Querying AlloyDB Data as a Graph

A step-by-step tutorial to using PuppyGraph to query data in AlloyDB

Summary

In this tutorial, you will:

  • Create a AlloyDB database and load it with example data;

  • Start a PuppyGraph Docker container and query the AlloyDB data as a graph.

Prerequisites

  • Please ensure that docker is available.

  • You need an account of Google Cloud Platform with access to AlloyDB.

  • Accessing the PuppyGraph Web UI requires a browser.

Deployment

▶️ Run the following command to start PuppyGraph:

docker run -p 8081:8081 -p 8182:8182 -p 7687:7687 -d --name puppy --rm --pull=always puppygraph/puppygraph:stable

Create a cluster of AlloyDB

▶️ Create a cluster of AlloyDB in GCP web console.

Certain configuration options remain editable after cluster creation, including connection settings. Access via public IP address necessitates the implementation of an authenticated network. For demonstration purposes, we may just use an plaintext connection.

Data Preparation

This tutorial is designed to be comprehensive and standalone, so it includes steps to populate data in AlloyDB. In practical scenarios, PuppyGraph can query data directly from existing tables in your AlloyDB databases.

▶️ Connect to the database in AlloyDB by tools like psql. The default username and database name are both postgres if you did not change them in the previous step.

psql -h <primary-instance-ip> -p <port> -U <username> -d <database-name>

▶️ Create the demo graph.

create schema modern;
create table modern.person (id text, name text, age integer);
insert into modern.person values
                              ('v1', 'marko', 29),
                              ('v2', 'vadas', 27),
                              ('v4', 'josh', 32),
                              ('v6', 'peter', 35);

create table modern.software (id text, name text, lang text);
insert into modern.software values
                                ('v3', 'lop', 'java'),
                                ('v5', 'ripple', 'java');

create table modern.created (id text, from_id text, to_id text, weight double precision);
insert into modern.created values
                               ('e9', 'v1', 'v3', 0.4),
                               ('e10', 'v4', 'v5', 1.0),
                               ('e11', 'v4', 'v3', 0.4),
                               ('e12', 'v6', 'v3', 0.2);

create table modern.knows (id text, from_id text, to_id text, weight double precision);
insert into modern.knows values
                             ('e7', 'v1', 'v2', 0.5),
                             ('e8', 'v1', 'v4', 1.0);

The above SQL creates the following tables under the modern schema:

idnameage

v1

marko

29

v2

vadas

27

v4

josh

32

v6

peter

35

Graph Schema

▶️ If PuppyGraph Web UI is available, you can create graph schema using Graph Schema Builder or upload graph schema JSON file directly.

Note that you need to change JDBC URI according to the IPs of your cluster. It can be the IP of primary instance or the read pool.

Alternative: Schema Uploading via CLI

▶️ Alternatively, create a schema.json file with AlloyDB connection information filled. Then run the following command to upload the schema file:

schema.json
{
    "catalogs": [
      {
        "name": "alloydb_data",
        "type": "postgresql",
        "jdbc": {
          "username": "postgres",
          "password": "7g9KJ83JPtjUE1",
          "jdbcUri": "jdbc:postgresql://<alloydb_uri>:<alloydb_port>/postgres",
          "driverClass": "org.postgresql.Driver"
        }
      }
    ],
    "vertices": [
      {
        "label": "person",
        "mappedTableSource": {
          "catalog": "alloydb_data",
          "schema": "modern",
          "table": "person",
          "metaFields": {
            "id": "id"
          }
        },
        "attributes": [
          {
            "type": "Int",
            "name": "age"
          },
          {
            "type": "String",
            "name": "name"
          }
        ]
      },
      {
        "label": "software",
        "mappedTableSource": {
          "catalog": "alloydb_data",
          "schema": "modern",
          "table": "software",
          "metaFields": {
            "id": "id"
          }
        },
        "attributes": [
          {
            "type": "String",
            "name": "lang"
          },
          {
            "type": "String",
            "name": "name"
          }
        ]
      }
    ],
    "edges": [
      {
        "label": "knows",
        "mappedTableSource": {
          "catalog": "alloydb_data",
          "schema": "modern",
          "table": "knows",
          "metaFields": {
            "id": "id",
            "from": "from_id",
            "to": "to_id"
          }
        },
        "from": "person",
        "to": "person",
        "attributes": [
          {
            "type": "Double",
            "name": "weight"
          }
        ]
      },
      {
        "label": "created",
        "mappedTableSource": {
          "catalog": "alloydb_data",
          "schema": "modern",
          "table": "created",
          "metaFields": {
            "id": "id",
            "from": "from_id",
            "to": "to_id"
          }
        },
        "from": "person",
        "to": "software",
        "attributes": [
          {
            "type": "Double",
            "name": "weight"
          }
        ]
      }
    ]
  }
curl -XPOST -H "content-type: application/json" --data-binary @./schema.json --user "puppygraph:puppygraph123" localhost:8081/schema

