apoc.meta.relTypeProperties

This procedure is not considered safe to run from multiple threads. It is therefore not supported by the parallel runtime. For more information, see the Cypher Manual → Parallel runtime.

Details
Syntax	`apoc.meta.relTypeProperties([ config ]) :: (relType, sourceNodeLabels, targetNodeLabels, propertyName, propertyTypes, mandatory, propertyObservations, totalObservations)`
Description	Examines the full graph and returns a table of metadata with information about the `RELATIONSHIP` values therein.
Input arguments	Name	Type	Description
Input arguments	`config`	`MAP`	`{ includeLabels = [] :: LIST<STRING>, includeRels = [] :: LIST<STRING>, excludeLabels = [] :: LIST<STRING>, excludeRels = [] :: LIST<STRING>, sample = 1000 :: INTEGER, maxRels = 100 :: INTEGER }`. The default is: `{}`.
Return arguments	Name	Type	Description
	`relType`	`STRING`	The type of the relationship.
	`sourceNodeLabels`	`LIST<STRING>`	The labels belonging to the start node.
	`targetNodeLabels`	`LIST<STRING>`	The labels belonging to the end node.
	`propertyName`	`STRING`	The name of the property.
	`propertyTypes`	`LIST<STRING>`	The types this property has.
	`mandatory`	`BOOLEAN`	Whether or not this property exists on all nodes of the given type.
	`propertyObservations`	`INTEGER`	The number of times this property was observed.
	`totalObservations`	`INTEGER`	The number of times the label was seen.

Config parameters

This procedure supports the following config parameters:

Config parameters
Name	Type	Default	Description
`includeLabels`	`LIST<STRING>`	[]	Node labels to include. Default is to include all node labels.
`includeRels`	`LIST<STRING>`	[]	Relationship types to include. Default is to include all relationship types.
`excludeLabels`	`LIST<STRING>`	[]	Node labels to exclude. Default is to include all node labels.
`excludeRels`	`LIST<STRING>`	[]	Relationship types to exclude. Default is to include all relationship types.
`sample`	`INTEGER`	1000	Number of nodes to sample. Setting `sample` to `-1` will remove sampling.
`maxRels`	`INTEGER`	100	Number of relationships to read per sampled node.

Sampling

Specify the sample parameter (1000 by default) to analyze a subset of the data.

The sample, along with the count of nodes for each label, is used to calculate a skip value. Since this value is generated using a random number generator, results obtained through the sampling method may vary between subsequent runs.

Example 1. Calculating skip count for data sampling

If a database contains 500 nodes with the label Foo label, the skip count for that label is calculated as follows:

The skip count per node label is determined by generating a random number between (totalNodesForLabel / sample) ± 0.1.

Sample 10: skipCount = 500 / 10 = 50
The resulting skip count will be between 45 and 55.

Sample 50: skipCount = 500 / 50 = 10
The resulting skip count will be between 9 and 11.

Sample 100: skipCount = 500 / 100 = 5
The resulting skip count will be 5.

The skip count represents the number of nodes skipped before one is examined. For instance, with a skip count of 5, every 5th node is examined. Consequently, a higher sample number results in more nodes being sampled.

To stop sampling set sample: -1.

Deprecated parameters
Name	Type	Default	Description
`labels`	`LIST<STRING>`	[]	Deprecated, use `includeLabels`.
`rels`	`LIST<STRING>`	[]	Deprecated, use `includeRels`.
`excludes`	`LIST<STRING>`	[]	Deprecated, use `excludeLabels`.

