What Types of Data Are Supported in Memgraph?

Memgraph is a powerful graph database that stores data in the form of graph objects—nodes and relationships. Both nodes and relationships can hold different properties with a variety of data types. In this blog post, I’ll share different data types supported by Memgraph and how to use them.

Node Labels and Relationship Data Types

• Nodes. In Memgraph, nodes can have labels that help to group and categorize the dataset. Labels are strings and each node can have multiple labels or none at all. What’s important is that labels can be modified at any time, allowing for flexible data organization.

For example, here's how to create a node with the Person label.

CREATE {p:Person {name: ‘Alice’, age: 27}}

• Relationships. Unlike nodes, relationships must have exactly one type represented as a string. You cannot change the type of a relationship once you set it during creation.

For example, here's how to create two nodes, Alice and Bob, with a :CONNECTED_TO relationship between them.

CREATE (a:Person {name: 'Alice'}), (b:Person {name: 'Bob'}), (a)-[:CONNECTED_TO]-(b)

Property Data Types

Nodes and relationships in Memgraph store various properties, similar to key-value pairs found in maps. Property names are represented as text, while their values can be of several different types. Each property can store only one value and cannot have duplicate names within the same graph element. However, you can use the same property names across different graph elements. There are no restrictions on the number of properties a single graph element can have, as long as the values are of supported types.

Here is a table of supported property types in Memgraph.

Maps in Cypher Query Language

Literal Maps

You can explicitly construct literal maps using key-value pairs in Cypher. Read more about Literal Maps in docs.

RETURN {key: 'Value', listKey: [{inner: 'Map1'}, {inner: 'Map2'}]}

Map Projection

Map projection syntax allows constructs maps from nodes, relationships, other map values, and values with properties. A map projection starts with a variable bound to a graph entity and includes a body of comma-separated map elements enclosed in curly braces.

map_variable {map_element, [, ...n]}

Temporal Types

Memgraph supports several temporal types, each with specific creation and manipulation rules:

• Duration
• Date
• LocalTime
• LocalDateTime
• ZonedDateTime

Duration

Create durations from strings or maps, storing values in microseconds by calling the function duration(). Read more about Duration in docs.

For strings, the duration format is: P[nD]T[nH][nM][nS]

Example:

CREATE (:F1Laps {lap: duration("PT2M2.33S")});

Maps can contain the following six fields: day, hour, minute, second, millisecond, and microsecond. Every field can be a double, an int or a mixture of both. Memgraph also supports negative durations.

Example:

CREATE (:F1Laps {lap: duration({minute:2, second:2, microsecond:33})});

Date

Create dates from strings or maps by calling the function date().

For strings, the date format is specified by the ISO 8601: YYYY-MM-DD or YYYYMMDD or YYYY-MM.

Example:

CREATE (:Person {birthday: date("1947-07-30")});

For maps, three fields are available: year, month and day

Example:

CREATE (:Person {birthday: date({year:1947, month:7, day:30})});

LocalTime

LocalTime values can be created from strings or maps by calling the function localTime().

For strings, the local time format is specified by the ISO 8601: [T]hh:mm:ss or [T]hh:mm or [T]hhmmss or [T]hhmm or [T]hh.

Example:

CREATE (:School {Calculus: localTime("09:15:00")});

For maps, five fields are available: hour, minute, second, millisecond and microsecond.

Example:

CREATE (:School {Calculus: localTime({hour:9, minute:15})});

LocalDateTime

LocalDateTime values can be created similarly by calling the function localDateTime().

For strings, the local time format is specified by the ISO 8601: YYYY-MM-DDThh:mm:ss or YYYY-MM-DDThh:mm or YYYYMMDDThhmmss or YYYYMMDDThhmm or YYYYMMDDThh.

Example:

CREATE (:Flights {AIR123: localDateTime("2021-10-05T14:15:00")});

For maps the following fields are available: year, month, day, hour, minute, second, millisecond and microsecond.

Example:

CREATE (:Flights {AIR123: localDateTime({year:2021, month:10, day:5, hour:14, minute:15})});

ZonedDateTime

ZonedDateTime values can also be created from strings or maps, with timezone information by calling the datetime() function.

The datetime() function takes strings that follow the ISO 8601 standard. An ISO 8601-compliant string that stands for a zoned datetime value has two parts: <DateTime><timezone>.

The first part is defined the same way as LocalDateTime, and the second part follows one of the given timezone formats:

• Z
• ±hh:mm
• ±hh:mm[ZoneName]
• ±hhmm
• ±hhmm[ZoneName]
• ±hh
• ±hh[ZoneName]
• [ZoneName], where ZoneName is a timezone name from the IANA timezone database

Example:

CREATE (:Flight {AIR123: datetime("2024-04-21T14:15:00-07:00[America/Los_Angeles]")});
CREATE (:Flight {AIR123: datetime("2021-04-21T14:15:00Z")});

Maps for constructing ZonedDateTime values may have the following fields: year, month, day, hour, minute, second, millisecond, microsecond and timezone.

There are two options for the timezone field:

• string: timezone name from the IANA timezone database
• int: offset from UTC (in minutes)

Example:

CREATE (:Flight {AIR123: datetime({year: 2024, month: 4, day: 21, hour: 14, minute: 15, timezone: "America/Los_Angeles"})});
CREATE (:Flight {AIR123: datetime({year: 2021, month: 4, day: 21, hour: 14, minute: 15, timezone: -60})});

Enum

Enums need to be defied before they can be used. They represent a set od predefined values. For example:

CREATE ENUM Status VALUES { Good, Okay, Bad };

To see existing enums:

SHOW ENUMS;

Enums can also be referenced using their literal form in queries:

CREATE (:Machine {status: Status::Good});
CREATE (:Machine {status: Status::Okay});
MATCH (n:Machine) WHERE n.status = Status::Bad RETURN n;

The ToEnum() function takes string(s) to lookup and return enum values.

RETURN ToEnum("Status", "Good");
RETURN ToEnum("Status::Okay");

Conclusion

Memgraph offers a versatile set of data types that cater to a wide range of data storage and query needs. By understanding and using those data types, you can build efficient and powerful graph-based applications. Whether you’re working with simple text and numbers of complex temporal data and enumerations, Memgraph’s data types provide the flexibility you need to manage your data effectively.

Further Reading

• Data Structures Cheat Sheet
• Using Schema Functions to Model Your Data in Memgraph
• The Complete Cypher Cheat Sheet