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


Cannot find an aggregation named aggName in
Encountered more than one weight for a
Aggregator name of type
Rescore TopHits Failed
Registry miss-match - expected MetricAggregatorSupplier found
Registry miss-match - expected MinMaxAggregatorSupplier found
Registry miss-match - expected CardinalityAggregatorSupplier found
Registry miss-match - expected PercentilesAggregatorSupplier found
Registry miss-match - expected
ValuesSource type valuesSource toString is not supported for aggregation
Registry miss-match - expected MedianAbsoluteDeviationAggregatorSupplier found
Registry miss-match - expected ValueCountAggregatorSupplier found

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