Using an Algorithm

This page provides information on how to use a TigerGraph Graph Data Science (GDS) Library algorithm.

All GDS algorithms can be found at tigergraph/gsql-graph-algorithms on GitHub in the algorithms folder. The algorithms are divided into several categories. Each algorithm has its own folder, where you can find the implementation of the algorithm, any user-defined functions required to install the algorithm, or different versions of the algorithm if they exist.

GDS Library algorithms are implemented in GSQL as GSQL queries. Therefore, the process to run an algorithm query is the same as the process to run any other query.

The algorithm library is included, ready to install, with the TigerGraph database. Version 3.8 offers the library in an additional format, as packaged template queries. The packaging simplifies the installation and management of the library, and new CALL command performs just-in-time compilation of the template queries to offer even better performance than before. TigerGraph is continually improving its library. To get the latest version, users can always go to our GitHub repository: GSQL Graph Algorithm Repository.

Most of the algorithm queries provide multiple output formats. You usually have the option to output one or more of the following:

  • JSON output to console

  • CSV output to a file

  • Results written to an attribute of vertices or edges

If you are running an algorithm on a TigerGraph Cloud cluster, you need to use AdminPortal to download the algorithm’s output files to your local machine. See Download GSQL Output File for details.

Packaged template queries

Packaged template queries are a new, simplified method for working with algorithms that are preinstalled in a TigerGraph instance. They use a new keyword, CALL, to run with just-in-time compilation for improved performance.

The syntax is very similar to using a package in Python.

Import and explore template queries

In TigerGraph version 3.8.0 and later, run the following command to import the query package.

GSQL > IMPORT PACKAGE GDBMS_ALGO.*

Wait a few moments for the queries to load. Run SHOW PACKAGE to check that installation was successful.

GSQL > SHOW PACKAGE

Packages on global:
  - GDBMS_ALGO

Run SHOW PACKAGE again, this time specifying GDBMS_ALGO, to see the list of sub-packages. Each sub-package corresponds to a category of GDS algorithms.

GSQL > SHOW PACKAGE GDBMS_ALGO

Packages GDBMS_ALGO:
  - Sub-Packages:
    - centrality
    - classification
    - community
    - graphML
    - path
    - similarity
    - topological_link_prediction

By specifying a sub-package in the IMPORT PACKAGE command and adding the asterisk *, you can choose to import only a subset of the package. The following command imports only the community sub-package.

GSQL > IMPORT PACKAGE GDBMS_ALGO.community.*

Use dot notation to explore each sub-package.

GSQL > SHOW PACKAGE GDBMS_ALGO.centrality

Packages GDBMS_ALGO.centrality:
  - Object:
      - Packaged Queries:
        - article_rank(string v_type, string e_type, float max_change, int maximum_iteration, float damping, int top_k, bool print_results, string result_attribute, string file_path)
        - betweenness_cent(set<string> v_type_set, set<string> e_type_set, string reverse_e_type, int max_hops, int top_k, bool print_results, string result_attribute, string file_path, bool display_edges)
...

Run a packaged query

To run (or 'call') a packaged query, you must first be using a graph. Run the GSQL command USE GRAPH <graph name> first.

Use the CALL command with a specific query name from a package and include the parameters.

GSQL > USE GRAPH ldbc_snb
Using graph `ldbc_snb`

GSQL > CALL GDBMS_ALGO.community.louvain(["Person"],["KNOWS"],"weight",10,"","",true)

In this example, we call the Louvain algorithm, specifying:

  • A set of strings ["Person"] as the vertex types to use

  • A set of strings ["KNOWS"] as the edge types to traverse

  • A string "weight" as the edge weight attribute

  • An integer 10 as the maximum limit of iterations

  • An empty string "" for the result attribute, ensuring nothing will be written to any vertices

  • An empty string "" for the file path, ensuring the results will not be written as a file

  • A boolean true to print the results to the console in JSON format.

The first time you call an algorithm on a particular graph and with a particular set of graph schema elements (vertex types, edge types, and/or vertex or edge attributes), it goes through a short just-in-time-compilation process to optimize the execution plan for the query.

If you run the same algorithm with the same graph schema elements (regardless of modification to other non-schema parameters such as number of iterations), it does not require compilation and immediately runs the algorithm query.

