DataStax Graph (DSG) QuickStart using DataStax Studio or Gremlin console.
QuickStart Introduction
QuickStart Introduction
Graph databases are useful for discovering simple and complex relationships between objects.
Relationships are fundamental to how objects interact with one another and their environment.
Cassandra can store large distributed datasets, and DataStax Graph (DSG) is Graph for
Cassandra. DSG allows Cassandra data to be traversed with complex queries that are not
possible with the Cassandra Query Language (CQL) or are the equivalent of multiple SQL JOINS
required in a traditional RDBMS.
This QuickStart explores DSG from a data model that leads to schema, inserting data, and
simple queries that show off the power of graph databases. Starting with DSG 6.8, the same
data can be queried with either Gremlin or CQL, increasing the useability of the same data for
different uses. However, for this QuickStart, we'll use Gremlin as the main language of
interaction.We'll start by discussing what a graph database actually is.
Graph databases consist of three elements:
vertex
A vertex is an object, such as a person, location, automobile, recipe, or anything
else you can think of as nouns.
edge
An edge defines the relationship between two vertices. A person can create software,
or an author can write a book. Typically an edge is equivalent to a verb.
property
A key-value pair that describes some attribute of either a vertex or an edge. A
property key is used to describe the key in the key-value pair.
Vertices, edges, and properties can have properties; for this reason, DataStax Graph is
classified as a property graph. The properties for elements are an important element of
storing and querying information in a property graph.
Property graphs are typically quite large, although the nature of querying the graph varies
depending on whether the graph has large numbers of vertices, edges, or both vertices and
edges. To get started with graph database concepts, a toy graph is used for simplicity.
The example used here explores the world of food.
Figure 1:
Elements are labeled to distinguish the type of vertices and edges in a graph database using
vertex labels and edge labels. A vertex labeled person holds
information about an author or reviewer or someone who ate a meal. An edge between an
person and a book is labeled authored. Specifying appropriate labels is
an important step in graph data modeling.
Vertices and edges generally have properties. For instance, a person vertex can have
properties name and gender. Edges can also have properties. A created
edge can have a create_date property that identifies when the adjoining recipe
vertex was created.
Information in a graph database is retrieved using graph traversals. Graph
traversalswalk a graph with a single or series of traversal steps from a defined starting
point and filter each step until returning a result.
Start the Gremlin console. If DataStax Graph was installed as a
package, run the command. If installed from a tarball, run from the
<install_directory>/bin.
Gremlin console sends all commands typed at the prompt to the Gremlin
Server that will process the commands. To exit the Gremlin console,
use :exit.
QuickStart Configuration
Configure DataStax Graph to run QuickStart.
To use DSG, a graph must be created. Using DataStax Studio, either a pre-populated
notebook, DataStax Graph 6.8 QuickStart, can be used, or a new notebook can
be created. Instructions for both are provided. In addition, if Gremlin console is
used for this QuickStart, a graph must be created, and an alias to set a graph
traversal source must be executed in order for the code examples to work. The set
alias identifies the graph in which all schema and queries are executed.
Important: Should Gremlin console be exited, you must set the alias
configuration again before proceeding.
DataStax Studio is a visual browser-based tool that provides a better understanding
of the interconnectedness of the graph data. The Gremlin console is a command-line
interface that is better suited to automation of checking and verifying query
results and scripting. For initial exploration and development, Studio is highly
recommended, whereas greater familiarity with DSG will make Gremlin console handy
for automated verification.
Procedure
Create a Studio notebook and configure a graph for the QuickStart. If you are
using Gremlin console, skip to the
instructions for set up..
This tutorial exists as a Studio notebook, DataStax Graph 6.8
QuickStart, so that you do not have to create a notebook.
However, in Studio, creating a
notebook is simple. If running Studio on a Graph node, the
default connection of localhost works, otherwise create a connection for the
node desired. Each notebook is connected to a particular graph. Multiple
notebooks can be connected to the same graph, or multiple notebooks can
be created to connect to different graphs.
Studio can create a graph from a number of different places. You
can create the graph as the last step during notebook creation, or open
a notebook and add a graph. Either way, several choices must be
configured. The graph must be given a name, graph type designated, and
replication factor settings selected.
Graph type: Core is the default and preferred graph engine for
DataStax Graph 6.8. It allows users to access their graph data
via CQL as well as Gremlin. The schemas for storing Core and
Classic graphs are different, so Classic should be chosen only
if a notebook will use graph data created using DataStax Graph
6.7 or earlier.
Replication factor: The default is set to 1. Production clusters
and multi-datacenter clusters need a higher replication
factor.
Replication strategy: The default is NetworkTopologyStrategy. In
general, this default is the good option.
Create a graph in Gremlin console and configure the graph for the
QuickStart.
Create a graph to hold the data. The system commands are used to
run commands that affect graphs in DSG.
system.graph('food_qs').
ifNotExists().
create()
==>OK
Once a graph exists, a graph traversal g is configured that will
allow graph traversals to be executed. Graph traversals are used to
query the graph data and return results. The graph traversal can be
bound to either the standard OLTP engine or the OLAP engine. In order to
execute any schemas or other queries in the Gremlin console, a graph
traversal must be executed first. Configure a graph traversal
g to use the default graph traversal setting, which
is food_qs.g.
:remote config alias g food_qs.g
==>g=food_qs.g
Important: As with all queries in Graph, if you are
using Gremlin console, alias the graph traversal g to a graph with
:remote config alias g food_qs.g before running any
commands.
When creating a new graph, to check what graphs already exist,
use:
system.graphs()
==>food_qs
QuickStart Simple example
Simple DataStax Graph example.
Let's start with a simple example from the recipe data model. The data is composed of
two vertices, one person who is an author (Julia Child) and one book (The
Art of French Cooking, Vol. 1) with an edge between them to identify that
Julia Child authored that book. We'll supply schema, insert data using graph
traversals with g.addV() and g.addE(), then
examine the data and run queries.
Execute all code samples using either Studio or Gremlin console by copy/pasting the
codeblocks below.
Important: As with all queries in Graph, if you are
using Gremlin console, alias the graph traversal g to a graph with
:remote config alias g food_qs.g before running any
commands.
Procedure
Create the schema for a vertex labelperson, along with the vertex properties and their data
types:
The vertex label defines the Cassandra Query Language (CQL) table name that
will store person vertices. Each property consists of a
property key and data type that define CQL columns in the table. Both the
vertex label and the property definitions must adhere to CQL naming syntax. Like CQL tables, a single
or multiple partition
key must be defined with at least one property using
partitionBy property_name.
Clustering columns may also be defined using a similar clusteringBy
property_name. The partition key defines
where in the cluster the data will reside, while the clustering columns
define the sort order of the data within a partition.
A new feature of DataStax Graph 6.8 is the use of collections as data types
for properties. The DSE 6.7 Graph and earlier concepts of meta-properties and multi-properties
are replaced with collections or nested collections. For instance,
country is now defined as a list of tuples, to store
multiple records of a country, start_date and end_date
in which a person has lived.
