All Products
Search
Document Center

Tablestore:Exists query

Last Updated:Feb 13, 2025

An exists query is also called a NULL query or NULL-value query. This query is used in sparse data to determine whether a column of a row exists. For example, you can query the rows in which the value of the address column is not empty.

Note
  • If you want to perform an exists query on a Nested column, you can use nested query.

  • If you want to check whether a column contains empty values, you must use ExistsQuery together with mustNotQueries of BoolQuery.

  • If one of the following conditions is met, the system considers that a column does not to exist. In this example, the city column is used.

    • The type of the city column in the search index is a basic type such as keyword. If a row in which the city column does not exist in the data table, the search index considers that the city column does not exist.

    • The type of the city column in the search index is a basic type such as keyword. If a row in which the value of the city column is an empty array in the data table ("city" = "[]"), the search index considers that the city column does not exist.

Prerequisites

Parameters

Parameter

Description

fieldName

The name of the column that you want to query.

query

The query type. Set this parameter to ExistsQuery.

getTotalCount

Specifies whether to return the total number of rows that meet the query conditions. The default value of this parameter is false, which specifies 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.

tableName

The name of the data table.

indexName

The name of the search index.

columnsToGet

Specifies whether to return all columns of each row that meets the query conditions. You can configure the returnAll and columns fields for this parameter.

The default value of the returnAll field is false, which specifies that not all columns are returned. In this case, you can use the columns field 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 you set the returnAll field to true, all columns are returned.

Examples

The following sample code provides an example on how to query all rows in which the specified column is not empty.

public static void existQuery(SyncClient syncClient) {
    // Query whether the col_keyword field exists. The col_keyword field is not a Nested field. 
    {
        {
            // The following sample code provides an example on how to query whether a field of a non-Nested type exists. 
            SearchQuery searchQuery = new SearchQuery();
            ExistsQuery existQuery = new ExistsQuery(); // Set the query type to ExistsQuery. 
            existQuery.setFieldName("col_keyword");
            searchQuery.setQuery(existQuery);
            SearchRequest searchRequest = new SearchRequest("<TABLE_NAME>", "<SEARCH_INDEX_NAME>", searchQuery);
            SearchResponse resp = syncClient.search(searchRequest);
        }
        {
            // Construct a builder. 
            SearchResponse resp = syncClient.search(SearchRequest.newBuilder()
                    .indexName("<SEARCH_INDEX_NAME>")
                    .tableName("<TABLE_NAME>")
                    .searchQuery(
                            SearchQuery.newBuilder()
                                    .query(QueryBuilders.exists("col_keyword"))
                                    .limit(10)
                                    .build())
                    .build());
        }
    }
    // The Nested structure is [{"keyword":"a","long":123}]. 
    {
        // Query whether the col_nested parent field exists. The col_nested field is of the Nested type. 
        {
            SearchResponse resp = syncClient.search(SearchRequest.newBuilder()
                    .indexName("<SEARCH_INDEX_NAME>")
                    .tableName("<TABLE_NAME>")
                    .searchQuery(
                            SearchQuery.newBuilder()
                                    .query(QueryBuilders.nested()
                                            .scoreMode(ScoreMode.None)
                                            .path("col_nested")
                                            .query(QueryBuilders.exists("col_nested")))
                                    .limit(10)
                                    .getTotalCount(false)
                                    .build())
                    .build());
        }
        // Query whether the col_nested.keyword field exists. The col_nested.keyword field is of the Nested type. 
        {
            SearchResponse resp = syncClient.search(SearchRequest.newBuilder()
                    .indexName("<SEARCH_INDEX_NAME>")
                    .tableName("<TABLE_NAME>")
                    .searchQuery(
                            SearchQuery.newBuilder()
                                    .query(QueryBuilders.nested()
                                            .scoreMode(ScoreMode.None)
                                            .path("col_nested")
                                            .query(QueryBuilders.exists("col_nested.keyword")))
                                    .limit(10)
                                    .getTotalCount(false)
                                    .build())
                    .build());
        }
    }
}

FAQ

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, KNN vector query, Boolean query, nested query, and exists query. After you create a search index, 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 table, you can call the Search operation to use the aggregation feature or use the SQL query feature. For example, you can query the maximum and minimum values, the sum of the values, and the 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.