship element type, it is only necessary to define its identifying node label/relationship type appended with `\=>`.
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.Drop node and relationship element types
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[source, cypher]
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----
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ALTER CURRENT GRAPH TYPE DROP {
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(:Pet => ),
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()-[:LIVES_IN => ]->()
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}
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----
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You can also define the full element type when dropping an element type.
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Partial definitions, however, are not allowed.
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[cols="3*", options="header"]
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|===
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| Allowed -- identifying node label/relationship type only
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| Allowed -- full definition
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| Not allowed -- partial definition
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a|
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[source]
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----
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ALTER CURRENT GRAPH TYPE DROP {
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(:Pet => )
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}
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----
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a|
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[source]
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----
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ALTER CURRENT GRAPH TYPE DROP {
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(:Pet => :Resident&Animal {insuranceNumber :: INTEGER IS KEY, healthCertificate :: STRING IS UNIQUE, name :: STRING})
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}
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----
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a|
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[source]
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----
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ALTER CURRENT GRAPH TYPE DROP {
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(:Pet => :Resident&Animal)
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}
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----
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|===
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Dropping a node or relationship element type in this way can remove the following constraints:
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* Node label existence constraints
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* Source and target node label constraints
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* Property type and property existence constraints defined against a node or relationship element type.
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These constraints cannot be removed separately from the node or relationship element type they support.
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Not allowed -- drop a dependent constraint from a node or relationship element type
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[source, cypher, role=test-fail]
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----
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ALTER CURRENT GRAPH TYPE DROP {
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CONSTRAINT constraint_22a8753a // <1>
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}
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----
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<1> `constraint_22a8753a` is a property existence constraint defined on the `City` node element type (constraint names are returned by the xref:schema/graph-types/list-graph-types.adoc#graph-type-elements-in-show-constraints[`SHOW CONSTRAINTS`] command).
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*Removing a node or relationship element type does not, however, remove any property uniqueness or key constraints defined against a node or relationship element type.*
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*Rather, it leaves them as constraints on non-identifying node-labels and relationship types.*
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*These must therefore be removed separately, using their constraint name.*
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For more information, see xref:schema/graph-types/drop-graph-type-elements.adoc#drop-constraints-on-identifying-and-non-identifying-labels-and-types[Drop constraints on identifying and non-identifying node labels and relationship types] below.
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If the identifying label of a node element type is also constrained as a source/target node label in a relationship element type, then the node element type cannot be dropped without also dropping or first altering the relationship element type.
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.Not allowed -- drop a node element type whose identifying label is also the source/target node label in a relationship element type
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[source, cypher, role=test-fail]
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----
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ALTER CURRENT GRAPH TYPE DROP {
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(:Person => )
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}
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----
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.Error message
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[source, error]
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----
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22NCE: data exception - node element type in use. The node element type identified by the label `Person` is referenced in the graph type element '()-[:`WORKS_FOR` =>]->()' and cannot be dropped.
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----
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[[drop-constraints-on-identifying-and-non-identifying-labels-and-types]]
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== Drop constraints on identifying and non-identifying node labels and relationship types
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== Drop constraints on identifying and non-identifying node labels and relationship types
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Key and property uniqueness constraints can only be dropped by using the `CONSTRAINT [name]` syntax in the `ALTER CURRENT GRAPH TYPE DROP` command, regardless if they were defined on an identifying or non-identifying label.
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Property existence and property type constraints defined on non-identifying node labels and relationship types are also dropped in this way.
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The names of constraints are returned by the xref:schema/constraints/list-constraints.adoc[`SHOW CONSTRAINTS`] command.
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.Drop explicitly named and generated name key and property uniqueness constraint
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[source, cypher]
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----
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ALTER CURRENT GRAPH TYPE DROP {
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CONSTRAINT ownership_id,
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CONSTRAINT constraint_302a3693
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}
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----
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These constraints can also be dropped from the graph type using the xref:schema/constraints/drop-constraints.adoc[`DROP CONSTRAINT`] command.
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.Drop property type constraint on a non-identifying node label
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[source, cypher]
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----
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DROP CONSTRAINT resident_address
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----
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[[drop-full-graph-type]]
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== Drop a full graph type
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To drop a full graph type, use the `ALTER CURRENT GRAPH TYPE SET` command.
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This will replace the existing graph type with a new (possibly empty) graph type.
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.Drop full graph type and replace it with an empty graph type
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[source, cypher]
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----
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ALTER CURRENT GRAPH TYPE SET { }
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----
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.Drop full graph type and replace with a new graph type
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[source, cypher]
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----
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ALTER CURRENT GRAPH TYPE SET {
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(n:Label => :LabelTwo {property :: STRING})
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}
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----

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