Index JanusGraph Database
Lifecycle
States (SchemaStatus)
| States | Description |
|---|---|
| INSTALLED | The index is installed in the system but not yet registered with all instances in the cluster |
| REGISTERED | The index is registered with all instances in the cluster but not (yet) enabled |
| ENABLED | The index is enabled and in use |
| DISABLED | The index is disabled and no longer in use |
Actions (SchemaAction)
| SchemaAction | Description |
|---|---|
| REGISTER_INDEX | Registers the index with all instances in the graph cluster. After an index is installed, it must be registered with all graph instances |
| REINDEX | Re-builds the index from the graph |
| ENABLE_INDEX | Enables the index so that it can be used by the query processing engine. An index must be registered before it can be enabled. |
| DISABLE_INDEX | Disables the index in the graph so that it is no longer used. |
| REMOVE_INDEX | Removes the index from the graph (optional operation). Only on composite index. |
Scripts to index the graph database
First you have to kill the gremlin server and change some parameters in the server script
ps aux | grep gremlin # finds the gramlin process id
sudo kill -9 8532
vi conf/gremlin-server/gremlin-server.yaml
# then change scriptEvaluationTimeout -> scriptEvaluationTimeout: 300000
# save and exit
# run the gramlin server again
cd janusgraph-0.4.0-hadoop2 # change directory to JanusGraph download location
sudo bin/gremlin-server.sh conf/gremlin-server/gremlin-server.yaml &
# make sure to run the command with & sign so that you can exit from the the command without killing it
Login to the gremlin console after restarting the server
sudo ./bin/gremlin.sh
# run inside the console to connect with the remote gremlin server
:remote connect tinkerpop.server conf/remote.yaml session
:remote console
Let’s assume the database is empty. Now we have to first create a node for indexing. Let’s create an account node
g.addV('Account').property(single, 'id', '11111111').next()
g.tx().commit()
Check for open transactions and close them
graph.getOpenTransactions()
// to remove any open transactions <- remove all open transactions by repeating the command
graph.getOpenTransactions().getAt(0).rollback()
Check for any open sessions and close them
mgmt = graph.openManagement()
mgmt.getOpenInstances()
// close all instances except the current instance
mgmt.forceCloseInstance('<_id_>')
mgmt.commit()
Printing schemas – this helps to view the internal organization of the database
mgmt = graph.openManagement()
mgmt.printSchema()
mgmt.commit()
Now let’s register the index with the graph. This commands adds an index with both the vertex label and a key property
graph.tx().rollback() //Never create new indexes while a transaction is active
mgmt = graph.openManagement()
accountId = mgmt.getPropertyKey('id')
account = mgmt.getVertexLabel('Account')
mgmt.buildIndex('byAccountIdAndLabel', Vertex.class).addKey(accountId).indexOnly(account).buildCompositeIndex()
mgmt.commit()
Now if you look at the schemas, you will see a Vertex Index Name by ‘byAccountIdAndLabel’ in the REGISTERED state
//Wait for the index to become available
ManagementSystem.awaitGraphIndexStatus(graph, 'byAccountIdAndLabel').call()
As the final step reindex the data in the graph
//Reindex the existing data
mgmt = graph.openManagement()
mgmt.updateIndex(mgmt.getGraphIndex("byAccountIdAndLabel"), SchemaAction.REINDEX).get()
mgmt.commit()
Now if you do a print schema command, you will see that the ‘byAccountIdAndLabel’ index status is turned to ENABLED
Troubleshooting
If you are unsuccessful in executing this procedure due to some interruption and the index gets stuck at the INSTALLED state there is a workaround to ENABLE the index
//Step1: Clear all transactions
graph.getOpenTransactions()
graph.getOpenTransactions().getAt(0).rollback()
//Step2: Clear all management instances
mgmt=graph.openManagement()
mgmt.getOpenInstances()
//After doing step 1 and 2
//Step3: Force change from Installed to Registered
mgmt = graph.openManagement()
mgmt.updateIndex(mgmt.getGraphIndex("byAccountIdAndLabel"), SchemaAction.REGISTER_INDEX).get()
mgmt.commit()
//Wait for the index to become available
ManagementSystem.awaitGraphIndexStatus(graph, 'byAccountIdAndLabel').call()
//Reindex the existing data
mgmt = graph.openManagement()
mgmt.updateIndex(mgmt.getGraphIndex("byAccountIdAndLabel"), SchemaAction.REINDEX).get()
mgmt.commit()
References
- https://docs.janusgraph.org/index-management/index-performance/
- https://groups.google.com/forum/#!topic/janusgraph-users/E0speKxetgM