Match all query by using Tablestore SDK for Java - Tablestore

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

Prerequisites

The OTSClient is initialized. For more information, see Initialize an OTSClient instance.
A data table is created. Data is written to the table.
A search index is created for the data table. For more information, see Create a search index.

Parameters

Parameter	Description
query	The query type. Set the query type 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. If you want the current query to return multiple random rows of data, set limit to a positive integer. To query only the number of matched rows without returning specific data, you can set limit to 0. This way, Tablestore returns the number of matched rows without data from the table.
columnsToGet	Specifies whether to return all columns. By default, returnAll is false, which specifies that not all columns are returned. In this case, you can use columns to specify the columns that you want to return. If you do not specify the columns that you want to return, only the primary key columns are returned. If returnAll is set to true, all columns are returned.
getTotalCount	Specifies whether to return the total number of rows that match the query conditions. By default, getTotalCount is false, which specifies that the total number of rows that match the query conditions is not returned. If this parameter is set to true, the query performance is compromised.

Sample code

The following sample code provides an example on how to query the total number of rows in a table:

/**
 * Use the match all query feature to query the total number of rows in a table. 
 * @param client
 */
private static void matchAllQuery(SyncClient client) {
    SearchQuery searchQuery = new SearchQuery();

    /**
    * Set the query type to MatchAllQuery. 
    */
    searchQuery.setQuery(new MatchAllQuery()); 

    /**
     * In the MatchAllQuery-based query result, the value of TotalCount is the total number of rows in the table. 
     * If you want the current query to return multiple random rows of data, set the limit parameter to a positive integer. 
     * To query only the number of rows that meet the query conditions without querying specific data of the rows, set the limit parameter to 0. 
     */
    searchQuery.setLimit(0);
    SearchRequest searchRequest = new SearchRequest("<TABLE_NAME>", "<SEARCH_INDEX_NAME>", searchQuery);

    /**
    * Specify that the total number of rows that meet the query conditions is returned. 
    */ 
    searchQuery.setGetTotalCount(true);
    SearchResponse resp = client.search(searchRequest);
    /**
     * Check whether the returned total number of rows that meet the query conditions is correct. If isAllSuccess is false, Tablestore may fail to query data on all servers and return a value that is smaller than the total number of rows that meet the query conditions. 
     */
    if (!resp.isAllSuccess()) {
        System.out.println("NotAllSuccess!");
    }
    System.out.println("IsAllSuccess: " + resp.isAllSuccess());
    System.out.println("TotalCount: " + resp.getTotalCount()); // Display the total number of rows that meet the query conditions. 
    System.out.println(resp.getRequestId());
}

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, 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 Perform 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.