Elasticsearch Search



Elasticsearch Search

Opster Team

July 2020, Version: 1.7-8.0


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Search in Elasticsearch

What it is

Search refers to the searching of documents in an index or multiple indices. The simple search is just a GET request to _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 will mean the request completed successfully.

{
"took" : 1,
"timed_out" : false,
"_shards" : {
"total" : 2,
"successful" : 2,
"failed" : 0
},
"hits" : {
"total" : 2,
"max_score" : 1.0,
"hits" : [
...
]
}
}
Notes
  • 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.

Related log errors to this ES concept


Failed to execute input for watch ; reason
Realm is in user-search mode basedn=; search filter=
Giving up on search because it failed with a non-retryable exception
Rollup index not found during rollup search.
OnFreeContext listener failed
OnNewContext listener failed
Clear SC failed on node
Ldapsearch timeout is less than the minimum supported search
Failed to process shard failure to potentially send back shard failure on corruption
Error occurred while reindexing; bulk failures ; search failures
OnQueryPhase listener failed
OnNewScrollContext listener failed

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