Elasticsearch Search

By Opster Team

Updated: Jan 28, 2024

| 1 min read

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.

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Related log errors to this ES concept


No mapping found for fieldName in order to sort on
Invalid alias filter
Unknown alias name was passed to alias Filter
Failed to parse load source
Failed to load field
Invalid token in inner hits array
Could not parse inner query
Rescore doesn t support fieldName
Missing rescore type
Rescore Phase Failed
Failed to fetch doc id docId
Error filtering source

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