Delete Group Data in Cache with SQL

Note

This feature is only available in NCache Enterprise Edition.

Similar to searching with SQL, NCache provides object queries through which you use a criteria given in a query delete result sets. To delete the data in 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.

ExecuteNonQuery processes the query on the server-side and then sends the result to the client in the tabular form to ICacheReader type of instance.

Prerequisites

Install the following NuGet package in your application:
- Enterprise: Alachisoft.NCache.SDK
Include the following namespaces in your application:
- Alachisoft.NCache.Client
- Alachisoft.NCache.Runtime
Cache must be running.
The application must be connected to cache before performing the operation.
Custom classes/searchable attributes must be indexed as explained in Configuring Query Indexes.
Make sure that the data being added is serializable.
For API details refer to: ICache, ICacheReader, QueryCommand, ExecuteNonQuery
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

Add the following Maven dependencies in your pom.xml file:

<dependency>
    <groupId>com.alachisoft.ncache</groupId>
    <artifactId>ncache-client</artifactId>
    <version>x.x.x</version>
</dependency>

Include the following packages in your application:
- import com.alachisoft.ncache.client.*;
- import com.alachisoft.ncache.runtime.exceptions.*;
Cache must be running.
The application must be connected to cache before performing the operation.
Custom classes/searchable attributes must be indexed as explained in Configuring Query Indexes.
Make sure that the data being added is serializable.
For API details refer to: Cache, CacheReader, executeNonQuery
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

Install and include the following module in your application:
- Enterprise: const ncache = require('ncache-client')
Cache must be running.
The application must be connected to cache before performing the operation.
Custom classes/searchable attributes must be indexed as explained in Configuring Query Indexes.
For API details refer to: Cache, executeNonQuery
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

Install the NCache Python client by executing the following command:

# Enterprise Client
pip install ncache-client

Indexing for searchable objects and their attributes need to be configured first as explained in Configuring Query Indexes in Administrator's Guide.
Import the NCache module in your application.
Cache must be running.
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

Add the following Maven dependencies in your pom.xml file:

<dependency>
    <groupId>com.alachisoft.ncache</groupId>
    <artifactId>ncache-scala-client</artifactId>
    <version>x.x.x</version>
</dependency>

Indexing for searchable objects and their attributes need to be configured first as explained in Configuring Query Indexes in Administrator's Guide.
Import the following packages in your application:
- import com.alachisoft.ncache.scala.client.*;
Cache must be running.
The application must be connected to cache before performing the operation.
Make sure that the data being added is serializable.
To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.
To handle any unseen exceptions, refer to the Troubleshooting section.

Delete Group

Given a certain criteria, you can search for groups present in the cache with SQL queries. The following program searches for a group against a certain Customer ID through SQL query i.e. the group that the Customer ID belongs to.

try
{
    // Pre-conditions: Cache is already connected
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Create SQL Query with the specified criteria
    // Make sure to use the Fully Qualified Name (FQN)
    string query = "DELETE FROM FQN.Customer WHERE $Group$ = ?";

    // Use QueryCommand for query execution
    var queryCommand = new QueryCommand(query);

    queryCommand.Parameters.Add("$Group$","ImportantCustomers");

    // rowsAffected is the number of items removed from cache
    int rowsAffected = cache.SearchService.ExecuteNonQuery(queryCommand);
}
catch (OperationFailedException ex)
{
    if (ex.ErrorCode == NCacheErrorCodes.INCORRECT_FORMAT)
    {
        // Make sure that the query format is correct
    }
    else
    {
        // Exception can occur due to:
        // Connection Failures 
        // Operation Timeout
        // Operation performed during state transfer    
    }
}
catch (Exception ex)
{
    // Any other generic exception like ArgumentNullException or ArgumentException
}

try
{
    // Pre-conditions: Cache is already connected
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Create SQL Query with the specified criteria
    // Make sure to use the Fully Qualified Name (FQN)
    String query = "DELETE FROM FQN.Customer WHERE $Group$ = ?";

    // Use QueryCommand for query execution
    QueryCommand queryCommand = new QueryCommand(query);

    queryCommand.getParameters().put("$Group$","ImportantCustomers");

    // rowsAffected is the number of items removed from cache
    int rowsAffected = cache.getSearchService().executeNonQuery(queryCommand);
}
catch (OperationFailedException ex)
{
    if (ex.getErrorCode() == NCacheErrorCodes.INCORRECT_FORMAT)
    {
        // Make sure that the query format is correct
    }
    else
    {
        // Exception can occur due to:
        // Connection Failures
        // Operation Timeout
        // Operation performed during state transfer
    }
}
catch (Exception ex)
{
    // Any generic exception like NullPointerException or IllegalArgumentException
}

// This is an async method
try
{
    // Pre-conditions: Cache is already connected
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Create SQL Query with the specified criteria
    // Make sure to use the Fully Qualified Name (FQN)
    var query = "DELETE FROM FQN.Customer WHERE $Group$ = ?";

    // Use QueryCommand for query execution
    var queryCommand = new ncache.QueryCommand(query);

    var parameters = this.map.set("$Group","Important Customers");
    queryCommand.setParameters(parameters);

    var searchService = await this.cache.getSearchService();

    // rowsAffected is the number of items removed from cache
    var rowsAffected = await searchService.executeReader(queryCommand);
}
catch(error)
{
   // Handle errors
}

try:
    # Pre-conditions: Cache is already connected
    # Custom class is query indexed through NCache Web Manager or config.ncconf

    # Create SQL Query with the specified criteria
    # Make sure to use the Fully Qualified Name(FQN)
    query = "DELETE FROM FQN.Customer WHERE $Group$ = ?"

    # Use QueryCommand for query execution
    query_command = ncache.QueryCommand(query)

    parameters = {"$Group": "Important Customers"}
    query_command.set_parameters(parameters)

    search_service = cache.get_search_service()

    # rows_affected is the number of items removed from cache
    rows_affected = search_service.execute_non_query(query_command)

except Exception as exp:
    # Handle errors

try {
    // Pre-conditions: Cache is already connected
    // Custom class is query indexed through NCache Web Manager or config.ncconf

    // Create SQL Query with the specified criteria
    // Make sure to use the Fully Qualified Name (FQN)
    val query = "DELETE FROM FQN.Customer WHERE $Group$ = ?"

    // Use QueryCommand for query execution
    val queryCommand = new QueryCommand(query)

    queryCommand.setParameters(Map("$Group$" -> "ImportantCustomers"))

    // rowsAffected is the number of items removed from cache
    val rowsAffected = cache.getSearchService.executeNonQuery(queryCommand)
}
catch {
    case exception: Exception => {
      // Handle any errors
    }
}

Recommendation: 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.

Additional Resources

NCache provides sample application for Groups on GitHub.

Delete Group Data in Cache with SQL

Note

Prerequisites

Delete Group

Additional Resources

See Also