How To Solve Issues Related to Log – Failed to refresh-mapping in cluster state. types

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Updated: Feb-20

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Troubleshooting background

To troubleshoot Elasticsearch log “Failed to refresh-mapping in cluster state. types” it’s important to understand common problems related to Elasticsearch concepts: cluster, mapping, metadata. See detailed explanations below complete with common problems, examples and useful tips.

Mapping in Elasticsearch


Mapping is similar to database schemas that define the properties of each field in the index. These properties may contain the data type of each field and how fields are going to be tokenized and indexed. In addition, the mapping may also contain various advanced level properties for each field to define the options exposed by Lucene and Elasticsearch. You can create a mapping of an index using _mappings REST endpoint. The very first time Elasticsearch finds a new field, whose mapping is not pre-defined inside the index, it automatically tries to guess the data type and analyzer of that field and set its default value. For example, if you index an integer field without pre-defining the mapping, Elasticsearch sets the mapping of that field as long.

Examples

Create an index with predefined mapping:

PUT /my_index?pretty
{
  "settings": {
    "number_of_shards": 1
  },
  "mappings": {
    "properties": {
      "name": {
        "type": "text"
      },
      "age": {
        "type": "integer"
      }
    }
  }
}

Create mapping in an existing index:

PUT /my_index/_mapping?pretty
{
  "properties": {
    "email": {
      "type": "keyword"
    }
  }
}

View the mapping of an existing index:

GET my_index/_mapping?pretty

View the mapping of an existing field:

GET /my_index/_mapping/field/name?pretty

Notes
  • It is not possible to update the mapping of an existing field. If the mapping is set to the wrong type, re-creating the index with updated mapping and re-indexing is the only option available.
  • In version 7.0, Elasticsearch has deprecated the document type and the default document type is set to _doc. In future versions of Elasticsearch, the document type will be removed completely.

Common Problems
  • The most common problem in Elasticsearch is incorrectly defined mapping which limits the use functionality of the field. For example, if the data type of string field is set as text, you cannot use that field for aggregations, sorting or exact match filters. Similarly, if a string field is dynamically indexed without predefined mapping, Elasticsearch automatically creates two fields internally. One as a text type for full-text search and another as keyword type, which in most cases is a waste of space. 
  • Elasticsearch automatically creates an _all field inside the mapping and copies values of each field of a document inside the _all field. This field is used to search text without specifying a field name. Make sure to disable the _all field in production environments to avoid wasting space. Please note that support for _all field has been removed in version 7.0
  • In versions lower than 5.0, it was possible to create multiple document types inside an index, similar to creating multiple tables inside a database. In those versions, there were higher chances of getting data types conflicts across different document types if they contained the same field name with different data types. 
  • The mapping of each index is part of the cluster state and is managed by master nodes. If the mapping is too big, meaning there are thousands of fields in the index, the cluster state grows too large to be handled and creates the issue of mapping explosion, resulting in the slowness of the cluster.

Metadata in Elasticsearch

What it is

Metadata in Elasticsearch refers to storing some additional information for each document. This is achieved using the specific metadata fields available in Elasticsearch. The default behavior of some of these metadata fields can be customized during mapping creation.

Examples

Using _meta meta-field for storing application-specific information with the mapping:

PUT /my_index?pretty
{
  "mappings": {
    "_meta": { 
      "domain": "security",
      "release_information": {
        "date": "18-01-2020",
        "version": "7.5"
      }
    }
  }
}

Notes
  • In version 2.x, Elasticsearch had a total 13 meta fields available, which are: _index, _uid, _type, _id, _source, _size, _all, _field_names, _timestamp, _ttl, _parent, _routing, _meta
  • In version 5.x, _timestamp and _ttl meta fields were removed.
  • In version 6.x, the _parent meta field was removed.
  • In version 7.x, _uid and _all meta fields were removed.

To help troubleshoot related issues we have gathered selected Q&A from the community and issues from Github , please review the following for further information :

1 Process Cluster Event Timeout Excep  

2Github Issue Number 14905  


Log Context

Log ”[{}] failed to refresh-mapping in cluster state; types [{}]” classname is MetaDataMappingService.java
We have extracted the following from Elasticsearch source code to get an in-depth context :

                     }

                    logger.warn("[{}] re-syncing mappings with cluster state for types [{}]"; index; updatedTypes);
                    dirty = true;
                } catch (Throwable t) {
                    logger.warn("[{}] failed to refresh-mapping in cluster state; types [{}]"; index; refreshTask.types);
                }
            } else if (task instanceof UpdateTask) {
                UpdateTask updateTask = (UpdateTask) task;
                try {
                    String type = updateTask.type;






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