Property is a component of schema that describes the data dimension of entities and relations in the graph. For example, node schema @card (Bank Card) has card number, balance, opening time and other node properties; edge schema @transaction (Transaction) has amount, transfer time and other edge properties.

Node properties _id, _uuid and edge properties _uuid, _from, _to, _from_uuid, _to_uuid are created automatically along with node schema and edge schema. These system properties are not deletable. Each schema may contain multiple properties.

Property features:

• Supported data types of property are: int32, int64, uint32, uint64, float, double, string, datetime, timestamp;
• and its corresponding arrays: []int32, []int64, []uint32, []uint64, []float, []double, []string, []datetime, []timestamp (under development);
• A property name can be shared between different schemas, but not within a schema;
• Please refer to chapter Basic Concepts for the naming conventions of property;
• Property is usually combined with schema in the form of @<schema>.<property>, interpreted as “the value of property <property> of nodes/edges of schema <schema>"; independent property expression without schema <property> indicates the value of property <property> for nodes or edges of any schema, or empty value if the property does not exist.

The difference between datetime and timestamp is: The data formats of datetime include yyyy-mm-dd hh:mm:ss and yyyy-mm-dd hh:mm:ss.ssssss; the string will be converted and stored as an uint64 that equals the number of milliseconds from 1900-01-01 00:00:00 UTC onwards. The timestamp calls for a string in the format yyyy-mm-dd hh:mm:ss and stores the represented value as an uint32 that equals the number of seconds from 1970-01-01 00:00:00 UTC onwards.

Integer type int32 is used by default if only writes int. String type string supports a maximum of 65,535 bytes. Decimal type float has 4 bytes with a data precision of 6 significant digits; double has 8 bytes with a data precision of 15 significant digits. Choose the appropriate decimal type based on the practical usage and amount of the data, as well as the size of the disk.

 V4.1  Use array index to refer to one or more elements in an array. The index starts from 0 and supported formats include: [n] (the element with index 0)、[n1:n2] (an array formed by elements from index n1 to n2)、[:n] (an array formed by elements from index 0 to n)、[n:] (an array formed by elements from index n to the last).

Show Property

Returned table name: _nodeProperty and/or _edgeProperty
Returned table header: name | type | lte | schema | description (the name, data type, whether LTEed, schema and description of the property)

Syntax:

// To show properties of all schemas in the current graphset (node properties and edges properties in separated tables)
show().property()

// To show properties of all node schemas in the current graphset
show().node_property()

// To show properties of all edge schemas in the current graphset
show().edge_property()

// To show properties of a certain node schema in the current graphset
show().node_property(@<schema>)

// To show properties of a certain edge schema in the current graphset
show().edge_property(@<schema>)

Create Property

string is used by default if data type is ignored when creating property.

Syntax:

// To create a node property under a certain node schema in the current graphset
create().node_property(@<schema>, "<name>", <type?>, "<desc?>")

// To create a node property under all node schemas in the current graphset
create().node_property(@*, "<name>", <type?>, "<desc?>")

// To create an edge property under a certain edge schema in the current graphset
create().edge_property(@<schema>, "<name>", <type?>, "<desc?>")

// To create an edge property under all edge schemas in the current graphset
create().edge_property(@*, "<name>", <type?>, "<desc?>")

// To create multiple node/edge properties by using the four methods above
create()
  .node_property(@<schema>, "<name>", <type?>, "<desc?>")
  .node_property(@*, "<name>", <type?>, "<desc?>")
  .edge_property(@<schema>, "<name>", <type?>, "<desc?>")
  .edge_property(@*, "<name>", <type?>, "<desc?>")

Example: Using one UQL to create node properties "card balance" and "level" under @card and edge property "time" for all edge schemas

create().node_property(@card, "sum," double, "card balance")
  .node_property(@card, "level", int, "card level")
  .edge_property(@*, "time", datetime)

Example: Using one UQL to create edge properties "transaction number", "time" and "amount" under @transaction

create().edge_property(@transaction, "no", "", "transaction number")
  .edge_property(@transaction, "time", datetime)
  .edge_property(@transaction, "amount", double)

Example: Using one UQL to create node properties "card balance", "level" under @card and edge properties "transaction number", "time" and "amount" under @transaction

create().node_property(@card, "sum", double, "card balance")
  .node_property(@card, "level", int, "card level")
  .edge_property(@transaction, "no", "", "transaction number")
  .edge_property(@transaction, "time", datetime)
  .edge_property(@transaction, "amount", double)

Alter Property (Name, Description)

Syntax:

// To modify the name, description of a certain node property under a certain node schema in the current graphset
alter().node_property(@<schema>.<property>)
  .set({name: "<new_name?>", description: "<new_desc?>"})

// To modify the name, description of a certain node property (if has) under all node schemas in the current graphset
alter().node_property(@*.<property>)
  .set({name: "<new_name?>", description: "<new_desc?>"})

// To modify the name, description of a certain edge property under a certain edge schema in the current graphset
alter().edge_property(@<schema>.<property>)
  .set({name: "<new_name?>", description: "<new_desc?>"})

// To modify the name, description of a certain edge property (if has) under all edge schemas in the current graphset
alter().edge_property(@*.<property>)
  .set({name: "<new_name?>", description: "<new_desc?>"})

Example: Rename @card property "sum" as "balance"

alter().node_property(@card.sum)
  .set({name: "balance"})

Example: Rename property "time" as "createTime" for all edges

alter().edge_property(@*.time)
  .set({name: "createTime"})

Drop Property

User may delete properties that are no longer needed to save disk space. Deleting property operation can be executed in real time, and there will not be a considerable wait time. Once executed, the property is deleted immediately.

Except for system properties _id, _uuid, _from, _to, _from_uuid and _to_uuid which are not allowed to be deleted, all the other properties of schema can be deleted.

Syntax:

// To delete a certain node property under a certain node schema from the current graphset
drop().node_property(@<schema>.<property>)

// To delete a certain node property (if has) under all node schemas from the current graphset
drop().node_property(@*.<property>)

// To delete a certain edge property under a certain edge schema from the current graphset
drop().edge_property(@<schema>.<property>)

// To delete a certain edge property (if has) under all edge schemas from the current graphset
drop().edge_property(@*.<property>)

// To delete multiple node/edge properties by using the four methods above
drop()
  .node_property(@<schema>.<property>)
  .node_property(@*.<property>)
  .edge_property(@<schema>.<property>)
  .edge_property(@*.<property>)

Example: Delete node property "branch" under @card and edge property "time" for all edges

drop().node_property(@card.branch).edge_property(@*.time)

Example: Delete @default edge property "test"

drop().edge_property(@default.test)