How To Solve Issues Related to Log – No river _meta document found after attempts

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Updated: Feb-20

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Troubleshooting background

To troubleshoot Elasticsearch log “No river _meta document found after attempts” it’s important to understand common problems related to Elasticsearch concepts: document, routing. See detailed explanations below complete with common problems, examples and useful tips.

Document in Elasticsearch

Overview

A document is simply a json document that is stored in Elasticsearch index. It consists of one or more fields; where each field has its own data type. This field type defines the type of data that can be stored in the field such as integer, string, object. Document is schema-free, which means we do not require to specify schema before indexing document, when a field is indexed for the first time, its type is decided and set.

Examples:

Creating A document : to create a document in the users index.

POST  /users/_doc 
{
    "name" : "Petey",
    "lastname" : "Cruiser",
    "email" : "petey@gmail.com"
}

In the above request, we haven’t mentioned id for the document so index operation generates a unique ID for the document. Here _doc is the type of document. We can provide this type to user-defined type also where user index may store user type document.

POST  /users/_doc/1
{
    "name" : "Petey",
    "lastname" : "Cruiser",
    "email" : "petey@gmail.com"
}

In the above query, the document will be created with id 1.

You can use the below ‘GET’ query to get a document from the index using id

GET  /users/_doc/1

Bellow is the result containing the document (in _source field) with metadata:-

{
    "_index": "users",
    "_type": "_doc",
    "_id": "1",
    "_version": 1,    "_seq_no": 1,    "_primary_term": 1,
    "found": true,
    "_source": {
        "name": "Petey",
        "lastname": "Cruiser",
        "email": "petey@gmail.com"
    }
}
Notes

Starting version 7.0 types are deprecated, so for backward compatibility on version 7.x all docs are under type ‘_doc’, starting 8.x type will be completely removed from ES APIs

Routing in Elasticsearch

What it is

In Elasticsearch, routing refers to document routing. When you index a document, Elasticsearch will determine which shard will be used to index the document to. 

The shard is selected based on the following formula:

shard = hash(_routing) % number_of_primary_shards

Where the default value of _routing is _id.
It is important to know which shard the document is routed to, because Elasticsearch will need to determine where to find that document later on for document retrieval requests. 

Examples

In twitter index with 2 primary shards, the document with _id equal to “440” gets routed to the shard number:   

shard = hash( 440 ) % 2
PUT twitter/_doc/440
{
...
}

Notes
  • In order to improve search performance speed you can create custom routing. For example, you can enable custom routing that will ensure only a single shard is queried (the shard that contains your data).
  • To create custom routing in Elasticsearch, you will need to configure and define  that not all routing will be completed by default settings. ( v <= 5.0)
PUT my_index/customer/_mapping
{
   "order":{
      "_routing":{
         "required":true
      }
   }
}
  •  This will ensure that every document in the “customer” type must specify a custom routing.  For elasticsearch 6 or above you will need to update the same mapping as:
PUT my_index/_mapping
{
   "order":{
      "_routing":{
         "required":true
      }
   }
}


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 :

 

 


Log Context

Log ”no river _meta document found after {} attempts” classname is RiversRouter.java
We have extracted the following from Elasticsearch source code to get an in-depth context :

 

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