A successful schema command will
return:
==> OK
Insert a vertex for Julia Child using a g.addV() command.
g.addV('person').
property('person_id', 'e7cd5752-bc0d-4157-a80f-7523add8dbcd' as UUID).
property('name', 'Julia CHILD').
property('gender','F').
property('nickname', ['Jay', 'Julia'] as Set).
property('country', [['USA', '1912-08-12' as LocalDate, '1944-01-01' as LocalDate] as Tuple, ['Ceylon', '1944-01-01' as LocalDate, '1945-06-01' as LocalDate] as Tuple, ['France', '1948-01-01' as LocalDate, '1960-01-01' as LocalDate] as Tuple, ['USA', '1960-01-01' as LocalDate, '2004-08-13' as LocalDate] as Tuple])
The vertex label person identifies the type of vertex to add
along with the property key-value pairs created. Note that some properties
include additional information to define the data type conversion from a
string to the required type.
Using a set, the property nickname is defined with
multiple values, a replacement for previously supported
multi-properties.
The Studio result:
Tip: In Studio, the result can be displayed using different views:
Raw JSON, Table, or Graph. Explore the options.
This command and the next one will return results similar to the actions
above for creating a person.
Insert a book into the graph:
g.addV('book').
property('book_id',1001).
property('name',"The Art of French Cooking, Vol. 1").
property('publish_year', 1961).
property('category', ['French', 'American'] as Set)
The Studio result:
As with the person vertex, you can see all the information about the book
vertex created. In Graph view, use the
Settings button (the gear) to change the display
label for person by entering Chef {{name}}. Change the book
display label with book:{{{[name]}}}. Change the icon for
books to a book icon as shown here with the Style-Vertex
Shape menu. To set graph display names more generally, look
for “Manage Global Defaults” under the Display
Names
The Gremlin console result:
==>v[dseg:/book/1001]
Add schema for the edge between the two vertices for a person authoring a
book:
In this query, each vertex is defined and given a temporary label,
person as a and book
as b, and the temporary labels used to add the edge with
addE().from().to(). The partition key and value for
each vertex must be included in the query.
Use Graph view in Studio to see the relationship.
Scroll over elements to display additional information.
In Studio, the results are easy to visualize and check. In the Gremlin console,
ensure that the data inserted for the vertices is correct by checking with a
query that gets all vertices. All of the commands can be executed in Studio as
well as Gremlin console. In production, DSG prevents expensives queries from
processing. In development, include the with("label-warning",
false) so that a query can run without specifying vertex labels.
A much more useful query would check the data for a vertex using a simple bit
of information, like a person's name. However, without adding an index for
name, this query will fail, because the value for the
primary key person_id is not supplied. For example:
g.V().has('person', 'name', 'Julia CHILD')
Two
alternatives exist, a development mode for running queries and a modifier
mode with('allow-filtering'). The dev mode
is intended for early exploration, before appropriate indexes have been
settled
upon:
You'll notice when you tried the command g.V().has('person', 'name',
'Julia CHILD'), you got an error message that provides the index
required to do the query in a production-safe manner:
Note that while the index has been created successfully, it may not yet be finished building.
Alternatively, use '.waitForIndex(<optionalTimeout>).create()' during index creation to wait for the index to be built.
OK
The index is created as a materialized view table, with a partition key of
the column to index and a clustering column of the original table's
partition key. Once the index exists, the query will run without doing a
full scan. Indexing is a large topic that is
worth reading about, as efficient queries depend on indexes.
Notice that the original query about Julia Child will now run without warnings,
after the index is created, and returns the same information as the development
queries:
g.V().has('person', 'name', 'Julia CHILD')
We now have data! Let's see what kind of graph queries can be executed. First,
check the data using the unique partition key:
While
the partition key will be useful in some queries, generally queries use more
user-friendly data, like name or category,
to find vertices.
Two other useful traversals are elementMap() and
valueMap() which print the key-value listing of each
property value for specified vertices.
g.V().hasLabel('person').elementMap()
In Studio:
CAUTION: Using elementMap()
or valueMap() without specifying properties can result in
slow query latencies, if a large number of property keys exist for the
queried vertex or edge. Specific properties can be specified, such as
elementMap('name') or
valueMap('name').
Using valueMap() returns similar information in a slightly
different container, but doesn't include the element id and
label. Try out the command and compare! In DSG 6.8.0,
valueMap() is deprecated, so use
elementMap().
QuickStart Vertex and edge counting
Methods for counting vertices and edges in DataStax Graph.
There are different methods for accomplishing vertex and edge counts in DataStax
Graph (DSG). Examples here will show how to use the Gremlin count() command as a
transactional query. If large datasets are queried, analytical (OLAP) queries using
DSE Analytics should be considered.
A transactional Gremlin query can be used to check the number of vertices that exist
in the graph, and is useful for exploring small graphs. However, such a query scans
the full graph, traversing every vertex, and should not be run on large
graphs! If multiple DSE nodes are configured, this traversal step intensively walks
all partitions on all nodes in the cluster that have graph data.
Warning: Remember, this method is not appropriate for large graphs or
production operations.
An analytical Gremlin query can be used to check the number of vertices that exist in
any graph, large or small, and are much safer for production operations. The queries
will be written like transactional Gremlin queries, but executed with the analytic
Spark engine. In Studio, use the execution button to select OLTP or OLAP. In Gremlin
console, set the graph traversal source to OLAP before executing the query. DSE
Analytics must be enabled on the cluster to use this option.
Vertex and edge counts can also be queried directly from the CQL tables for each
vertex label and edge label, once the schema is defined.
Important: As with all queries in Graph, if you are
using Gremlin console, alias the graph traversal g to a graph with
:remote config alias g food_qs.g before running any
commands.
Procedure
Transactional Gremlin vertex count()
Use the traversal step count(). A graph traversal
g is chained with V() to retrieve all
vertices and count() to compute the number of vertices.
Chaining executes sequential traversal steps in the most efficient order.
g.V().count()
In Studio, the result is:In Gremlin console, the result
is:
==>2
Note: An
instructional warning will be thrown, advising that this command can
result in long latency if run without assisting
options.
[warn] This traversal could read elements without a label restriction.
This may degrade performance if many element labels are involved. Suggestions:
- Add hasLabel steps to the traversal where vertices are read or edges traversed. Examples:
Instead of V(), use V().hasLabel('vertex_label')
Instead of out(), use out('edge_label')
- Suppress this warning by beginning the traversal by g.with("label-warning", false).
Transactional Gremlin edge counts
To do an edge count with Gremlin, replace V() with
E():
g.E().count()
In Studio, the result is:In Gremlin console, the result
is:
==>1
Note: An
instructional warning will be thrown, advising that this command can
result in long latency if run without assisting
options.
[warn] This traversal could read elements without a label restriction.
