apoc.meta.schema

Procedure APOC Core

apoc.meta.schema({config}) - examines a subset of the graph to provide a map-like meta information

Signature

apoc.meta.schema(config = {} :: MAP?) :: (value :: MAP?)

Input parameters

Name Type Default

config

MAP?

{}

Config parameters

The procedure support the following config parameters:

Table 1. Config parameters
name type default description

sample

Long

1000

number of nodes to sample per label. See "Sampling" section below.

Sampling

Because the count stores return an incomplete picture of the data, we have to cross check the results with the actual data to filter out false positives.

We use a subset of the data to analyze by specifying the sample parameter (1000 by default).

Through this parameter, for each label we split data for each node-label into batches of (total / sample) ± rand where total is the total number of nodes with that label and rand is a number between 0 and total / sample / 10.

So, we pick a percentage of nodes with that label of roughly sample / total * 100% to check against. We pick the first node of each batch, and we analyze the properties and the relationships.

Output parameters

Name Type

value

MAP?

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 (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 (s0:sameName{id:1}) -[r0:sameName {alfa: 'beta'}] -> (t0:sameName{id:2});
CALL apoc.meta.schema()
YIELD value
UNWIND keys(value) AS key
RETURN key, value[key] AS value;

Note that, in case of relationship type and node label with the same name, the relationships will be distinguished by the suffix " (RELATIONSHIP)"

Table 2. Results
key value

"Movie"

{count: 9, relationships: {ACTED_IN: {count: 41, properties: {roles: {existence: FALSE, type: "LIST", array: TRUE}}, direction: "in", labels: ["Person"]}}, type: "node", properties: {tagline: {existence: FALSE, type: "STRING", indexed: FALSE, unique: FALSE}, title: {existence: FALSE, type: "STRING", indexed: FALSE, unique: FALSE}, released: {existence: FALSE, type: "INTEGER", indexed: FALSE, unique: FALSE}}, labels: []}

"ACTED_IN"

{count: 9, type: "relationship", properties: {roles: {existence: FALSE, type: "LIST", array: TRUE}}}

"Person"

{count: 2, relationships: {ACTED_IN: {count: 9, properties: {roles: {existence: FALSE, type: "LIST", array: TRUE}}, direction: "out", labels: ["Movie"]}}, type: "node", properties: {name: {existence: FALSE, type: "STRING", indexed: FALSE, unique: FALSE}, born: {existence: FALSE, type: "INTEGER", indexed: FALSE, unique: FALSE}}, labels: []}

"sameName (RELATIONSHIP)"

{"count":1,"type":"relationship","properties":{"alfa":{"existence":false,"type":"STRING","array":false}}}

"sameName"

{count: 2, relationships: {"sameName": {count: 1, properties: {alfa: {existence: false, type: "STRING", array: false}}, direction: "out", labels: ["sameName"]}}, type:"node", properties: {id: {existence: false,type: "INTEGER", indexed: false,unique: false}},labels: []}

Sample config usage example

Given the following graph:

CREATE (:Foo), (:Other)-[:REL_0]->(:Other), (:Other)-[:REL_1]->(:Other)<-[:REL_2 {baz: 'baa'}]-(:Other), (:Other {alpha: 'beta'}), (:Other {foo:'bar'})-[:REL_3]->(:Other)

Without sample parameter we receive:

CALL apoc.meta.schema()
YIELD value RETURN value["Other"] as value;
Table 3. Results
value 
{
    "count": 8,
    "relationships": {
        "REL_2": {
            "count": 1,
            "properties": {
                "baz": {
                    "existence": false,
                    "type": "STRING",
                    "array": false
                }
            },
            "direction": "out",
            "labels": [
                "Other",
                "Other"
            ]
        },
        "REL_3": {
            "count": 1,
            "properties": {

            },
            "direction": "out",
            "labels": [
                "Other",
                "Other"
            ]
        },
        "REL_0": {
            "count": 1,
            "properties": {

            },
            "direction": "out",
            "labels": [
                "Other",
                "Other"
            ]
        },
        "REL_1": {
            "count": 1,
            "properties": {

            },
            "direction": "out",
            "labels": [
                "Other",
                "Other"
            ]
        }
    },
    "type": "node",
    "properties": {
        "alpha": {
            "existence": false,
            "type": "STRING",
            "indexed": false,
            "unique": false
        },
        "foo": {
            "existence": false,
            "type": "STRING",
            "indexed": false,
            "unique": false
        }
    },
    "labels": []
}

Otherwise, with sample: 2 we obtain (the result can change):

CALL apoc.meta.schema({sample: 2})
YIELD value RETURN value["Other"] as value
Table 4. Results
value 
{
  "count": 8,
  "relationships": {
    "REL_1": {
      "count": 1,
      "properties": {},
      "direction": "out",
      "labels": [
        "Other",
        "Other"
      ]
    }
  },
  "type": "node",
  "properties": {
    "alpha": {
      "existence": false,
      "type": "STRING",
      "indexed": false,
      "unique": false
    }
  },
  "labels": []
}