OpenSearch provides a powerful search API that allows you to search for documents in an index. The search API supports a number of parameters that allow you to customize the search operation. In this guide, we will explore the search API and its parameters.
Let's start by creating an index and adding some documents to it:
package main
import (
"context"
"fmt"
"os"
"strconv"
"strings"
"github.com/opensearch-project/opensearch-go/v3/opensearchapi"
)
func main() {
if err := example(); err != nil {
fmt.Println(fmt.Sprintf("Error: %s", err))
os.Exit(1)
}
}
func example() error {
client, err := opensearchapi.NewDefaultClient()
if err != nil {
return err
}
ctx := context.Background()
exampleIndex := "movies"
createResp, err := client.Indices.Create(ctx, opensearchapi.IndicesCreateReq{Index: exampleIndex})
if err != nil {
return err
}
fmt.Printf("Created: %t\n", createResp.Acknowledged)
for i := 1; i < 11; i++ {
_, err = client.Index(
ctx,
opensearchapi.IndexReq{
Index: exampleIndex,
DocumentID: strconv.Itoa(i),
Body: strings.NewReader(fmt.Sprintf(`{"title": "The Dark Knight %d", "director": "Christopher Nolan", "year": %d}`, i, 2008+i)),
},
)
if err != nil {
return err
}
}
_, err = client.Index(
ctx,
opensearchapi.IndexReq{
Index: exampleIndex,
Body: strings.NewReader(`{"title": "The Godfather", "director": "Francis Ford Coppola", "year": 1972}`),
},
)
if err != nil {
return err
}
_, err = client.Index(
ctx,
opensearchapi.IndexReq{
Index: exampleIndex,
Body: strings.NewReader(`{"title": "The Shawshank Redemption", "director": "Frank Darabont", "year": 1994}`),
},
)
if err != nil {
return err
}
_, err = client.Indices.Refresh(ctx, &opensearchapi.IndicesRefreshReq{Indices: []string{exampleIndex}})
if err != nil {
return err
}The search API allows you to search for documents in an index. The following example searches for ALL documents in the movies index:
searchResp, err := client.Search(ctx, &opensearchapi.SearchReq{Indices: []string{exampleIndex}})
if err != nil {
return err
}
respAsJson, err := json.MarshalIndent(searchResp, "", " ")
if err != nil {
return err
}
fmt.Printf("Search Response:\n%s\n", string(respAsJson))You can also search for documents that match a specific query. The following example searches for documents that match the query dark knight:
searchResp, err = client.Search(
ctx,
&opensearchapi.SearchReq{
Indices: []string{exampleIndex},
Params: opensearchapi.SearchParams{Query: `title: "dark knight"`},
},
)
if err != nil {
return err
}
respAsJson, err = json.MarshalIndent(searchResp, "", " ")
if err != nil {
return err
}
fmt.Printf("Search Response:\n%s\n", string(respAsJson))OpenSearch query DSL allows you to specify complex queries. Check out the OpenSearch query DSL documentation for more information.
The search API allows you to paginate through the search results. The following example searches for documents that match the query dark knight, sorted by year in ascending order, and returns the first 2 results after skipping the first 5 results:
searchResp, err = client.Search(
ctx,
&opensearchapi.SearchReq{
Indices: []string{exampleIndex},
Params: opensearchapi.SearchParams{
Query: `title: "dark knight"`,
Size: opensearchapi.ToPointer(2),
From: opensearchapi.ToPointer(5),
Sort: []string{"year:desc"},
},
},
)
if err != nil {
return err
}
respAsJson, err = json.MarshalIndent(searchResp, "", " ")
if err != nil {
return err
}
fmt.Printf("Search Response:\n%s\n", string(respAsJson))When retrieving large amounts of non-real-time data, you can use the scroll parameter to paginate through the search results.