This may degrade performance if many element labels are involved. Suggestions:
- Add hasLabel steps to the traversal where vertices are read or edges traversed. Examples:
Instead of V(), use V().hasLabel('vertex_label')
Instead of out(), use out('edge_label')
- Suppress this warning by beginning the traversal by g.with("label-warning", false).
Analytical Gremlin vertex count()
Restriction: The
following steps will only execute if DSE Analytics is enabled. Do not run if
only Graph is enabled on the cluster.
To use Studio, configure the Run option to "Execute using analytic engine
(Spark)" before running the query. A result similar to the tranactional query
will result.
To use Gremlin console, first configure the traversal to run an analytical
query:
:remote config alias g food_qs.a
where food_qs.a denotes that the graph will be used for
analytic purposes. Then run the
command:
g.V().count()
Important: If DSE Analytics is not enabled, this query will
fail.
Vertex and edge counts using CQL
Use the CQL statement SELECT count(*) to retrieve the count of
either vertices or edges with an appropriate CQL table. For instance, retrieve
the count of person vertices:
SELECT count(*) FROM food_qs.person;
In
order to retrieve a count of all vertices, query each vertex label
table.
count
-------
1
(1 rows)
Retrieve the count of person->authored->book edges:
SELECT count(*) FROM food_qs.person__authored__book;
In
order to retrieve a count of all vertices, query each vertex label
table.
In Studio: In Gremlin
console:
count
-------
1
(1 rows)
QuickStart Graph schema
Working with graph schema.
Before adding more data to the graph, let's stop and talk about schemas, which define
both vertex labels and edge labels along with their associated properties and data
types. User-defined types (UDTs) are a feature of DSG and must be created before use
as a data type in schema. Schema creation also includes index creation. Indexes play
an important role in making graph traversals efficient and fast. See creating schema and creating indexes for more information.
Schema can also be modified after creation, adding properties to vertex labels or
edge labels with addProperty() and alter().
Let's create additional schema for the food graph. These steps demonstrate
dropping and creating schema.
Important: As with all queries in Graph, if you are
using Gremlin console, alias the graph traversal g to a graph with
:remote config alias g food_qs.g before running any
commands.
Procedure
Drop the previously-created schema. The new schema could be added, but this
step ensures that no leftover schema or data corrupts the graph.
schema.drop()
Dropping schema will drop all data
associated with the schema. Schema can be also be dropped individually for
vertex labels, edge labels, properties and indexes.
User-defined type (UDT) schema
Create some useful UDTs for the vertex labels in the next step:
// VERTEX LABELS
// ********
// SYNTAX:
// schema.vertexLabel('vertexLabel')
// [ .ifNotExists() ]
// .partitionBy('propertyName', propertyType) [ ... ]
// [ .clusterBy('propertyName', propertyType) ... ]
// [ .property('propertyName', propertyType) ]
// [ .create() | .describe() | .addProperty('propertyName', propertyType).alter() ]
// SINGLE PARTITION KEY Vertex Labels
// macro_goal is a list of carbohydrate, protein, fat
// country is a list of tuple of country, start date, end date; replacement for a meta-property in classic graph
// Also, country demonstrates multi-property, being a list of countries and dates lived in
// country, start_date, end_date
// badge is a replacement for a meta-property in earlier versions
// level:year, such as gold:2015, expert:2019, or sous-chef:2009 (mainly expect to use for reviewers)
// NEED TO ADD NEW FEATURE DSP_18625
// .tableName('personTable')
// START-createVL_person
schema.vertexLabel('person').
ifNotExists().
partitionBy('person_id', Uuid).
property('name', Text).
property('gender', Text).
property('nickname', setOf(Text)).
property('cal_goal', Int).
property('macro_goal', listOf(Int)).
property('country', listOf(tupleOf(Text, Date, Date))).
property('badge', mapOf(Text, Date)).
create()
// END-createVL_person
// book_discount was a property in the old data model that had a ttl; I'm including here to use the same datasets
// Add as an added property
//property('book_discount', Text).
// START-createVL_book
schema.vertexLabel('book').
ifNotExists().
partitionBy('book_id', Int).
property('name', Text).
property('publish_year', Int).
property('isbn', Text).
property('category', setOf(Text)).
create()
// END-createVL_book
// Going to create vertexLabel recipe through converting a CQL table to a VL
// Although the notebook shows creating a table for recipe with CQL, then converting,
// this is the Gremlin schema to make the recipe vertex label
// START-createVL_recipe
schema.vertexLabel('recipe').
ifNotExists().
partitionBy('recipe_id', Int).
property('name', Text).
property('cuisine', setOf(Text)).
property('instructions', Text).
property('notes', Text).
create()
// END-createVL_recipe
// START-createVL_item_meal
schema.vertexLabel('meal_item').
ifNotExists().
partitionBy('item_id', Int).
property('name', Text).
property('serv_amt', Text).
property('macro', listOf(Int)).
property('calories', Int).
create()
// END-createVL_item_meal
// START-createVL_ingredient
schema.vertexLabel('ingredient').
ifNotExists().
partitionBy('ingred_id', Int).
property('name', Text).
create()
// END-createVL_ingredient
// START-createVL_home
schema.vertexLabel('home').
ifNotExists().
partitionBy('home_id', Int).
property('name', Text).
create()
// END-createVL_home
// START-createVL_store
schema.vertexLabel('store').
ifNotExists().
partitionBy('store_id', Int).
property('name', Text).
create()
// END-createVL_store
// MULTIPLE-KEY VERTEX ID
// START-createVL_meal
schema.vertexLabel('meal').
ifNotExists().
partitionBy('type', Text).
partitionBy( 'meal_id', Int).
create()
// END-createVL_meal
// COMPOSITE KEY VERTEX ID
// START-createVL_fridge_sensor
schema.vertexLabel('fridge_sensor').
ifNotExists().
partitionBy('state_id', Int).
partitionBy('city_id', Int).
partitionBy('zipcode_id', Int).
clusterBy('sensor_id', Int).
property('name', Text).
create()
// END-createVL_fridge_sensor
// GEOSPATIAL
// START-createVL_location
schema.vertexLabel('location').
ifNotExists().
partitionBy('loc_id', Text).
property('name', Text).
property('loc_details', frozen(typeOf('location_details'))).
property('geo_point', Point).
create()
// END-createVL_location
// STATIC COLUMN
// START-createVL_flag
schema.vertexLabel('flag').
ifNotExists().
partitionBy('country_id', Int).
clusterBy('country', Text).
property('flag', Text, Static).
create()
// END-createVL_flag
Each property must be defined with a valid CQL
data type. By default, properties have single cardinality, but
can be defined with multiple cardinality using collections. Multiple
cardinality allows more than one value to be assigned to a property.
In addition, properties can have their own properties using nested
collections such as listOf(tupleOf); in older versions
these properties were called meta-properties. Notice that vertex
labels can be created with ifNotExists(), to prevent
overwriting a definition that already exists.
CAUTION: DataStax Graph limits the number of vertex
and edge labels to 200 per graph.