The response shows that graph schema has been uploaded successfully:

{"Status":"OK","Message":"Schema uploaded and gremlin server restarted"}

Querying the Graph

In this tutorial we will use the Gremlin query language to query the Graph. Gremlin is a graph query language developed by Apache TinkerPop. Prior knowledge of Gremlin is not necessary to follow the tutorial. To learn more about it, visit https://tinkerpop.apache.org/gremlin.html.

▶️ Click on the Query panel the left side. The Gremlin Query tab offers an interactive environment for querying the graph using Gremlin.

Queries are entered on the left side, and the right side displays the graph visualization.

The first query retrieves the property of the person named "marko".

▶️ Copy the following query, paste it in the query input, and click on the run button.

g.V().has("name", "marko").valueMap()

The output is plain text like the following:

Rows: 1
age              29
name             marko

Now let's also leverage the visualization. The next query gets all the software created by people known to "marko".

▶️ Copy the following query, paste it in the query input, and click on the run button.

g.V().has("name", "marko")
  .out("knows").out("created").path()

The output is as follows. There are two paths in the result as "marko" knows "josh" who created "lop" and "ripple".

Alternative: Querying the graph via CLI

Alternatively, we can query the graph via CLI.

▶️ Execute the following command to access the PuppyGraph Gremlin Console

docker exec -it puppy ./bin/console

The welcome screen appears as follows:

  ____                                     ____                          _
 |  _ \   _   _   _ __    _ __    _   _   / ___|  _ __    __ _   _ __   | |__
 | |_) | | | | | | '_ \  | '_ \  | | | | | |  _  | '__|  / _` | | '_ \  | '_ \
 |  __/  | |_| | | |_) | | |_) | | |_| | | |_| | | |    | (_| | | |_) | | | | |
 |_|      \__,_| | .__/  | .__/   \__, |  \____| |_|     \__,_| | .__/  |_| |_|
                 |_|     |_|      |___/                         |_|
Welcome to PuppyGraph!
version: 0.26

To Learn more about the graph schema:
- Use graph.show() to list all the vertex and edge labels.
- Use graph.show('$FOO') to list all the vertex and edge labels related to $FOO.
- Use graph.describe('$BAR') to list all the attributes of the label $BAR.

See https://tinkerpop.apache.org/gremlin.html to learn more about the Gremlin query language.
Here are some example queries for exploring the graph:
- Use g.V() to list all the vertices.
- Use g.E() to list all the edges.
- Use g.V().count() to get the total number of vertices.
- Use g.E().count() to get the total number of edges.
- Use g.V('$ID').out() to find out vertices that are reachable in 1-hop from the vertex $ID. For example, g.V('person[v1]').out() will find out 1-hop reachable vertices from 'person[v1]'.
- Use g.V('$ID').out().out() similarly to find out 2-hop reachable vertices from the vertex $ID.

puppy-gremlin>

▶️ Run the following queries in the console to query the Graph.

g.V().has("name", "marko").valueMap()

Properties of the person named "marko":

puppy-gremlin> g.V().has("name", "marko").valueMap()
Done! Elapsed time: 0.059s, rows: 1
==>map[age:29 name:marko]

▶️ To exit PuppyGraph Gremlin Console, enter the command:

:exit

Cleaning up

▶️ Run the following command to stop and clean up the container.

docker stop puppy
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