searchResp, err = client.Search(
ctx,
&opensearchapi.SearchReq{
Indices: []string{exampleIndex},
Params: opensearchapi.SearchParams{
Query: `title: "dark knight"`,
Size: opensearchapi.ToPointer(2),
Sort: []string{"year:desc"},
Scroll: time.Minute,
},
},
)
if err != nil {
return err
}
respAsJson, err = json.MarshalIndent(searchResp, "", " ")
if err != nil {
return err
}
fmt.Printf("Search Response:\n%s\n", string(respAsJson))The scroll example above has one weakness: if the index is updated while you are scrolling through the results, they will be paginated inconsistently. To avoid this, you should use the "Point in Time" feature. The following example demonstrates how to use the point_in_time and pit_id parameters to paginate through the search results:
pitCreateResp, err := client.PointInTime.Create(
ctx,
opensearchapi.PointInTimeCreateReq{
Indices: []string{exampleIndex},
Params: opensearchapi.PointInTimeCreateParams{KeepAlive: time.Minute},
},
)
if err != nil {
return err
}
searchResp, err = client.Search(
ctx,
&opensearchapi.SearchReq{
Body: strings.NewReader(fmt.Sprintf(`{ "pit": { "id": "%s", "keep_alive": "1m" } }`, pitCreateResp.PitID)),
Params: opensearchapi.SearchParams{
Size: opensearchapi.ToPointer(5),
Sort: []string{"year:desc"},
},
},
)
if err != nil {
return err
}
respAsJson, err = json.MarshalIndent(searchResp, "", " ")
if err != nil {
return err
}
fmt.Printf("Search Response:\n%s\n", string(respAsJson))
searchResp, err = client.Search(
ctx,
&opensearchapi.SearchReq{
Body: strings.NewReader(fmt.Sprintf(`{ "pit": { "id": "%s", "keep_alive": "1m" }, "search_after": [ "1994" ] }`, pitCreateResp.PitID)),
Params: opensearchapi.SearchParams{
Size: opensearchapi.ToPointer(5),
Sort: []string{"year:desc"},
},
},
)
if err != nil {
return err
}
respAsJson, err = json.MarshalIndent(searchResp, "", " ")
if err != nil {
return err
}
fmt.Printf("Search Response:\n%s\n", string(respAsJson))
_, err = client.PointInTime.Delete(ctx, opensearchapi.PointInTimeDeleteReq{PitID: []string{pitCreateResp.PitID}})
if err != nil {
return err
}Note that a point-in-time is associated with an index or a set of index. So, when performing a search with a point-in-time, you DO NOT specify the index in the search.
The source API returns the source of the documents with included or excluded fields. The following example returns all fields from document source in the movies index:
sourceResp, err := client.Document.Source(
ctx,
opensearchapi.DocumentSourceReq{
Index: "movies",
DocumentID: "1",
},
)
if err != nil {
return err
}
respAsJson, err = json.MarshalIndent(sourceResp, "", " ")
if err != nil {
return err
}
fmt.Printf("Source Response:\n%s\n", string(respAsJson))To include certain fields in the source response, use SourceIncludes or Source(this field is deprecated and SourceIncludes is recommended to be used instead). To get only required fields:
sourceResp, err := client.Document.Source(
ctx,
opensearchapi.DocumentSourceReq{
Index: "movies",
DocumentID: "1",
Params: opensearchapi.DocumentSourceParams{
SourceIncludes: []string{"title"},
},
},
)
if err != nil {
return err
}
respAsJson, err = json.MarshalIndent(sourceResp, "", " ")
if err != nil {
return err
}
fmt.Printf("Source Response:\n%s\n", string(respAsJson))To exclude certain fields in the source response, use SourceExcludes as follows:
sourceResp, err = client.Document.Source(
ctx,
opensearchapi.DocumentSourceReq{
Index: "movies",
DocumentID: "1",
Params: opensearchapi.DocumentSourceParams{
SourceExcludes: []string{"title"},
},
},
)
if err != nil {
return err
}
respAsJson, err = json.MarshalIndent(sourceResp, "", " ")
if err != nil {
return err
}
fmt.Printf("Source Response:\n%s\n", string(respAsJson)) delResp, err := client.Indices.Delete(
ctx,
opensearchapi.IndicesDeleteReq{
Indices: []string{"movies"},
Params: opensearchapi.IndicesDeleteParams{IgnoreUnavailable: opensearchapi.ToPointer(true)},
},
)
if err != nil {
return err
}
fmt.Printf("Deleted: %t\n", delResp.Acknowledged)
return nil
}