Add property to a vertex label
The schema for vertex labels defines the label type, at least one
partition key, optional clustering columns, and properties. Additionally,
properties can be added later:
The schema for edge labels defines the label type, and defines the two
vertex labels that are connected by the edge label with
from() and to(). The
reviewed edge label defines edges between adjacent
vertices with the outgoing vertex label person and the
incoming vertex label recipe. By default, edges have single
cardinality. To specify multiple edges between two unique vertex labels, a
distinguishing edge property must be included in the edge label schema.
Add properties to vertex labels or edge labels
Alter the vertex label book by adding the property
book_discount:
The schema.describe() query displays schema that can be used to
recreate the schema entered or verify schema settings. Additional steps can display
the schema of all elements such as vertex labels, or the schema for a particular
element.
Procedure
Examine all the schema:
schema.describe()
In Studio, a portion of the output:The Gremlin console result:
Indexing is an important subject in DSG, because indexes are
a necessary component for successful completion of most graph queries in production
environments. The dev mode can be used to bypass the need for indexes
during development, but it is important to familiarize yourself with indexes.
Indexes can be created:
manually as materialized view indexes, secondary indexes, or search indexes
using the index analyzer indexFor() on desired graph queries
for the specialized case of bidirectional indexing, using
inverse()
Materialized view and secondary indexes are two types of indexes that use Cassandra
built-in indexing. Materialized views are good for queries that do not require
predicate-based searches. Secondary indexes allow indexing of properties stored in
collections. Search indexes use DSE Search which is Solr-based. Only one search index per
vertex label is allowed, but multiple properties can be included. Note that indexes are
manually added with create() for both vertex labels and edge labels. See
Creating index schema for complete examples of
each type of index.
Important: As with all queries in Graph, if you are
using Gremlin console, alias the graph traversal g to a graph with
:remote config alias g food_qs.g before running any
commands.
Procedure
Materialized view indexes
Discover a required materalized view index for the vertex label person
using the index analyzer steps indexFor() and
analyze():
==>Traversal requires that the following indexes are created:
schema.vertexLabel('person').materializedView('person_by_name').ifNotExists().partitionBy('name').clusterBy('person_id', Asc).create()
Create the required materalized view index for the vertex label person
using the index analyzer steps indexFor() and
apply():
Note
that the only change is switching apply() for analyze()
from the last step.
==>Creating the following indexes:
schema.vertexLabel('person').materializedView('person_by_name').ifNotExists().partitionBy('name').clusterBy('person_id', Asc).create()
OK
Materialized view indexes for vertex labels can also be made manually:
Discover a required materalized view index for the edge label
person->reviewed->recipe based on review star ratings
stars using the index analyzer steps indexFor() and
analyze():
==>Traversal requires that the following indexes are created:
schema.edgeLabel('reviewed').
from('person').to('recipe').
materializedView('person__reviewed__recipe_by_person_person_id_stars').
ifNotExists().
partitionBy(OUT, 'person_id').
partitionBy('stars').
clusterBy(IN, 'recipe_id', Asc).
create()
Create the required materalized view index for the edge label
person->reviewed->recipe by applying the index analyzer:
==>Creating the following indexes:
schema.edgeLabel('reviewed').from('person').to('recipe').materializedView('person__reviewed__recipe_by_person_person_id_stars').ifNotExists().partitionBy(OUT, 'person_id').partitionBy('stars').clusterBy(IN, 'recipe_id', Asc).create()
OK
Materialized view indexes for edge labels can be made manually:
In this case, the index is created to discover recipe reviews that occur before or
after a particular date.
Secondary indexes
Discover a required secondary index for the vertex label recipe based
on the cuisines stored in a collection of the recipe using the index analyzer steps
indexFor() and analyze():
==>Traversal requires that the following indexes are created:
schema.vertexLabel('recipe').secondaryIndex('recipe_2i_by_cuisine').ifNotExists().by('cuisine').indexValues().create()
Create the required secondary index for the vertex label recipe by
applying the index analyzer:
==>Creating the following indexes:
schema.vertexLabel('recipe').secondaryIndex('recipe_2i_by_cuisine').ifNotExists().by('cuisine').indexValues().create()
OK
Secondary indexes for vertex labels can be made manually:
Discover a search index for the vertex label recipe that requires a
tokenized search of the property instructions using the index analyzer
steps indexFor() and analyze():
Discover a required secondary index for the edge label
person->reviewed->recipe based on review star ratings
stars using the index analyzer steps indexFor() and
analyze():
Now that the schema is created, data may be added using either the traversal method
shown in the simple example or DataStax Bulk
Loader. The existing data can be dropped from the graph before
reloading.
Note the first commands drop all vertex and edge data from the graph,
g.V().drop() and g.E().drop(), to clear all
previously inserted data. In Studio, be sure to select the Graph
view after running the commands to verify the deletions.
Important: As with all queries in Graph, if you are
using Gremlin console, alias the graph traversal g to a graph with
:remote config alias g food_qs.g before running any
commands.
Procedure
Adding more data using
traversals
Drop the data previously loaded:
g.V().drop()
g.E().drop()
Load the vertices:
// START-insertAllPersons
// person vertices
g.addV('person').
property('person_id', 'e7cd5752-bc0d-4157-a80f-7523add8dbcd' as UUID).
property('name', 'Julia CHILD').
property('gender','F').
property('nickname', ['Jay', 'Julia'] as Set).
property('country', [['USA', '1912-08-12' as LocalDate, '1944-01-01' as LocalDate] as Tuple, ['Ceylon', '1944-01-01' as LocalDate, '1945-06-01' as LocalDate] as Tuple, ['France', '1948-01-01' as LocalDate, '1950-01-01' as LocalDate] as Tuple, ['USA', '1960-01-01' as LocalDate, '2004-08-13' as LocalDate] as Tuple]).
iterate();
g.addV('person').
property('person_id', 'adb8744c-d015-4d78-918a-d7f062c59e8f' as UUID).
property('name', 'Simone BECK').
property('gender','F').
property('nickname', ['Simca', 'Simone'] as Set).
property('country', [['France', '1904-07-07' as LocalDate, '1991-12-20' as LocalDate] as Tuple]).
iterate();
g.addV('person').
property('person_id', '888ad970-0efc-4e2c-b234-b6a71c30efb5' as UUID).
property('name', 'Fritz STREIFF').
property('gender','M').
iterate();
g.addV('person').
property('person_id', 'f092107c-0c5c-47e7-917c-c82c7fc2a2493' as UUID).
property('name', 'Louisette BERTHOLIE').
property('gender','F').
iterate();
g.addV('person').
property('person_id', 'ef811281-f954-4fd6-ace0-bf67d057771a' as UUID).
property('name', 'Patricia SIMON').
property('gender','F').
property('nickname', ['Pat'] as Set).
iterate();
g.addV('person').
property('person_id', 'd45c76bc-6f93-4d0e-9d9f-33298dae0524' as UUID).
property('name', 'Alice WATERS').
