Remove Cache Data with Tags

Note

This feature is only available in NCache Enterprise Edition.

The items which are added in the cache with particular tags can also be removed from the cache using the same tags. The user can remove tagged items along with their values from the cache.

Pre-Requisites

Install the following NuGet package in your application.
- Alachisoft.NCache.SDK
Include the following namespaces in your application:
- Alachisoft.NCache.Client
- Alachisoft.NCache.Runtime.Caching
- Alachisoft.NCache.Runtime.Exceptions
The application must be connected to cache before performing the operation.
Cache must be running.
Make sure that the data being added is serializable.
For API details refer to: ICache, Tag, RemoveByTag, RemoveBulk
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>5.2.0</version>
</dependency>

Import the following packages in your application:
- import com.alachisoft.ncache.client.*;
- import com.alachisoft.ncache.runtime.exceptions.*;
- import import com.alachisoft.ncache.runtime.caching.*;
The application must be connected to cache before performing the operation.
Cache must be running.
Make sure that the data being added is serializable.
For API details refer to: Cache, Tag, removeByTag, removeByTags, removeBulk())
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.

Include the following modules in your application:
- const ncache = require('ncache-client')
The application must be connected to cache before performing the operation.
Cache must be running.
For API details refer to: Cache, Tag, removeByTag, removeByTags, removeBulk()
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.

Remove Tagged Data from Cache

Similar to retrieving items using tags, tagged data can be removed using either RemoveByTag, RemoveByAnyTag or RemoveByAllTags method. These methods are then explained below.

Note

These three APIs do not return anything after removal.

RemoveByTag

RemoveByTag is a method in which a single tag is provided and the items associated with that particular tag are removed from the cache. In case of Java, removeByTag method is used for this purpose in case of Java.

The following example removes the cache items associated with the tag Important Customers.

Tip

One quick way to verify successful removal of items from the cache is to check the item count by using the Count property of the cache before and after performing the operation.

Warning

Providing Null tag array will throw an ArgumentNullException or NullPointerException.

try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Cache items containing the tag 'Important Customers' are removed from the cache
    cache.SearchService.RemoveByTag(tags[0]);
}
catch (OperationFailedException ex)
{
    // 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-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Cache items containing the tag 'Important Customers' are removed from the cache
    cache.getSearchService().removeByTag(productTags[0]);
}
catch (Exception ex) 
{
    // Exception can occur due to:
    // Connection Failures
    // Operation Timeout
    // Operation performed during state transfer
    // Any generic exception
}

// This is an async method
try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    var tags = new ncache.Tag[2];
    tags[0] = new ncache.Tag("Important Customers");
    tags[1] = new ncache.Tag("East Coast Customers");

    // Cache items containing the tag 'Important Customers' are removed from the cache

    var searchService = await this.cache.getSearchService();
    var keys = await searchService.removeByTag(tags[0]);
}
catch(error)
{
    // Handle 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.

RemoveByAnyTag

RemoveByTag is a method and ByAnyTag is the search option in which a tag list of multiple tags is provided and the items containing ANY of the tags are removed from the cache. For Java, the method used for this purpose is removeByAnyTag.

The following example removes the items from the cache containing any tag from the list tags.

Tip

One quick way to verify successful removal of items from the cache is to check the item count by using the Count property of the cache before and after performing the operation.

Warning

Providing Null tag list will throw an ArgumentNullException or NullPointerException.

try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Cache items containing any of the tags are removed from the cache
    cache.SearchService.RemoveByTags(tags, TagSearchOptions.ByAnyTag);
}
catch (OperationFailedException ex)
{
    // 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-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Cache items containing any of the tags are removed from the cache
    cache.getSearchService().removeByTags(tags, ByAnyTag);
}
catch (Exception ex) 
{
    // Exception can occur due to:
    // Connection Failures
    // Operation Timeout
    // Operation performed during state transfer
    // Any generic exception
}

// This is an async method
try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    var tags = new ncache.Tag[2];
    tags[0] = new ncache.Tag("Important Customers");
    tags[1] = new ncache.Tag("East Coast Customers");

    // Cache items containing the tag 'Important Customers' are removed from the cache
    var searchService = await this.cache.getSearchService();
    var keys = await searchService.removeByTags(tags,ncache.TagSearchOptions.ByAnyTags);
}
catch(error)
{
    // Handle 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.

RemoveByAllTags

RemoveByTag is a method and ByAllTags is the search option in which a tag list of multiple tags is provided and the items containing ALL of the tags are removed from the cache. In java, removeByAllTags is used for removing the items matching all the tags provided.

