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Data types

Since Memgraph is a graph database management system, data is stored in the form of graph elements: nodes and relationships. Each graph element can contain various types of data. This page describes which data types are supported in Memgraph.

Node labels & relationship types

Nodes can have labels that are used to label or group nodes. A label is of the type String, and each node can have none or multiple labels. Labels can be changed at any time.

Relationships have a type, also represented in the form of a String. Unlike nodes, relationships must have exactly one relationship type and once it is set upon creation, it can never be modified again.

Property types

Nodes and relationships can store various properties. Properties are similar to mappings or tables containing property names and their accompanying values. Property names are represented as text, while values can be of different types.

Each property can store a single value, and it is not possible to have multiple properties with the same name on a single graph element. But, the same property names can be found across multiple graph elements.

Also, there are no restrictions on the number of properties that can be stored in a single graph element. The only restriction is that the values must be of the supported types. Below is a table of supported data types.

TypeDescription
NullProperty has no value, which is the same as if the property doesn't exist.
StringA character string (text).
BooleanA boolean value, either true or false.
IntegerAn integer number.
FloatA floating-point number (real number).
ListA list containing any number of property values of any supported type under a single property name.
MapA mapping of string keys to values of any supported type.
DurationA period of time.
DateA date with year, month, and day.
LocalTimeTime without the time zone.
LocalDateTimeDate and time without the time zone.
note

If you want to modify List and Map property values, you need to replace them entirely.

The following queries are valid:

CREATE (:Node {property: [1, 2, 3]});
CREATE (:Node {property: {key: "value"}});

But these are not:

MATCH (n:Node) SET n.property[0] = 0;
MATCH (n:Node) SET n.property.key = "other value";

Temporal types

Duration

You can create a property of temporal type Duration from a string or a map by calling the function duration.

For strings, the duration format is: P[nD]T[nH][nM][nS] where n stands for a number, and the capital letters are used as a separator with each field in [] marked optional. For strings, Memgraph only allows the last field to be a double, e.g., P2DT2.5H. However, for maps, every field can be a double, an int or a mixture of both. Memgraph also supports negative durations.

namedescription
DDays
HHours
MMinutes
SSeconds

Example:

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

Maps can contain the following six fields: day, hour, minute, second, millisecond and microsecond.

Example:

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

At this point, it must be pointed out that durations internally hold microseconds. Each of the fields specified above is first converted to microseconds and then reduced by addition to a single value. This has an interesting use case:

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

This converts minutes, seconds to microseconds and effectively produces the following equation: minutes - seconds - microseconds.

Each of the individual fields of a duration can be accessed through its properties as follows:

namedescription
dayConverts all the microseconds back to days and returns the value.
hourSubtracts days and returns the leftover value as hours.
minuteSubtracts the days and returns the leftover value as minutes.
secondSubtracts the days and returns the leftover value as seconds.
millisecondSubtracts the days and returns the leftover value as milliseconds.
microsecondSubtracts the days and returns the leftover value as microseconds.
nanosecondSubtracts the days and returns the leftover value as nanoseconds.

Example:

CREATE (:F1Laps {lap: duration({day:1, hour: 2, minute:3, second:4})});
MATCH (f:F1Laps) RETURN f.lap.day;
// Result
>> 1
MATCH (f:F1Laps) RETURN f.lap.hour;
// Result
>> 2
MATCH (f:F1Laps) RETURN f.lap.minute;
// Result
>> 123 // The value without days is 2 hours and 3 minutes, that is 123 minutes
MATCH (f:F1Laps) RETURN f.lap.second;
// Result
>> 7384 // The value without days is 2 hours, 3 minutes and 4 seconds, that is 7384 minutes

Date

You can create a property of temporal type Date from a string or map by calling the function Date. For strings, the date format is specified by the ISO 8601: YYYY-MM-DD or YYYYMMDD or YYYY-MM.

namedescription
YYear
MMonth
DDay

The smallest year is 0 and the highest is 9999.

You can call date without arguments. This effectively sets the date field to the current date of the calendar (UTC clock).

Example:

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

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

Example:

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

You can access the individual fields of a date through its properties:

namedescription
yearReturns the year field
monthReturns the month field
dayReturns the day field

Example:

MATCH (b:Person) RETURN b.birthday.year;

LocalTime

You can create a property of temporal type LocalTime from a string or map 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.

namedescription
hHours
mMinutes
sSeconds

seconds can be defined as decimal fractions with up to 6 digits. The first 3 digits represent milliseconds, and the last 3 digits microseconds. For example, the string T22:10:32.300600 specifies 300 milliseconds and 600 microseconds.

You can call localTime without arguments. This effectively sets the time field to the current time of the calendar (UTC clock).

Example:

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

For maps, there are 5 fields available: hour, minute, second, millisecond and microsecond.

Example:

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

You can access the individual fields of a LocalTime through its properties:

namedescription
hourReturns the hour field
minuteReturns the minute field
secondReturns the second field
millisecondReturns the millisecond field
microsecondReturns the microsecond field

Example:

MATCH (s:School) RETURN s.Calculus.hour;

LocalDateTime

You can create a property of temporal type LocalDateTime from a string or map 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.

namedescription
YYear
MMonth
DDay
hHours
mMinutes
sSeconds

You can call localDateTime without arguments. This effectively sets the date and time fields to the current date and time of the calendar (UTC clock). 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)});

You can access the individual fields of LocalDateTime through its properties:

namedescription
yearReturns the year field
monthReturns the month field
dayReturns the day field
hourReturns the hour field
minuteReturns the minute field
secondReturns the second field
millisecondReturns the millisecond field
microsecondReturns the microsecond field

Example:

MATCH (f:Flights) RETURN f.AIR123.year;

Temporal types arithmetic

Temporal types Duration, Date, LocalTime and LocalDateTime support native arithmetic, and the operations are summarized in the following table:

Duration operations:

opresult
Duration + DurationDuration
Duration - DurationDuration
- DurationDuration

Date operations:

opresult
Date + DurationDate
Duration + DateDate
Date - DurationDate
Date - DateDuration

LocalTime operations:

opresult
LocalTime + DurationLocalTime
Duration + LocalTimeLocalTime
LocalTime - DurationLocalTime
LocalTime - LocalTimeDuration

LocalDateTime operations:

operationresult
LocalDateTime + DurationLocalDateTime
Duration + LocalTateTimeLocalDateTime
LocalDateTime - DurationLocalDateTime
LocalDateTime - LocalDateTimeDuration

Procedures API

Data types are also used within query modules. Check out the documentation for the Python API and C API.