property('gender','F').
iterate();
g.addV('person').
property('person_id', '7f969e16-b81e-4fcd-87c5-1911abbed132' as UUID).
property('name', 'Patricia CURTAN').
property('gender','F').
property('nickname', ['Pattie'] as Set).
iterate();
g.addV('person').
property('person_id', '01e22ca6-da10-4cf7-8903-9b7e30c25805' as UUID).
property('name', 'Kelsie KERR').
property('gender','F').
iterate();
g.addV('person').
property('person_id', 'ad58b8bd-033f-48ee-8f3b-a84f9c24e7de' as UUID).
property('name', 'Emeril LAGASSE').
property('gender','M').
iterate();
g.addV('person').
property('person_id', '4ce9caf1-25b8-468e-a983-69bad20c017a' as UUID).
property('name', 'James BEARD').
property('gender','M').
property('nickname', ['Jim', 'Jimmy'] as Set).
iterate();
// END-insertAllPersons
// START-AllPersonReviewers
// reviewer vertices
g.addV('person').
property('person_id', '46ad98ac-f5c9-4411-815a-f81b3b667921' as UUID).
property('name', 'John DOE').
property('gender','M').
property('cal_goal', 1750).
property('macro_goal', [10,30,60]).
property('badge', ['silver':'2016-01-01' as LocalDate, 'gold':'2017-01-01' as LocalDate]).
iterate();
g.addV('person').
property('person_id', '4954d71d-f78c-4a6d-9c4a-f40903edbf3c' as UUID).
property('name', 'John SMITH').
property('gender','M').
property('nickname', ['Johnie'] as Set).
property('cal_goal', 1800).
property('macro_goal', [30,20,50]).
iterate();
g.addV('person').
property('person_id', '6c09f656-5aef-46df-97f9-e7f984c9a3d9' as UUID).
property('name', 'Jane DOE').
property('gender','F').
property('nickname', ['Janie'] as Set).
property('cal_goal', 1500).
property('macro_goal', [50,15,35]).
iterate();
g.addV('person').
property('person_id', 'daa02698-df4f-4436-8855-941774f4c3e0' as UUID).
property('name', 'Sharon SMITH').
property('gender','F').
property('cal_goal', 1600).
property('macro_goal', [30,20,50]).
iterate();
g.addV('person').
property('person_id', '6bda1b37-fe96-42bd-a2db-682073d10c37' as UUID).
property('name', 'Betsy JONES').
property('gender','F').
property('cal_goal', 1700).
property('macro_goal', [10,50,30]).
iterate();
// END-AllPersonReviewers
// START-insertAllBook
// book vertices
g.addV('book').
property('book_id',1001).
property('name','The Art of French Cooking, Vol. 1').
property('publish_year',1961).
property('category', ['French', 'general', 'cooking'] as Set).
iterate();
g.addV('book').
property('book_id', 1002).
property('name',"Simca's Cuisine: 100 Classic French Recipes for Every Occasion").
property('publish_year', 1972).
property('isbn', '0-394-40152-2').
property('category', ['French', 'cooking'] as Set).
iterate();
g.addV('book').
property('book_id', 1003).
property('name','The French Chef Cookbook').
property('publish_year', 1968).
property('isbn', '0-394-40135-2').
property('category', ['French', 'cooking'] as Set).
property('book_discount', '10%').
iterate();
g.addV('book').
property('book_id', 1004).
property('name', 'The Art of Simple Food: Notes, Lessons, and Recipes from a Delicious Revolution').
property('publish_year', 2007).
property('isbn', '0-307-33679-4').
property('category', ['American', 'cooking', 'simple'] as Set).
iterate();
// END-insertAllBook
//START-insertAllRecipe
// recipe vertices
g.addV('recipe').
property('recipe_id', 2001).
property('name', 'Beef Bourguignon').
property('cuisine', ['French', 'entree', 'beef'] as Set).
property('instructions', 'Braise the beef. Saute the onions and carrots. Add wine and cook in a dutch oven at 425 degrees for 1 hour.').
property('notes', 'Takes a long time to make.').
iterate();
g.addV('recipe').
property('recipe_id', 2002).
property('name', 'Rataouille').
property('instructions', 'Peel and cut the egglant. Make sure you cut eggplant into lengthwise slices that are about 1-inch wmyIde, 3-inches long, and 3/8-inch thick').
property('notes', "I've made this 13 times.").
iterate();
g.addV('recipe').
property('recipe_id', 2003).
property('name', 'Salade Nicoise').
property('instructions', 'Take a salad bowl or platter and line it with lettuce leaves, shortly before serving. Drizzle some olive oil on the leaves and dust them with salt.').
property('notes', '').
iterate();
g.addV('recipe').
property('recipe_id', 2004).
property('name', 'Wild Mushroom Stroganoff').
property('instructions', 'Cook the egg noodles according to the package directions and keep warm. Heat 1 1/2 tablespoons of the oliveoil in a large saute pan over medium-high heat.').
property('notes', 'Good for Jan and Bill.').
iterate();
g.addV('recipe').
property('recipe_id', 2005).
property('name', 'Spicy Meatloaf').
property('instructions', 'Preheat the oven to 375 degrees F. Cook bacon in a large skillet over medium heat until very crisp and fat has rendered, 8-10 minutes.').
property('notes', ' ').
iterate();
g.addV('recipe').
property('recipe_id', 2006) .
property('name', 'Oysters Rockefeller').
property('instructions', 'Saute the shallots, celery, herbs, and seasonings in 3 tablespoons of the butter for 3 minutes. Add the watercress and let it wilt.').
property('notes', ' ').
iterate();
g.addV('recipe').
property('recipe_id', 2007).
property('name', 'Carrot Soup') .
property('instructions', 'In a heavy-bottomed pot, melt the butter. When it starts to foam, add the onions and thyme and cook over medium-low heat until tender, about 10 minutes.').
property('notes', 'Quick and easy.').
iterate();
g.addV('recipe').
property('recipe_id', 2008).
property('name', 'Roast Pork Loin').
property('instructions', 'The day before, separate the meat from the ribs, stopping about 1 inch before the end of the bones. Season the pork liberally inside and out with salt and pepper and refrigerate overnight.').
property('notes', 'Love this one!').
iterate();
//END-insertAllRecipe
// START-insertAllIngred
// ingredients vertices
g.addV('ingredient').
property('ingred_id', 3001).
property('name', 'beef').
iterate();
g.addV('ingredient').
property('ingred_id', 3002).
property('name', 'onion').
iterate();
g.addV('ingredient').
property('ingred_id', 3003).
property('name', 'mashed garlic').
iterate();
g.addV('ingredient').
property('ingred_id', 3004).
property('name', 'butter').
iterate();
g.addV('ingredient').
property('ingred_id', 3005).
property('name', 'tomato paste').
iterate();
g.addV('ingredient').
property('ingred_id', 3006).
property('name', 'eggplant').
iterate();
g.addV('ingredient').
property('ingred_id', 3007).
