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
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 a data table and Write data.
A search index is created for the data table. For more information, see Create a search index.
Parameters
Parameter | Description |
query | The type of the query. Set the query 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. 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 specific data, set the limit parameter to 0. |
columnsToGet | Specifies whether to return all columns of each row that meets the query conditions. You can specify the returnAll and columns fields for the columnsToGet 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. |
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. |
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
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.