Summaries and highlighting

Prerequisites

• An OTSClient instance is initialized. For more information, see Initialize an OTSClient instance.

• A data table is created and data is written to the data table. For more information, see Create a data table and Write data.

• A search index is created for the data table. For more information, see Create search indexes.

Notes

• When you use the summary and highlighting feature with a MatchQuery or MatchPhraseQuery, the matched terms may be highlighted by multiple pre-tags and post-tags.

• If the tokenizer type for the Text field is maximum semantic tokenization, the summary and highlighting feature is not supported when you use a MatchPhraseQuery to query data.

• Fragment splitting may divide a matched term in the text. In this case, the term may not be highlighted.

Parameters

Example

The following example shows how to use MatchQuery to find data where the Col_Text column matches hangzhou shanghai and how to highlight the search query in the results. The Col_Text column is a Text type.

func MatchQuerywithHighlight(client *tablestore.TableStoreClient, tableName string, indexName string) {
    searchRequest := &tablestore.SearchRequest{}
    searchRequest.SetTableName(tableName)
    searchRequest.SetIndexName(indexName)
    query := &search.MatchQuery{} // Set the query type to MatchQuery.
    query.FieldName = "Col_Text"   // Set the column to match.
    query.Text = "hangzhou shanghai"     // Set the value to match.
    searchQuery := search.NewSearchQuery()
    searchQuery.SetQuery(query)
    highlight := &search.Highlight{
        FieldHighlightParameters: map[string]*search.HighlightParameter{
            "Col_Text": {
                NumberOfFragments: proto.Int32(5),
                PreTag:            proto.String(""),
                PostTag:           proto.String(""),
            },
        },
    }
    searchQuery.SetHighlight(highlight)
    searchQuery.SetGetTotalCount(true)
    searchQuery.SetOffset(0) // Set offset to 0.
    searchQuery.SetLimit(20) // Set limit to 20 to return a maximum of 20 rows.
    searchRequest.SetSearchQuery(searchQuery)
    // Set to return all columns from the search index.
    searchRequest.SetColumnsToGet(&tablestore.ColumnsToGet{
        ReturnAllFromIndex: true,
    })

    if resp, err := client.Search(searchRequest); err != nil {
        fmt.Println("Highlighting query failed with err: ", err)
    } else {
        fmt.Println("RequestId: " + resp.RequestId)
        // Print the query and highlight results. Set padding to empty when you query non-nested fields.
        printSearchHit(resp.SearchHits, " ")
    }
    fmt.Println("highlight query finished")
}

/**
 * Prints the content of searchHit.
 * @param searchHits The search hits.
 * @param padding When printing a nested structure, add a prefix to show the hierarchy.
 */
func printSearchHit(searchHits []*tablestore.SearchHit, padding string) {
    for _, searchHit := range searchHits {
        if searchHit.Score != nil {
            fmt.Printf("%sScore: %f\n", padding, *searchHit.Score)
        }

        if searchHit.Row != nil {
            jsonBody, err := json.Marshal(*searchHit.Row)
            if err != nil {
                panic(err)
            }
            fmt.Println("Row: ", string(jsonBody))
        }

        if searchHit.HighlightResultItem != nil && len(searchHit.HighlightResultItem.HighlightFields) != 0 {
            fmt.Printf("%sHighlight: \n", padding)
            for colName, highlightResult := range searchHit.HighlightResultItem.HighlightFields {
                fmt.Printf("%sColumnName: %s, Highlight_Fragments: %v\n", padding+padding, colName, highlightResult.Fragments)
            }
        }

        fmt.Println("")
    }
}

References

• For more information about the summary and highlighting feature, see Summaries and highlighting.

• To use the summary and highlighting feature when you query nested fields, see Nested query.