The following example removes the items from the cache containing all tags from the list tags.

Tip

One quick way to verify successful removal of items from the cache is to check the item count by using the Count property of the cache before and after performing the operation.

Warning

Providing Null tag list will throw an ArgumentNullException or NullPointerException.

try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Cache items containing the tag 'Important Customers' are removed from the cache
    cache.SearchService.RemoveByTags(tags, TagSearchOptions.ByAllTags);

}
catch (OperationFailedException ex)
{
    // 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-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Cache items containing all the tags are removed from the cache
     cache.getSearchService().removeByTags(tags,ByAllTags);
}
catch (Exception ex) 
{
    // Exception can occur due to:
    // Connection Failures
    // Operation Timeout
    // Operation performed during state transfer
    // Any generic exception
}

// This is an async method
try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    var tags = new ncache.Tag[2];
    tags[0] = new ncache.Tag("Important Customers");
    tags[1] = new ncache.Tag("East Coast Customers");

    // Cache items containing the tag 'Important Customers' are removed from the cache
    var searchService = await this.cache.getSearchService();
    var keys = await searchService.removeByTags(tags,ncache.TagSearchOptions.ByAllTags);
}
catch(error)
{
    // Handle 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.

Remove Cached Data by Retrieving Keys

Another approach to remove tagged data items is by first retrieving the keys using tags and then by removing them using the RemoveBulk API. The advantage of using this approach is that the successfully removed items are returned after the removal whereas the RemoveByTag method does not return anything.

Warning

This method is not a recommended approach as it increases the network calls which is not efficient for the user.

The following example retrieves the keys from the cache containing the specific tag using the GetKeysByTag method. You can use any of the three methods for retrieving the keys discussed in the Retrieve Items with Tag. The retrieved keys are then removed along with the values from the cache.

// PreCondition: Tag is created and associated with an item
try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Keys with the Tag 'ImportantCustomers' are retrieved
    // Retrieved Cache keys are then returned to an ICollection
    ICollection<string> keys = cache.SearchService.GetKeysByTags(tags, TagSearchOptions.ByAllTags);

    // Checks the key Count
    if (keys.Count > 0)
    {
        // Create dictionary to store removed items
        IDictionary<string, Customer> removedItems = new Dictionary<string,Customer>();

        // Remove items
        cache.RemoveBulk(keys, out removedItems);
    }
    else
    {
        // No key exists in the cache
    }
}
catch (OperationFailedException ex)
{
    // 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
}

// PreCondition: Tag is created and associated with an item
try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("Important Customers");
    tags[1] = new Tag("East Coast Customers");

    // Keys with the Tag 'ImportantCustomers' are retrieved
    // Retrieved Cache keys are then returned to an ICollection
    Collection<String> keys = cache.getSearchService().getKeysByTags(tags, TagSearchOptions.ByAllTags);

    // Checks the key Count
    if (keys.Count > 0)
    {
        // Create hashmap to store removed items
        Map<String, Customer> removedItems = new HashMap<String,Customer>();

        // Remove items
        cache.removeBulk(keys, removedItems);
    }
    else
    {
        // No key exists in the cache
    }
}
catch (OperationFailedException ex)
{
    // 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
// PreCondition: Tag is created and associated with an item
try
{
    // Pre-condition: Cache is already connected

    // Following tags are created and item is added in the cache with these tags
    var tags = new ncache.Tag[2];
    tags[0] = new ncache.Tag("Important Customers");
    tags[1] = new ncache.Tag("East Coast Customers");

    // Keys with the Tag 'ImportantCustomers' are retrieved
    // Retrieved Cache keys are then returned to an ICollection
    var searchService = await this.cache.getSearchService();
    var keys = await searchService.getKeysByTags(tags,ncache.TagSearchOptions.ByAllTags);

    // Checks the key Count
    if (keys.size() > 0)
    {
        // Create list to store removed items
        var removedItems = [];

        // Remove items
        this.cache.removeBulk(keys,removedItems);
    }
    else
    {
        // No key exists in the cache
    }
}
catch(error)
{
   // Handle 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.

Additional Resources

NCache provides sample application for Tags on GitHub.

Remove Cache Data with Tags

Note

Pre-Requisites

Remove Tagged Data from Cache

Note

RemoveByTag

Tip

Warning

RemoveByAnyTag

Tip

Warning

RemoveByAllTags

Tip

Warning

Remove Cached Data by Retrieving Keys

Warning

Additional Resources

See Also