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Deploy Raft Listener for Nebula Storage service

Full-Text index data is written to the Elasticsearch cluster asynchronously. The Raft Listener (hereinafter shortened as Listener) is a separate process that fetches data from the Storage Service and writes them into the Elasticsearch cluster.

Prerequisites

  • You have read and fully understand the restrictions for using Full-Text indexes.
  • You have prepared at least one extra Storage Server. To use the Full-Text search, you must run one or more Storage Server as the Raft Listener.

Precautions

  • The Storage Service that you want to run as a Listener must have the same or later version with all the other Nebula Graph services in the cluster.
  • For now, you can only add Listeners to a graph space once and for all. Trying to add listeners to a graph space that already has a listener will fail. To add multiple listeners, set them in one statement.

Step 1: Prepare the configuration file for the Listeners

You have to prepare a Listener configuration file on the machine that you want to deploy the Listeners. The file name must be nebula-storaged-listener.conf. A template is provided for your reference.

NOTE: Use real IP addresses in the configuration file instead of domain names or loopback IP addresses such as 127.0.0.1.

Step 2: Start the Listeners

Run the following command to start the Listeners.

./bin/nebula-storaged --flagfile ${listener_config_path}/nebula-storaged-listener.conf

${listener_config_path} is the path where you store the Listener configuration file.

Step 3: Add Listeners to Nebula Graph

Connect to Nebula Graph and run USE <space> to enter the graph space that you want to create Full-Text indexes for. Then run the following statement to add the Listener into Nebula Graph.

NOTE: You must use real IPs for the listeners.

ADD LISTENER ELASTICSEARCH <listener_ip:port> [,<listener_ip:port>, ...]

Multiple listener_ip:port pairs are separated with commas. For example:

nebula> ADD LISTENER ELASTICSEARCH 192.168.8.5:46780,192.168.8.6:46780;

Show Listeners

Run the SHOW LISTENER statement to list the Listeners.

For example:

nebula> SHOW LISTENER;
+--------+-----------------+-----------------------+----------+
| PartId | Type            | Host                  | Status   |
+--------+-----------------+-----------------------+----------+
| 1      | "ELASTICSEARCH" | "[192.168.8.5:46780]" | "ONLINE" |
+--------+-----------------+-----------------------+----------+
| 2      | "ELASTICSEARCH" | "[192.168.8.5:46780]" | "ONLINE" |
+--------+-----------------+-----------------------+----------+
| 3      | "ELASTICSEARCH" | "[192.168.8.5:46780]" | "ONLINE" |
+--------+-----------------+-----------------------+----------+

Remove Listeners

Run the REMOVE LISTENER ELASTICSEARCH statement to remove all the Elasticsearch Listeners for a graph space.

For example:

nebula> REMOVE LISTENER ELASTICSEARCH;

What to do next

After deploying the Elasticsearch cluster and the Listeners, Full-Text indexes are created automatically on the Elasticsearch cluster. You can do Full-Text search now. For more information, see Full-Text search.

Last update: April 1, 2021
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