Therefore, in the previous example, changing any of the first three parameters requires recompilation, but changing any of the other parameters runs the query without needing compilation.

On the ldbc_snb graph, the results look like this after the query runs:

------Running query------

{
  "error": false,
  "message": "",
  "version": {
    "schema": 0,
    "edition": "enterprise",
    "api": "v2"
  },
  "results": [
    {"AllVertexCount": 9163},
    {"InitChangeCount": 0},
    {"VertexFollowedToCommunity": 355},
    {"VertexFollowedToVertex": 0},
    {"VertexAssignedToItself": 729},
    {"FinalCommunityCount": 9537}
  ]
}

GraphStudio version 3.8 does not support using the CALL command for packaged template queries. To install queries on GraphStudio, use the non-packaged method in the next section.

Non-packaged queries

TigerGraph provides an open-source GitHub repository with the full text of each query algorithm. These queries can be installed just like any other GSQL query.

Moreover, the source code for most algorithms is included in the file system of the database. Users can choose to install some or all of these queries with a single GraphStudio operation. This automated installation will automatically take care of any subquery or UDF dependencies.

Graph Data Science Library Queries

Check for data or schema constraints

Most algorithm queries in the GDS Library are schema-free, meaning that you are able to run the query on any schema. However, some algorithms have certain schema or data constraints by nature. Make sure to read the documentation for the algorithm to determine the following:

  • Does the algorithm require edges to be directed/undirected?

  • Does the algorithm require edges to be weighted/unweighted?

  • Does the algorithm require any vertex type to have an attribute of a certain data type?

  • Does the algorithm require your data to have been processed in a certain way before it runs?

For example, k-Nearest Neighbors runs on graphs with either directed or undirected edges, but the edges must have a weight attribute.

Another example is the Fast Random Projection algorithm, which expects the vertex type to have an attribute of type LIST<DOUBLE> if you want to store the embedding results to your graph data.

Create query

If the algorithm you want is not yet installed in your TigerGraph instance, and if you do not use the GraphStudio simplified installation process, then you can install the algorithm as you would add any query to the database.

Follow these instructions to first create, then install the query:

You can create the query in the following ways:

  • GSQL Shell

  • GraphStudio

  1. Locate the query in the GDS Library GitHub repository. It is a .gsql file named after the query.

  2. Copy the entire contents of the query file, which is the command to create the query, and paste it into a file on the machine running TigerGraph.

  3. Log in to the GSQL shell as a user with query writing privileges for the graph on which you want to create the query.

  4. Run @<file path> from the GSQL shell, and replace <file path> with the absolute path to the file where you copied the query. For example, if your filepath is /home/tigergraph/query/pagerank.gsql, run @/home/tigergraph/query/pagerank.gsql from the GSQL shell.

Saving a query in GraphStudio does not create the query in GSQL.

  1. Locate the query in the GDS Library GitHub repository. It is a .gsql file named after the query.

  2. Copy the entire content of the query file. This is the command to create the query.

  3. Log in to GraphStudio as a user with query writing privileges for the graph on which you want to create the query.

  4. Click Global View in the top-left corner and choose the graph to use.

  5. Click Write Queries on the left side navigation. Click + to add a new query and enter the query name. This name must be the same as the name in the CREATE QUERY command

  6. Paste the CREATE QUERY command into the query and save the query.

Install query

Installing a query allows the algorithm query to access all features offered by the GSQL Query language. It also increases the performance of the query.

To install a query, run INSTALL QUERY <query name> in the GSQL shell. Alternatively, you can click Install on the Write Query page of GraphStudio.

Install query in distributed mode

If you are running the query on a TigerGraph cluster, you may consider installing the query in distributed mode.

In general, distributed mode is likely to improve the performance of a query if the query meets the following conditions:

  • The query starts at a very large set of starting point vertices.

  • The query performs many hops.

For example, algorithms that compute a value for every vertex or one value for the entire graph should use distributed mode. This includes PageRank, Centrality, and Connected Component algorithms.

To install a query in distributed mode in the GSQL shell, run command INSTALL QUERY <query_name> -DISTRIBUTED. To install a query in distributed mode from GraphStudio, change the CREATE QUERY at the beginning of the command to CREATE DISTRIBUTED QUERY, and then click Install.

Run query

Once the query has been installed, you can run the query on your graph data. Installing a query also creates a REST endpoint you can use to call the query.