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


Failed to execute progress listener on list shards
Failed to execute progress listener on partial reduce
Failed to execute progress listener on reduce
Reloading search analyzers
Error occurred while reindexing bulk failures search failures
Realm is in user-search mode - base dn= search filter=
Clear SC failed on node
Giving up on search because it failed with a non-retryable exception
Ldap search timeout is less than the minimum supported search
Rollup index not found during rollup search
Failed to execute progress listener on query result
Failed to execute progress listener on query failure

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