Use Tablestore SDK for .NET to perform a match all query - Tablestore

You can use the match all query feature to match all rows in a table to query the total number of rows in the table or return multiple random rows.

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

Parameter	Description
Query	The type of the query. Set this parameter to MatchAllQuery.
TableName	The name of the data table.
IndexName	The name of the search index.
Limit	The maximum number of rows that you want the current query to return. To query only the number of rows that meet the query conditions without specific data, set this parameter to 0.
GetTotalCount	Specifies whether to return the total number of rows that meet the query conditions. Default value: false, which indicates that the total number of rows that meet the query conditions is not returned. If you set this parameter to true, the query performance is compromised.
ColumnsToGet	Specifies whether to return all columns in the rows that meet the query conditions. You can specify the ReturnAll, Columns, and ReturnAllFromIndex parameters. The default value of ReturnAll is false, which indicates that not all columns are returned. You can use one of the following methods to specify the columns that you want to return. If you do not use the following methods to specify the columns that you want to return, only the primary key columns are returned. Configure Columns to specify the columns that you want to return. Set ReturnAllFromIndex to true to return all columns from the search index. If you set ReturnAll to true, all columns are returned.

Example

The following sample code shows how to query the total number of rows in a table.

/// <summary>
/// Perform a match all query to query the total number of rows in a table. 
/// </summary>
/// <param name="otsClient"></param>
public static void MatchAllQuery(OTSClient otsClient)
{
    var searchQuery = new SearchQuery();
    searchQuery.Query = new MatchAllQuery();
    searchQuery.GetTotalCount = true; // Set the GetTotalCount parameter to true to return the total number of rows that meet the query conditions. 
    /*
    * In the result of a match all query, the value of the TotalCount parameter indicates the total number of rows in the table. 
    * To query only the number of rows that meet the query conditions without specific data, set the Limit parameter to 0. 
    */
    searchQuery.Limit = 0;
    var request = new SearchRequest(TableName, IndexName, searchQuery);

    var response = otsClient.Search(request);
    // Check whether all rows that meet the query conditions are returned. If the value of the isAllSuccess parameter is false, Tablestore may fail to query data on some servers, and not all rows that meet the query conditions are returned. 
    Console.WriteLine("IsAllSuccess:" + response.IsAllSuccess);
    Console.WriteLine("Total Count:" + response.TotalCount);
}

FAQ

How do I query the total number of rows in a table?

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.