Usage Examples

The examples in this section are based on the following sample graph:

CREATE (Keanu:Person {name:'Keanu Reeves', born:1964})
CREATE (TomH:Person {name:'Tom Hanks', born:1956})
CREATE (LillyW:Person {name:'Lilly Wachowski', born:1967})

CREATE (TheMatrix:Movie {title:'The Matrix', released:1999, tagline:'Welcome to the Real World'})
CREATE (TheMatrixReloaded:Movie {title:'The Matrix Reloaded', released:2003, tagline:'Free your mind'})
CREATE (TheMatrixRevolutions:Movie {title:'The Matrix Revolutions', released:2003, tagline:'Everything that has a beginning has an end'})
CREATE (SomethingsGottaGive:Movie {title:"Something's Gotta Give", released:2003})
CREATE (TheDevilsAdvocate:Movie {title:"The Devil's Advocate", released:1997, tagline:'Evil has its winning ways'})

CREATE (YouveGotMail:Movie {title:"You've Got Mail", released:1998, tagline:'At odds in life... in love on-line.'})
CREATE (SleeplessInSeattle:Movie {title:'Sleepless in Seattle', released:1993, tagline:'What if someone you never met, someone you never saw, someone you never knew was the only someone for you?'})
CREATE (ThatThingYouDo:Movie {title:'That Thing You Do', released:1996, tagline:'In every life there comes a time when that thing you dream becomes that thing you do'})
CREATE (CloudAtlas:Movie {title:'Cloud Atlas', released:2012, tagline:'Everything is connected'})

CREATE (Keanu)-[:ACTED_IN {roles:['Neo']}]->(TheMatrix)
CREATE (Keanu)-[:ACTED_IN {roles:['Neo']}]->(TheMatrixReloaded)
CREATE (Keanu)-[:ACTED_IN {roles:['Neo']}]->(TheMatrixRevolutions)
CREATE (Keanu)-[:ACTED_IN {roles:['Julian Mercer']}]->(SomethingsGottaGive)
CREATE (Keanu)-[:ACTED_IN {roles:['Kevin Lomax']}]->(TheDevilsAdvocate)

CREATE (TomH)-[:ACTED_IN {roles:['Joe Fox']}]->(YouveGotMail)
CREATE (TomH)-[:ACTED_IN {roles:['Sam Baldwin']}]->(SleeplessInSeattle)
CREATE (TomH)-[:ACTED_IN {roles:['Mr. White']}]->(ThatThingYouDo)
CREATE (TomH)-[:ACTED_IN {roles:['Zachry', 'Dr. Henry Goose', 'Isaac Sachs', 'Dermot Hoggins']}]->(CloudAtlas)

CREATE (LillyW)-[:DIRECTED]->(TheMatrix);

We can return the metadata of the database from a sample of the database contents, by running the following query:

CALL apoc.meta.relTypeProperties();

Results
relType	sourceNodeLabels	targetNodeLabels	propertyName	propertyTypes	mandatory	propertyObservations	totalObservations
":`ACTED_IN`"	["Person"]	["Movie"]	"roles"	["StringArray"]	FALSE	9	9
":`DIRECTED`"	["Person"]	["Movie"]	NULL	NULL	FALSE	0	1

We can return metadata for a subset of relationship types by specifying the rels config parameter. The following returns the metadata for the ACTED_IN label:

CALL apoc.meta.relTypeProperties({rels: ["ACTED_IN"]});

Results
relType	sourceNodeLabels	targetNodeLabels	propertyName	propertyTypes	mandatory	propertyObservations	totalObservations
":`ACTED_IN`"	["Person"]	["Movie"]	"roles"	["StringArray"]	FALSE	9	9

We can control the number of relationships sampled by specifying the maxRels parameter. The following returns metadata based on sampling up to 3 relationships per relationship type:

CALL apoc.meta.relTypeProperties({maxRels: 3});

Results
relType	sourceNodeLabels	targetNodeLabels	propertyName	propertyTypes	mandatory	propertyObservations	totalObservations
":`ACTED_IN`"	["Person"]	["Movie"]	"roles"	["StringArray"]	FALSE	3	9
":`DIRECTED`"	["Person"]	["Movie"]	NULL	NULL	FALSE	0	1