Tablestore:Nested query

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.

Parameters

Examples

func NestedQuery(client *tablestore.TableStoreClient, tableName string, indexName string) {
    searchRequest := &tablestore.SearchRequest{}
    searchRequest.SetTableName(tableName)
    searchRequest.SetIndexName(indexName)
    query := &search.NestedQuery{ // Set the query type to NestedQuery. 
        Path: "col_nested", // Specify the path of the Nested field. 
        Query: &search.TermQuery{ // Construct a subquery for the nested query. 
            FieldName: "col_nested.nested_1", // Specify the name of the field that you want to query. The field name must contain the col_nested prefix. 
            Term:      "tablestore",          // Specify the keyword that is used to match the value of the field. 
        },
        ScoreMode: search.ScoreMode_Avg,
    }
    searchQuery := search.NewSearchQuery()
    searchQuery.SetQuery(query)
    searchRequest.SetSearchQuery(searchQuery)
    // Specify that all fields are returned. 
    searchRequest.SetColumnsToGet(&tablestore.ColumnsToGet{
        ReturnAll: true,
    })
    searchResponse, err := client.Search(searchRequest)
    if err != nil {
        fmt.Printf("%#v", err)
        return
    }
    fmt.Println("IsAllSuccess: ", searchResponse.IsAllSuccess) // Check whether all rows that meet the query conditions are returned. 
    fmt.Println("RowCount: ", len(searchResponse.Rows))
    for _, row := range searchResponse.Rows {
        jsonBody, err := json.Marshal(row)
        if err != nil {
            panic(err)
        }
        fmt.Println("Row: ", string(jsonBody))
    }
}

func NestedQueryWithHighlight(client *tablestore.TableStoreClient, tableName string, indexName string) {
	searchRequest := &tablestore.SearchRequest{}
	searchRequest.SetTableName(tableName)
	searchRequest.SetIndexName(indexName)
	query := &search.NestedQuery{ // Set the query type to NestedQuery. 
		Path: "col_nested", // Specify the path of the Nested field. 
		Query: &search.TermQuery{ // Construct a subquery for the nested query. 
			FieldName: "col_nested.nested_1", // Specify the name of the field that you want to query. The field name must contain the col_nested prefix. 
			Term:      "tablestore",          // Specify the value that you want to match. 
		},
		ScoreMode: search.ScoreMode_Avg,
		InnerHits: &search.InnerHits{
			Offset: proto.Int32(0),
			Limit:  proto.Int32(3),
			Highlight: &search.Highlight{
				FieldHighlightParameters: map[string]*search.HighlightParameter{
					"col_nested.nested_1": {
						NumberOfFragments: proto.Int32(5),
						PreTag:            proto.String("<em>"),
						PostTag:           proto.String("</em>"),
					},
				},
			},
		},
	}
	searchQuery := search.NewSearchQuery()
	searchQuery.SetQuery(query)
	searchRequest.SetSearchQuery(searchQuery)
	// Specify that all fields are returned. 
	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)
                // Display the highlighted results. 
		printSearchHit(resp.SearchHits, " ")
	}
	fmt.Println("highlight query finished")
}


/**
 * Display the content that meets the query conditions. 
 * @param searchHits searchHits
 * If the output uses the @param prefix Nested structure, add the prefix to display the hierarchy information. 
 */
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.NestedDocOffset != nil {
			fmt.Printf("%sOffset: %d\n", padding, *searchHit.NestedDocOffset)
		}

		if searchHit.Row != nil {
			fmt.Printf("%sRow: %v\n", padding, *searchHit.Row)
		}

		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)
			}
		}

		if searchHit.SearchInnerHits != nil && len(searchHit.SearchInnerHits) != 0 {
			fmt.Printf("%sInnerHits: \n", padding)
			for path, innerSearchHit := range searchHit.SearchInnerHits {
				fmt.Printf("%sPath: %s\n", padding+padding, path)
				fmt.Printf("%sSearchHit: \n", padding+padding)
				printSearchHit(innerSearchHit.SearchHits, padding+padding)
			}
		}

		fmt.Println("")
	}
}

FAQ

• What do I do if no data is found when I call the Search operation?

• Why does a token become invalid when pagination is used in a search index-based query?

References

• When you use a search index to query data, you can use the following query methods: term query, terms query, match all query, match query, match phrase query, prefix query, range query, wildcard query, geo query, Boolean query, KNN vector query, nested query, and exists query. You can use the query methods provided by the search index to query data from multiple dimensions based on your business requirements.

  You can sort or paginate rows that meet the query conditions by using the sorting and paging features. For more information, see Sorting and paging.

  You can use the collapse (distinct) feature to collapse the result set based on a specific column. This way, data of the specified type appears only once in the query results. For more information, see Collapse (distinct).

• If you want to analyze data in a data table, you can use the aggregation feature of the Search operation or execute SQL statements. For example, you can obtain the minimum and maximum values, sum, and total number of rows. For more information, see Aggregation and SQL query.

• If you want to obtain all rows that meet the query conditions without the need to sort the rows, you can call the ParallelScan and ComputeSplits operations to use the parallel scan feature. For more information, see Perform a parallel scan.