property('name', 'zucchini').
iterate();
g.addV('ingredient').
property('ingred_id', 3008).
property('name', 'olive oil').
iterate();
g.addV('ingredient').
property('ingred_id', 3009).
property('name', 'yellow onion').
iterate();
g.addV('ingredient').
property('ingred_id', 3010).
property('name', 'green beans').
iterate();
g.addV('ingredient').
property('ingred_id', 3011).
property('name', 'tuna').
iterate();
g.addV('ingredient').
property('ingred_id', 3012).
property('name', 'tomato').
iterate();
g.addV('ingredient').
property('ingred_id', 3013).
property('name', 'hard-boiled egg').
iterate();
g.addV('ingredient').
property('ingred_id', 3014).
property('name', 'egg noodles').
iterate();
g.addV('ingredient').
property('ingred_id', 3015).
property('name', 'mushrooms').
iterate();
g.addV('ingredient').
property('ingred_id', 3016).
property('name', 'bacon').
iterate();
g.addV('ingredient').
property('ingred_id', 3017).
property('name', 'celery').
iterate();
g.addV('ingredient').
property('ingred_id', 3018).
property('name', 'green bell pepper').
iterate();
g.addV('ingredient').
property('ingred_id', 3019).
property('name', 'ground beef').
iterate();
g.addV('ingredient').
property('ingred_id', 3020).
property('name', 'pork sausage').
iterate();
g.addV('ingredient').
property('ingred_id', 3021).
property('name', 'shallots').
iterate();
g.addV('ingredient').
property('ingred_id', 3022).
property('name', 'chervil').
iterate();
g.addV('ingredient').
property('ingred_id', 3023).
property('name', 'fennel').
iterate();
g.addV('ingredient').
property('ingred_id', 3024).
property('name', 'parsley').
iterate();
g.addV('ingredient').
property('ingred_id', 3025).
property('name', 'oyster').
iterate();
g.addV('ingredient').
property('ingred_id', 3026).
property('name', 'Pernod').
iterate();
g.addV('ingredient').
property('ingred_id', 3027).
property('name', 'thyme').
iterate();
g.addV('ingredient').
property('ingred_id', 3028).
property('name', 'carrots').
iterate();
g.addV('ingredient').
property('ingred_id', 3029).
property('name', 'chicken broth').
iterate();
g.addV('ingredient').
property('ingred_id', 3030).
property('name', 'pork loin').
iterate();
g.addV('ingredient').
property('ingred_id', 3031).
property('name', 'red wine').
iterate();
// END-insertAllIngred
// START-insertAllMeals
// Insert meal vertices
g.addV('meal').
property('meal_id', 4001).
property('type', 'lunch').
iterate();
g.addV('meal').
property('meal_id', 4002).
property('type', 'lunch').
iterate();
g.addV('meal').
property('meal_id', 4003).
property('type', 'lunch').
iterate();
g.addV('meal').
property('meal_id', 4004).
property('type', 'lunch').
iterate();
g.addV('meal').
property('meal_id', 4005).
property('type', 'breakfast').
iterate();
g.addV('meal').
property('meal_id', 4006).
property('type', 'snack').
iterate();
g.addV('meal').
property('meal_id', 4007).
property('type', 'dinner').
iterate();
g.addV('meal').
property('meal_id', 4008).
property('type', 'dinner').
iterate();
// END-insertAllMeals
// START-insertAllMealitems
// meal_items
g.addV('meal_item').
property('item_id',5001).
property('name','taco').
property('serv_amt', '1').
property('macro',[15,65,65]).
property('calories',650).
iterate();
g.addV('meal_item').
property('item_id',5002).
property('name','burrito').
property('serv_amt', '1').
property('macro',[15,65,65]).
property('calories',1230).
iterate();
g.addV('meal_item').
property('item_id',5003).
property('name','iced tea').
property('serv_amt', '2 cups').
property('macro',[0,0,0]).
property('calories',0).
iterate();
// END-insertAllMealitems
// START-insertAllFridge_sensor
// fridge_sensor vertices
g.addV('fridge_sensor').
property('state_id', 31).
property('city_id', 100).
property('zipcode_id', 55555).
property('sensor_id', 001).
iterate();
g.addV('fridge_sensor').
property('state_id', 31).
property('city_id', 100).
property('zipcode_id', 55555).
property('sensor_id', 002).
iterate();
g.addV('fridge_sensor').
property('state_id', 31).
property('city_id', 100).
property('zipcode_id', 55555).
property('sensor_id', 003).
iterate();
g.addV('fridge_sensor').
property('state_id', 31).
property('city_id', 200).
property('zipcode_id', 55556).
property('sensor_id', 001).
iterate();
g.addV('fridge_sensor').
property('state_id', 31).
property('city_id', 200).
property('zipcode_id', 55556).
property('sensor_id', 002).
iterate();
g.addV('fridge_sensor').
property('state_id', 31).
property('city_id', 200).
property('zipcode_id', 55556).
property('sensor_id', 003).
iterate();
g.addV('fridge_sensor').
property('state_id', 45).
property('city_id', 300).
property('zipcode_id', 66665).
property('sensor_id', 001).
iterate();
g.addV('fridge_sensor').
property('state_id', 45).
property('city_id', 300).
property('zipcode_id', 66665).
property('sensor_id', 002).
iterate();
g.addV('fridge_sensor').
property('state_id', 45).
property('city_id', 300).
property('zipcode_id', 66665).
property('sensor_id', 003).
iterate();
// END-insertAllFridge_sensor
// START-insertAllLocation
// Insert location data
g.addV('location').
property('loc_id', 'g1').
property('name', 'Paris').
property('geo_point', 'POINT (2.352222 48.856614)' as Point).
iterate();
g.addV('location').
property('loc_id', 'g2').
property('name', 'London').
property('geo_point', 'POINT (-0.127758 51.507351)' as Point).
iterate();
g.addV('location').
property('loc_id', 'g3').
property('name', 'Dublin').
property('geo_point', 'POINT (-6.26031 53.349805)' as Point).
iterate();
g.addV('location').
property('loc_id', 'g4').
property('name', 'Aachen').
property('geo_point', 'POINT (6.083887 50.775346)' as Point).
iterate();
g.addV('location').
property('loc_id', 'g5').
property('name', 'Tokyo').
property('geo_point', 'POINT (139.691706 35.689487)' as Point).
iterate();
g.addV('location').
property('loc_id', 'g5').
property('name', 'Tokyo').
property('geo_point', 'POINT (139.691706 35.689487)' as Point).
iterate();
g.addV('location').
property('loc_id', 'g6').
property('name', 'New York').
property('geo_point', 'POINT (74.0059 40.7128)' as Point).
iterate();
g.addV('location').
property('loc_id', 'g7').
property('name', 'New Orleans').
property('geo_point', 'POINT (90.0715 29.9511)' as Point).
iterate();
g.addV('location').
property('loc_id', 'g8').
property('name', 'Los Angeles').
