You can use the collapse (distinct) feature to collapse the result set based on a specified column when the results of a query contain large amounts of data of a specific type. Data of the specific type is displayed only once in the query results to ensure diversity of the result types.

Prerequisites

  • An OTSClient instance is initialized. For more information, see Initialization.
  • 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 search indexes.

Usage notes

  • If you use the collapse (distinct) feature, you can perform pagination only by specifying offset and limit instead of token.
  • If you aggregate and collapse a result set at the same time, the result set is aggregated before it is collapsed.
  • If you collapse the query results, the total number of results that are returned is determined by the sum of the offset and limit values. A maximum of 50,000 results can be returned.
  • The total number of rows in the response indicates the number of rows that meet the query conditions before you use the collapse (distinct) feature. After the result set is collapsed, the total number of distinct values cannot be queried.

Parameters

ParameterDescription
table_nameThe name of the table.
index_nameThe name of the search index.
queryThe query type. You can set this parameter to any query type.
collapseThe configuration of the collapse parameters, including field_name.

field_name: the name of the column based on which the result set is collapsed. Only columns whose values are of the INTEGER, FLOATING-POINT and KEYWORD data types are supported.

offsetThe position from which the current query starts.
limitThe maximum number of rows that the current query returns.

To query only the number of matched rows without returning specific data, you can set limit to 0. Then, Tablestore returns the number of matched rows without data from the table.

Examples

$request = array(
    'table_name' => 'php_sdk_test',
    'index_name' => 'php_sdk_test_search_index',
    'search_query' => array(
        'offset' => 0,
        'limit' => 10,
        'get_total_count' => true,
        'collapse' => array(
            'field_name' => 'keyword'
        ),
        'query' => array(
            'query_type' => QueryTypeConst::MATCH_ALL_QUERY
        ),
//        'sort' => array(// Specify a specific sorting method if required. 
//            array(
//                'field_sort' => array(
//                    'field_name' => 'keyword',
//                    'order' => SortOrderConst::SORT_ORDER_ASC
//                )
//            ),
//        ),
        'token' => null,
    ),
    'columns_to_get' => array(
        'return_type' => ColumnReturnTypeConst::RETURN_SPECIFIED,
        'return_names' => array('col1', 'col2')
    )
);
$response = $otsClient->search($request);