Graql Compute Queries

A compute query executes a Pregel algorithm to determine information about the knowledge graph in parallel. Called within the Graql shell or dashboard, the general syntax is:

compute [goal] [subgraph]; (using [strategy] where [modifiers];)
  • goal can be any of the available statistics or graph queries.
  • subgraph is a comma separated list of types to be visited by the Pregel algorithm.

Additionally, for graph queries

  • strategy is actual algorithm used
  • modifiers are different depending on the specific query and algorithm.

The simplest query count can be executed using the following:

compute count;

The following query compute the clusters, in the subgraph containing only person and marriage, using connected component, and return the members of each cluster.

compute cluster in [person, marriage], using connected-component, where members=true;

Subgraph

The subgraph syntax is provided to control the types that a chosen algorithm operates upon. By default, the compute methods include instances of every type in the calculation. Using the in keyword followed by a comma separated list of types will restrict the calculations to instances of those types only.

For example,

compute count in person;

will return just the number of instances of the concept type person. Subgraphs can be applied to all compute queries and therefore are different to strategy and modifiers.

The specific compute queries fall into two main categories and more information is given in the sections below.

Available Statistics Methods

The following methods are available to perform simple statistics computations. A summary of the statistics algorithms is given in the table below.

Algorithm Description
count Count the number of instances.
max Compute the maximum value of an attribute.
min Compute the minimum value of an attribute.
mean Compute the mean value of an attribute.
median Compute the median value of an attribute.
std Compute the standard deviation of an attribute.
sum Compute the sum of an attribute.

For further information see the statistics queries.

Available Graph Queries

The following algorithms all compute values based on the structure of the graph. A summary of the graph algorithms is given in the table below.

Algorithm Description
cluster Find the clusters of instances.
centrality Compute the centrality of each instance in the graph.
path Find the shortest path(s) between two instances.

For further information see the individual sections.

Tags: graql