property('geo_point', 'POINT (118.2437 34.0522)' as Point).
iterate();
g.addV('location').
property('loc_id', 'g9').
property('name', 'Chicago').
property('geo_point', 'POINT (-87.6298 41.8781136)' as Point).
iterate();
g.addV('location').
property('loc_id', 'g10').
property('name', "Jane's house").
property('geo_point', 'POINT (118.5 34.0000)' as Point).
iterate();
g.addV('location').
property('loc_id', 'g11').
property('name', "John Smith's place").
property('geo_point', 'POINT (90.0000 30.000)' as Point).
iterate();
g.addV('location').
property('loc_id', 'g12').
property('name', "Mary's house").
property('loc_details', [ loc_address: [address1:'215 1st St', city_code:'Winston', state_code:'CA', zip_code:'93002'] as address, telephone: ['530-555-1255', '916-442-2211'] ] as location_details).
property('geo_point', 'POINT(-106.372802 35.107546)' as Point).
iterate();
g.addV('location').
property('loc_id', 'g13').
property('name', 'Zippy Mart').
property('loc_details', [ loc_address: [address1:'213 F St', city_code:'Winston', state_code:'CA', zip_code:'93001'] as address, telephone: ['530-555-3455', '916-446-2211'] ] as location_details).
property('geo_point', 'POINT(-112.347309 34.622238)' as Point).
iterate();
g.addV('location').
property('loc_id', 'g14').
property('name', 'Quik Station').
property('loc_details', [ loc_address: [address1:'500 C St', city_code:'Winston', state_code:'CA', zip_code:'93001'] as address, telephone: ['530-555-3454', '916-446-1111'] ] as location_details).
property('geo_point', 'POINT(-74.575156 39.339838)' as Point).
iterate();
g.addV('location').
property('loc_id', 'g15').
property('name', "Mamma's Grocery").
property('loc_details', [ loc_address: [address1:'1000 A St', city_code:'Winston', state_code:'CA', zip_code:'93001'] as address, telephone: ['530-555-1212', '916-444-3454'] ] as location_details).
property('geo_point', 'POINT(-74.423251 42.323255)' as Point).
iterate();
g.addV('location').
property('loc_id', 'g100').
property('name', 'test location').
property('loc_details', [ loc_address: [address1:'757 Jay St', city_code:'Arbuckle', state_code:'CA', zip_code:'95691'] as address, telephone: ['530-555-1212', '916-4444-3454'] ] as location_details).
property('geo_point', 'POINT (1.352222 48.856614)' as Point).
iterate();
// END-insertAllLocation
// START-insertAllHome
// Insert home data
g.addV('home').
property('home_id', 9000).
property('name', "Jane's house").
iterate();
g.addV('home').
property('home_id', 9001).
property('name', "John Smith's place").
iterate();
g.addV('home').
property('home_id', 9002).
property('name', "Mary's house").
iterate();
// END-insertAllHome
//START-insertAllStore
// Insert all store vertices
g.addV('store').
property('store_id', 8001).
property('name', 'Zippy Mart').
iterate();
g.addV('store').
property('store_id', 8002).
property('name', 'Quik Station').
iterate();
g.addV('store').
property('store_id', 8003).
property('name', "Mamma's Grocery").
iterate();
//END-insertAllStore
Load the edges. Studio does have a limitation on the number of commands
executed in each cell due to serialization to bytecode. To accommodate that
limitation, load the following edges in batches in separate cells. Gremlin
console does not have the same limitation, so load all edges as shown.
In Studio, run the following command to display all the data:
dev.with('label-warning', false).V()
and additionally, if using Gremlin console, run the following command to see the
edges:
dev.with('label-warning', false).E()
Studio
will display both vertices and edges when the vertices are queried.
Figure 2: Data for the Food Graph
In Gremlin console, run the following commands to view the results, similar
to the sample shown here:
// A series of returns for vertices and edges will mark the successful completion
gremlin> dev.V()
==>v[dseg:/person/4ce9caf1-25b8-468e-a983-69bad20c017a]
==>v[dseg:/person/888ad970-0efc-4e2c-b234-b6a71c30efb5]
==>v[dseg:/person/4954d71d-f78c-4a6d-9c4a-f40903edbf3c]
==>v[dseg:/person/01e22ca6-da10-4cf7-8903-9b7e30c25805]
==>v[dseg:/person/6c09f656-5aef-46df-97f9-e7f984c9a3d9]
==>v[dseg:/person/daa02698-df4f-4436-8855-941774f4c3e0]
==>v[dseg:/person/d45c76bc-6f93-4d0e-9d9f-33298dae0524]
==>v[dseg:/person/adb8744c-d015-4d78-918a-d7f062c59e8f]
==>v[dseg:/person/e7cd5752-bc0d-4157-a80f-7523add8dbcd]
==>v[dseg:/person/f092107c-0c5c-47e7-917c-82c7fc2a2493]
==>v[dseg:/person/ad58b8bd-033f-48ee-8f3b-a84f9c24e7de]
==>v[dseg:/person/6bda1b37-fe96-42bd-a2db-682073d10c37]
==>v[dseg:/person/7f969e16-b81e-4fcd-87c5-1911abbed132]
==>v[dseg:/person/ef811281-f954-4fd6-ace0-bf67d057771a]
==>v[dseg:/person/46ad98ac-f5c9-4411-815a-f81b3b667921]
==>v[dseg:/book/1001]
==>v[dseg:/book/1002]
gremlin> dev.E()
==>e[dseg:/person-authored-book/adb8744c-d015-4d78-918a-d7f062c59e8f/1001][dseg:/person/adb8744c-d015-4d78-918a-d7f062c59e8f-authored->dseg:/book/1001]
==>e[dseg:/person-authored-book/adb8744c-d015-4d78-918a-d7f062c59e8f/1002][dseg:/person/adb8744c-d015-4d78-918a-d7f062c59e8f-authored->dseg:/book/1002]
==>e[dseg:/person-authored-book/e7cd5752-bc0d-4157-a80f-7523add8dbcd/1001][dseg:/person/e7cd5752-bc0d-4157-a80f-7523add8dbcd-authored->dseg:/book/1001]
==>e[dseg:/person-authored-book/ef811281-f954-4fd6-ace0-bf67d057771a/1002][dseg:/person/ef811281-f954-4fd6-ace0-bf67d057771a-authored->dseg:/book/1002]
==>e[dseg:/person-knows-person/e7cd5752-bc0d-4157-a80f-7523add8dbcd/adb8744c-d015-4d78-918a-d7f062c59e8f][dseg:/person/e7cd5752-bc0d-4157-a80f-7523add8dbcd-knows->dseg:/person/adb8744c-d015-4d78-918a-d7f062c59e8f]
If a vertex count is run, there is now a higher count of 100 vertices. Run the
vertex count again:
g.V().count()
Similarly, the edge count can be run, to discover the higher edge count of
112:
g.E().count()
Adding more data using the DataStax Bulk Loader
(optional)
Data can be loaded with DataStax Bulk
Loader, a standalone command-line tool, using CSV or JSON input files
(see the next cell for CSV files that will be loaded). The following commands
should be run from a terminal on a cluster node that has dsbulk
installed.
