Tablestore:Perform a Boolean 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 data tables and Write data.

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

Parameters

Example

The following sample code shows how to perform a Boolean query that consists of Boolean subqueries. In this example, the rows in which the value of the Keyword_type_col column is "SearchIndex" or "TableStore" are queried. All columns in the search index are returned.

/// <summary>
/// A Boolean query contains one or more subqueries. Each subquery has its own type. 
/// MustQueries: The rows must meet all subquery conditions. 
/// ShouldQueries: More than one condition is specified by the ShouldQueries parameter. If a row meets at least one condition, the row meets the query conditions. 
/// MustNotQueries: The rows must not meet the conditions. 
/// MinimumShouldMatch: The rows must meet the minimum number of conditions. 
/// </summary>
/// <param name="otsClient"></param>
public static void BoolQuery(OTSClient otsClient)
{
    Console.WriteLine("\n Start bool query...");

    var searchQuery = new SearchQuery();
    // Return the total number of rows that meet the query conditions. 
    searchQuery.GetTotalCount = true;
    var boolQuery = new BoolQuery();
    var shouldQuerys = new List<IQuery>();
    shouldQuerys.Add(new TermQuery(Keyword_type_col, new ColumnValue("SearchIndex")));
    shouldQuerys.Add(new TermQuery(Keyword_type_col, new ColumnValue("TableStore")));
    boolQuery.ShouldQueries = shouldQuerys;
    boolQuery.MinimumShouldMatch = 1;

    searchQuery.Query = boolQuery;

    var request = new SearchRequest(TableName, IndexName, searchQuery);
    // You can specify the ColumnsToGet parameter to return the columns that you specify, all columns in the rows that meet the query conditions, or all columns in the search index. If you do not specify this parameter, only the primary key columns are returned. 
    request.ColumnsToGet = new ColumnsToGet()
    {
        // Return all columns in the search index. 
        ReturnAllFromIndex = true
        // Return the columns that you specify. 
        //Columns = new List<string>() { Long_type_col, Text_type_col, Keyword_type_col }
        // Return all columns in the rows that meet the query conditions. 
        //ReturnAll = true
    };

    var response = otsClient.Search(request);

    Console.WriteLine("Total Count:" + response.TotalCount); // Display the total number of rows that meet the query conditions instead of the number of returned rows. 
    foreach (var row in response.Rows)
    {
        PrintRow(row);
    }
}

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, Boolean query, geo query, nested query, and exists query. You can use different query methods 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.