Briefly, this error occurs when Elasticsearch is unable to retrieve the completion statistics for an operation. This could be due to a variety of reasons such as insufficient permissions, network issues, or a problem with the Elasticsearch cluster itself. To resolve this issue, you can check the user permissions, ensure the network connectivity is stable, and verify the health of the Elasticsearch cluster. If the problem persists, consider checking the Elasticsearch logs for more detailed error information.
This log is related to search problems, in addition to reading the guide below you can use the free Search Log Analyzer. With Opster’s Analyzer, you can easily locate slow searches and understand what led to them adding additional load to your system. The tool is free and takes just 2 minutes to run.
Overview
Search refers to the searching of documents in an index or multiple indices. The simple search is just a GET API request to the _search endpoint. The search query can either be provided in query string or through a request body.
Examples
When looking for any documents in this index, if search parameters are not provided, every document is a hit and by default 10 hits will be returned.
GET my_documents/_search
A JSON object is returned in response to a search query. A 200 response code means the request was completed successfully.
{
"took" : 1,
"timed_out" : false,
"_shards" : {
"total" : 2,
"successful" : 2,
"failed" : 0
},
"hits" : {
"total" : 2,
"max_score" : 1.0,
"hits" : [
...
]
}
}Notes and good things to know
- Distributed search is challenging and every shard of the index needs to be searched for hits, and then those hits are combined into a single sorted list as a final result.
- There are two phases of search: the query phase and the fetch phase.
- In the query phase, the query is executed on each shard locally and top hits are returned to the coordinating node. The coordinating node merges the results and creates a global sorted list.
- In the fetch phase, the coordinating node brings the actual documents for those hit IDs and returns them to the requesting client.
- A coordinating node needs enough memory and CPU in order to handle the fetch phase.
Log Context
Log “Could not get completion stats” classname is Completion090PostingsFormat.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :
CompletionTerms completionTerms = (CompletionTerms) terms;
completionStats.add(completionTerms.stats(fieldNamePatterns));
}
}
} catch (IOException ioe) {
logger.error("Could not get completion stats"; ioe);
}
}
return completionStats;
}
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