Load data to person table from a CSV file with a pipe
delimiter and allow missing field values:
CSV data file located in data/vertices/person.csv
containing:
Load data to book table from a CSV file with a pipe
delimiter, allow missing field values, and identifying the
field->columns with schema mapping:
CSV data file located in data/vertices/book.csv
containing:
book_id|name|publish_year|isbn
1001|The Art of French Cooking, Vol. 1|1961|
1002|Simca's Cuisine: 100 Classic French Recipes for Every Occasion|1972|0-394-40152-2
1003|The French Chef Cookbook|1968|0-394-40135-2
1004|The Art of Simple Food: Notes, Lessons, and Recipes from a Delicious Revolution|2007|0-307-33679-4
Load data to person_authored_book table from a CSV file with
a pipe delimiter, allow missing field values, and map CSV file positions to
named columns in the table:
CSV data file located in
data/edges/person_authored_book.csv
containing:
DataStax Bulk Loader is very versatile, and should be explored in its
entirety.
QuickStart Exploring traversals
Explore graph data with query traversals.
Exploring the graph with graph traversals can lead to interesting conclusions. Here we'll
explore a number of traversals, to show off the power of Gremlin in creating simple
queries.
Important: As with all queries in Graph, if you are
using Gremlin console, alias the graph traversal g to a graph with
:remote config alias g food_qs.g before running any
commands.
Procedure
All queries can be profiled to see what the query path is and how the query performs. The
profile() step will display information abut the length of time each portion
of the command takes to run, as well as the underlying CQL command that is run to complete the
Gremlin command.
In all the following queries, to investigate what happens, and why some queries are more
efficient than others, try adding .profile() to any query will show you information
similar to the information above.
Graph queries will have lower latency if the query is more specific, and uses the
has() step is for narrowing the search. Compare the following queries and
their profiles (by adding .profile() to the end:
Running any of these queries in Studio will display the vertex id, label and all property
values. In Gremlin console, these queries will only display the vertex id; the
elementMap() step must be appended to get the property values.
In this next traversal, has() filters vertex properties by name =
Julia Child as seen above. The traversal step outE() discovers the
outgoing edges from that vertex with the authored label.
If instead, you want to query for the books that all people have written, the query must be
modified. The previous example retrieved edges, but not the adjacent book vertices. Add a
traversal step inV() to find all the vertices that connect to the outgoing
edges, then print the book titles of those vertices. Notice how the chained traversal steps go
from the vertices along outgoing edges to the adjacent vertices with
V().outE().inV(). The outgoing edges are given a particular filter value,
authored.
g.V().outE('authored').inV().values('name')
In Studio:
and in Gremlin
console:
==>The Art of Simple Food: Notes, Lessons, and Recipes from a Delicious Revolution
==>The Art of Simple Food: Notes, Lessons, and Recipes from a Delicious Revolution
==>The Art of Simple Food: Notes, Lessons, and Recipes from a Delicious Revolution
==>The Art of Simple Food: Notes, Lessons, and Recipes from a Delicious Revolution
==>The Art of French Cooking, Vol. 1
==>The Art of French Cooking, Vol. 1
==>Simca's Cuisine: 100 Classic French Recipes for Every Occasion
==>Simca's Cuisine: 100 Classic French Recipes for Every Occasion
==>The French Chef Cookbook
Notice that the book titles are duplicated in the resulting list, because a listing is
returned for each author. If a book has three authors, three listings are returned. The
traversal step dedup() can eliminate the duplication.
==>The Art of Simple Food: Notes, Lessons, and Recipes from a Delicious Revolution
==>The Art of French Cooking, Vol. 1
==>Simca's Cuisine: 100 Classic French Recipes for Every Occasion
==>The French Chef Cookbook
Refine the traversal by reinserting the has() step for a particular
author. Find all the books authored by Julia Child.
==>The Art of French Cooking, Vol. 1
==>The French Chef Cookbook
The previous example and this example accomplish the same result. However, the number of
traversal steps and the type of traversal steps can affect performance. The traversal step
outE() should be only used if the edges are explicitly required. In this
example, the edges are traversed to get information about connected vertices, but the edge
information is not important to the query.
==>The Art of French Cooking, Vol. 1
==>The French Chef Cookbook
The traversal step out() retrieves the connected book vertices based on the
edge label authored without retrieving the edge information. In a larger
graph traversal, this subtle difference in the traversal can become a latency issue.
Additional traversal steps continue to fine-tune the results. Adding another chained
has traversal step finds only books authored by Julia Child published after
1967. This example also displays the use of the gt, or greater than
function.
When developing or testing, oftentimes checking the number of vertices with each vertex
label can confirm that data was read. To find the number of vertices by vertex label, use the
traversal step label() followed by the traversal step
groupCount(). The step groupCount() is useful for
aggregating results from a previous step. Suppress the warning by prepending
g.with("label-warning", false). instead of g.:
Read your data from an output file to exchange information using the GraphSON
format:
g.io("/tmp/food_qs.json").read()
In Studio:
QuickStart Listing graphs
How to list graphs.
Discover information about all the graphs on a cluster with the
system commands.
Important: As with all queries in Graph, if you are
using Gremlin console, alias the graph traversal g to a graph with
:remote config alias g food_qs.g before running any
commands.
Procedure
To discover all graphs that exist, use a system command:
system.graphs()
In Studio: In Gremlin
console:
==>food_qs
To discover information about all the graphs that exist:
Schema can be modified after creation, adding properties with
addProperty() and alter() and dropping any
element, property, vertex label, edge label, or index with drop().
Edge label alterations can additionally specify the pair of vertex labels on which
the modification is accomplished. The data type of a property, however, cannot be
changed, without removing and recreating the property.
In addition, metadata about the vertex labels and edge labels can be dropped. If a
vertex label's metadata is dropped, the underlying table remains, but the label is
removed along with any associated edge tables. Similarly, if an edge label's
metadata is dropped, the underlying edge label tables remain, but the connections to
any vertex labels are dropped. Dropping all metadata removes all vertex labels and
edge labels, but the underlying CQL tables remain, but are not associated with the
graph.
The latter variation is useful when an edge label is defined between more
than one set of vertex labels. For instance, if both
person->authored->book and
person->authored->blog existed, then the expanded
command would only drop the properties from
person->authored->book.
Tip: In Studio, the result can be displayed using different views: Raw JSON, Table, or Graph. Explore the options.The Gremlin console result:
The Gremlin console result:
CAUTION: UsingIn Gremlin console:
In Gremlin console, run the following commands to view the results, similar to the sample shown here:
In Gremlin console:
In Gremlin console:
and in Gremlin
console:
and in Gremlin
console:
and in Gremlin
console:
and in Gremlin
console:
and in Gremlin
console:
