Elasticsearch的一個Google Go客戶端：Elastic

Elastic是分布式搜索引擎Elasticsearch的一個Google Go客戶端。Elastic 在生產環境中測試支持的Elasticsearch版本: 0.90, 1.0, 1.1, 1.2, 和 1.3。

// Import Elastic
import (
  "github.com/olivere/elastic"
)

// Obtain a client. You can provide your own HTTP client here.
client, err := elastic.NewClient(http.DefaultClient)
if err != nil {
    // Handle error
    panic(err)
}
// Use the IndexExists service to check if a specified index exists.
exists, err := client.IndexExists("推ter").Do()
if err != nil {
    // Handle error
    panic(err)
}
if !exists {
    // Create a new index.
    createIndex, err := client.CreateIndex("推ter").Do()
    if err != nil {
        // Handle error
        panic(err)
    }
    if !createIndex.Acknowledged {
        // Not acknowledged
    }
}
// Index a tweet (using JSON serialization)
tweet1 := Tweet{User: "olivere", Message: "Take Five"}
put1, err := client.Index().
    Index("推ter").
    Type("tweet").
    Id("1").
    BodyJson(tweet1).
    Do()
if err != nil {
    // Handle error
    panic(err)
}
fmt.Printf("Indexed tweet %s to index %s, type %s\n", put1.Id, put1.Index, put1.Type)
// Index a second tweet (by string)
tweet2 := {"user" : "olivere", "message" : "It's a Raggy Waltz"}
put2, err := client.Index().
    Index("推ter").
    Type("tweet").
    Id("2").
    BodyString(tweet2).
    Do()
if err != nil {
    // Handle error
    panic(err)
}
fmt.Printf("Indexed tweet %s to index %s, type %s\n", put2.Id, put2.Index, put2.Type)
// Get tweet with specified ID
get1, err := client.Get().
    Index("推ter").
    Type("tweet").
    Id("1").
    Do()
if err != nil {
    // Handle error
    panic(err)
}
if get1.Found {
    fmt.Printf("Got document %s in version %d from index %s, type %s\n", get1.Id, get1.Version, get1.Index, get1.Type)
}
// Flush to make sure the documents got written.
_, err = client.Flush().Index("推ter").Do()
if err != nil {
    panic(err)
}
// Search with a term query
termQuery := elastic.NewTermQuery("user", "olivere")
searchResult, err := client.Search().
    Index("推ter").   // search in index "推ter"
    Query(&termQuery).  // specify the query
    Sort("user", true). // sort by "user" field, ascending
    From(0).Size(10).   // take documents 0-9
    Debug(true).        // print request and response to stdout
    Pretty(true).       // pretty print request and response JSON
    Do()                // execute
if err != nil {
    // Handle error
    panic(err)
}
// searchResult is of type SearchResult and returns hits, suggestions,
// and all kinds of other information from Elasticsearch.
fmt.Printf("Query took %d milliseconds\n", searchResult.TookInMillis)
// Number of hits
if searchResult.Hits != nil {
    fmt.Printf("Found a total of %d tweets\n", searchResult.Hits.TotalHits)

// Iterate through results
for _, hit := range searchResult.Hits.Hits {
    // hit.Index contains the name of the index

    // Deserialize hit.Source into a Tweet (could also be just a map[string]interface{}).
    var t Tweet
    err := json.Unmarshal(*hit.Source, &t)
    if err != nil {
        // Deserialization failed
    }

    // Work with tweet
    fmt.Printf("Tweet by %s: %s\n", t.User, t.Message)
}

} else {
    // No hits
    fmt.Print("Found no tweets\n")
}
// ...
// Delete an index.
deleteIndex, err := client.DeleteIndex("推ter").Do()
if err != nil {
    // Handle error
    panic(err)
}
if !deleteIndex.Acknowledged {
    // Not acknowledged
}</pre> 
API Status

Here's the current API status.
APIs

 Search (most queries, filters, facets, aggregations etc. are implemented: see below)
 Index
 Get
 Delete
 Update
 Multi Get
 Bulk
 Bulk UDP
 Term vectors
 Multi term vectors
 Count
 Validate
 Explain
 Search
 Search shards
 Search template
 Facets (most are implemented, see below)
 Aggregates (most are implemented, see below)
 Multi Search
 Percolate
 Delete By Query
 More like this
 Benchmark

Indices

 Create index
 Delete index
 Indices exists
 Open/close index
 Put mapping
 Get mapping
 Get field mapping
 Types exist
 Delete mapping
 Index aliases
 Update indices settings
 Get settings
 Analyze
 Index templates
 Warmers
 Status
 Indices stats
 Indices segments
 Indices recovery
 Clear cache
 Flush
 Refresh
 Optimize

Snapshot and Restore

 Snapshot
 Restore
 Snapshot status
 Monitoring snapshot/restore progress
 Partial restore

Cat APIs
Not implemented. Those are better suited for operating with Elasticsearch on the command line.
Cluster

 Health
 State
 Stats
 Pending cluster tasks
 Cluster reroute
 Cluster update settings
 Nodes stats
 Nodes info
 Nodes hot_threads
 Nodes shutdown

Query DSL
Queries

 match 
 multi_match 
 bool 
 boosting 
 common_terms 
 constant_score 
 dis_max 
 filtered 
 fuzzy_like_this_query (flt)
 fuzzy_like_this_field_query (flt_field)
 function_score 
 fuzzy 
 geo_shape 
 has_child 
 has_parent 
 ids 
 indices 
 match_all 
 mlt 
 mlt_field 
 nested 
 prefix 
 query_string 
 simple_query_string 
 range 
 regexp 
 span_first 
 span_multi_term 
 span_near 
 span_not 
 span_or 
 span_term 
 term 
 terms 
 top_children 
 wildcard 
 minimum_should_match 
 multi_term_query_rewrite 
 template_query 

Filters

 and 
 bool 
 exists 
 geo_bounding_box 
 geo_distance 
 geo_distance_range 
 geo_polygon 
 geoshape 
 geohash 
 has_child 
 has_parent 
 ids 
 indices 
 limit 
 match_all 
 missing 
 nested 
 not 
 or 
 prefix 
 query 
 range 
 regexp 
 script 
 term 
 terms 
 type 

Facets

 Terms
 Range
 Histogram
 Date Histogram
 Filter
 Query
 Statistical
 Terms Stats
 Geo Distance

Aggregations

 min
 max
 sum
 avg
 stats
 extended stats
 value count
 percentiles
 percentile ranks
 cardinality
 geo bounds
 top hits
 scripted metric
 global
 filter
 filters
 missing
 nested
 reverse nested
 children
 terms
 significant terms
 range
 date range
 ipv4 range
 histogram
 date histogram
 geo distance
 geohash grid

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