Tablestore:Prefix 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

Sample code

The following sample code provides an example on how to query the rows whose value of Col_Keyword is prefixed with 'hangzhou':

/**
 * Query the rows in which the value of the Col_Keyword column contains the "hangzhou" prefix in a table. 
 */
func PrefixQuery(client *tablestore.TableStoreClient, tableName string, indexName string) {
    searchRequest := &tablestore.SearchRequest{}
    searchRequest.SetTableName(tableName)
    searchRequest.SetIndexName(indexName)
    query := &search.PrefixQuery{} // Set the query type to PrefixQuery. 
    query.FieldName = "Col_Keyword" // Specify the name of the field that you want to match. 
    query.Prefix = "hangzhou" // Specify the prefix that is used to match the value of the column. 
    searchQuery := search.NewSearchQuery()
    searchQuery.SetQuery(query)
    searchQuery.SetGetTotalCount(true)
    searchRequest.SetSearchQuery(searchQuery)
    // Return all columns in the rows that meet the query conditions. 
    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("TotalCount: ", searchResponse.TotalCount) // Display the total number of rows that meet the query conditions instead of the number of returned rows. 
    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))
    }
}

FAQ

• What do I do if no data can be found by calling the Search operation?

• How do I increase the value of the limit parameter to 1000 when I call the Search operation of the search index feature to query data?

• 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 Parallel scan.