Delete Group Data in Cache with SQL
This feature is only available in NCache Enterprise.
Similar to searching with SQL, NCache provides object queries through which you use criteria given in a query to delete result sets. To delete the data in the cache according to your specified criteria, NCache provides you with an extension of SQL.
A special keyword
$Group$ is used to specify that the condition under consideration uses group. A query with the searching criteria is executed using
ExecuteNonQuery processes the query on the server side and then sends the result to the client in the tabular form to the
ICacheReader type of instance.
- To learn about the standard prerequisites required to work with all NCache client-side features please refer to the given page on Client Side API Prerequisites.
- Custom classes/searchable attributes must be indexed as explained in Configuring Query Indexes.
- For API details refer to: ICache, ICacheReader, QueryCommand, ExecuteNonQuery, SearchService.
Given certain criteria, you can remove groups present in the cache with SQL queries. The following example removes all the data against a certain group through the SQL delete query.
// Preconditions: Cache is already connected // A user wants to remove the West Coast Customers Group as this region is no longer supported in their store // Custom class is query indexed through the NCache Management Center or config.ncconf*/ // Create SQL Query with the specified criteria // Make sure to use the Fully Qualified Name (FQN) string query = "DELETE FROM Alachisoft.NCache.Samples.Data.Customer WHERE $Group$ = ?"; // Use QueryCommand for query execution var queryCommand = new QueryCommand(query); // Providing parameters for query queryCommand.Parameters.Add("$Group$", "West Coast Customers"); // 'rowsAffected' number of items removed from cache int rowsAffected = cache.SearchService.ExecuteNonQuery(queryCommand); if (rowsAffected==0) Console.WriteLine($"No west coast customers removed");
To ensure the operation is fail-safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
In order to get more detail on object queries please refer to the SQL Reference for NCache section.
NCache provides sample application for Groups on GitHub.