To understand why your data has been deleted and to control this action in the future, you should run the Elasticsearch Error Check-Up. 29% of people who ran the Check-Up had this issue and the tool will help you configure your system to ensure optimal settings and performance for your use case.
This guide will help you check for common problems that cause the log “Deleting expired data” to appear. It’s important to understand the issues related to the log, so to get started, read the general overview on common issues and tips related to the Elasticsearch concepts: delete and plugin.
What this error means
This log message is an INFO message letting you know that all job results, model snapshots and forecast data that have exceeded their retention days period have been deleted.
Explanation
The “delete expired data” API comes as part of the X-Pack and is used to delete expired and unused machine learning data.
DELETE _ml/_delete_expired_data
The response is:
{
"deleted": true
}
When the “delete expired data” API is hit, the following log will be generated:
[INFO ][o.e.x.m.a.TransportDeleteExpiredDataAction] Deleting expired data [INFO ][o.e.x.m.a.TransportDeleteExpiredDataAction] Completed deletion of expired ML data
Overview
DELETE is an Elasticsearch API which removes a document from a specific index. This API requires an index name and _id document to delete the document.
Delete a document
DELETE /my_index/_doc/1
Notes
- A delete request throws 404 error code if the document does not already exist in the index.
- If you want to delete a set of documents that matches a query, you need to use delete by query API.
Overview
A plugin is used to enhance the core functionalities of Elasticsearch. Elasticsearch provides some core plugins as a part of their release installation. In addition to those core plugins, it is possible to write your own custom plugins as well. There are several community plugins available on GitHub for various use cases.
Examples
Get all of the instructions for the plugin:
sudo bin/elasticsearch-plugin -h
Installing the S3 plugin for storing Elasticsearch snapshots on S3:
sudo bin/elasticsearch-plugin install repository-s3
Removing a plugin:
sudo bin/elasticsearch-plugin remove repository-s3
Installing a plugin using the file’s path:
sudo bin/elasticsearch-plugin install file:///path/to/plugin.zip
Notes and good things to know
- Plugins are installed and removed using the elasticsearch-plugin script, which ships as a part of the Elasticsearch installation and can be found inside the bin/ directory of the Elasticsearch installation path.
- A plugin has to be installed on every node of the cluster and each of the nodes has to be restarted to make the plugin visible.
- You can also download the plugin manually and then install it using the elasticsearch-plugin install command, providing the file name/path of the plugin’s source file.
- When a plugin is removed, you will need to restart every Elasticsearch node in order to complete the removal process.
Common issues
- Managing permission issues during and after plugin installation is the most common problem. If Elasticsearch was installed using the DEB or RPM packages then the plugin has to be installed using the root user. Otherwise you can install the plugin as the user that owns all of the Elasticsearch files.
- In the case of DEB or RPM package installation, it is important to check the permissions of the plugins directory after you install it. You can update the permission if it has been modified using the following command:
chown -R elasticsearch:elasticsearch path_to_plugin_directory
- If your Elasticsearch nodes are running in a private subnet without internet access, you cannot install a plugin directly. In this case, you can simply download the plugins and copy the files inside the plugins directory of the Elasticsearch installation path on every node. The node has to be restarted in this case as well.
Log Context
Log “Deleting expired data” classname is TransportDeleteExpiredDataAction.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
this.clock = clock;
}
Override
protected void doExecute(DeleteExpiredDataAction.Request request; ActionListener listener) {
logger.info("Deleting expired data");
Instant timeoutTime = Instant.now(clock).plus(MAX_DURATION);
Supplier isTimedOutSupplier = () -> Instant.now(clock).isAfter(timeoutTime);
threadPool.executor(MachineLearning.UTILITY_THREAD_POOL_NAME).execute(() -> deleteExpiredData(listener; isTimedOutSupplier));
}
