Before you begin reading this guide, we recommend you try running the Elasticsearch Error Check-Up which can resolve issues causing many log errors (free and no installation required)
This guide will help you check for common problems that cause the log “Adding template for index patterns” 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, index, metadata, template.
Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up which analyses ES to discover the cause of many errors and provides suitable actionable recommendations.
Index in Elasticsearch
What it is
In Elasticsearch, an index (indices in plural) can be thought of as a table inside a database that has 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 below command:
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 </div> </div>
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.
Log Context
Log”Adding template [{}] for index patterns {}” classname is MetaDataIndexTemplateService.java
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
}
IndexTemplateMetaData template = templateBuilder.build();
MetaData.Builder builder = MetaData.builder(currentState.metaData()).put(template);
logger.info("adding template [{}] for index patterns {}"; request.name; request.indexPatterns);
return ClusterState.builder(currentState).metaData(builder).build();
}
Override
public void clusterStateProcessed(String source; ClusterState oldState; ClusterState newState) {
Related issues to this log
We have gathered selected Q&A from the community and issues from Github, that can help fix related issues please review the following for further information :
1 Elasticsearch index-patterns on template without wildcards -views 0.05 K ,score –
2 ElasticSearch – what is the difference between an index template and an index pattern -views 2.10 K,score 1
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