To understand why an index cannot be important as a dangling index because another with the same name already exisits in the cluster metadata, we commend you run this Elasticsearch Error Check-Up which can help you resolve the issue and prevent others from occuring.
This guide will help you check for common problems that cause the log “Cannot be imported as a dangling index, as index with same name already exists in cluster metadata” 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: cluster, dangling, index, indices and metadata.
quick Overview
When you get this log it means that a cluster is trying to import a stale index.
How to solve:
1. Call GET _cat/indices?v and find UUID column. These UUIDs should match directory names inside node data path under “nodes/0/indices”. Otherwise, these directories are dangling indices. That the node is trying to import.
2. For every dangling index, you can move them out of this nodes/0/indices into the same directory structure of a new Elasticsearch node installation. This will result in having two nodes. You can decide which node you want to keep.
Overview
In Elasticsearch, an index (plural: indices) contains a schema and can have one or more shards and replicas. An Elasticsearch index is divided into shards and each shard is an instance of a Lucene index.
Indices are used to store the documents in dedicated data structures corresponding to the data type of fields. For example, text fields are stored inside an inverted index whereas numeric and geo fields are stored inside BKD trees.
Examples
Create index
The following example is based on Elasticsearch version 5.x onwards. An index with two shards, each having one replica will be created with the name test_index1
PUT /test_index1?pretty
{
"settings" : {
"number_of_shards" : 2,
"number_of_replicas" : 1
},
"mappings" : {
"properties" : {
"tags" : { "type" : "keyword" },
"updated_at" : { "type" : "date" }
}
}
}List indices
All the index names and their basic information can be retrieved using the following command:
GET _cat/indices?v
Index a document
Let’s add a document in the index with the command below:
PUT test_index1/_doc/1
{
"tags": [
"opster",
"elasticsearch"
],
"date": "01-01-2020"
}Query an index
GET test_index1/_search
{
"query": {
"match_all": {}
}
}Query multiple indices
It is possible to search multiple indices with a single request. If it is a raw HTTP request, index names should be sent in comma-separated format, as shown in the example below, and in the case of a query via a programming language client such as python or Java, index names are to be sent in a list format.
GET test_index1,test_index2/_search
Delete indices
DELETE test_index1
Common problems
- It is good practice to define the settings and mapping of an Index wherever possible because if this is not done, Elasticsearch tries to automatically guess the data type of fields at the time of indexing. This automatic process may have disadvantages, such as mapping conflicts, duplicate data and incorrect data types being set in the index. If the fields are not known in advance, it’s better to use dynamic index templates.
- Elasticsearch supports wildcard patterns in Index names, which sometimes aids with querying multiple indices, but can also be very destructive too. For example, It is possible to delete all the indices in a single command using the following commands:
DELETE /*
To disable this, you can add the following lines in the elasticsearch.yml:
action.destructive_requires_name: true
Log Context
Log “[{}] can not be imported as a dangling index; as index with same name already exists in cluster metadata” classname is DanglingIndicesState.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
final ListindexMetaDataList = metaStateService.loadIndicesStates(excludeIndexPathIds::contains); Map newIndices = new HashMap(indexMetaDataList.size()); final IndexGraveyard graveyard = metaData.indexGraveyard(); for (IndexMetaData indexMetaData : indexMetaDataList) { if (metaData.hasIndex(indexMetaData.getIndex().getName())) { logger.warn("[{}] can not be imported as a dangling index; as index with same name already exists in cluster metadata"; indexMetaData.getIndex()); } else if (graveyard.containsIndex(indexMetaData.getIndex())) { logger.warn("[{}] can not be imported as a dangling index; as an index with the same name and UUID exist in the " + "index tombstones. This situation is likely caused by copying over the data directory for an index " + "that was previously deleted."; indexMetaData.getIndex());
