Configure Searchable Attributes for Data Structures in Cache

Note

This feature is only available in NCache Enterprise Edition.

A Data type can also be associated with searchable attributes such as:

Groups
Tags
Named Tags

These searchable attributes can be used to query all associated items, as explained in Querying Data Structures. For example, a CacheItem and HashSet can belong to the same group. These attributes are specified using the DataTypeAttributes class.

Warning

These attributes can not be modified once a data type is created, however the data type itself can be modified.

Pre-requisites

Include the following namespaces in your application:
- Alachisoft.NCache.Client.DataTypes
- Alachisoft.NCache.Client
- Alachisoft.NCache.Runtime.Exceptions
The application must be connected to cache before performing the operation.
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.

The following code sample creates a HashSet ProductIDSet of int type and specifies group Electronics, tags and a Named Tag to it using DataTypeAttributes. ProductIDs are then fetched and added to this HashSet. You can query on these set values.

Tip

One quick way to verify whether data type has been created is to use either properties of the Cache class:

Count returns the number of items present in the cache.
Contains verifies if the specified key of the data type exists in the cache.

try
{
    // Pre-condition: Cache must be connected

    // Specify unique cache key for set
    string key = "ProductIDSet";

    // Specify attributes for hashset
    var attributes = new DataTypeAttributes();

    // Specify group "Electronics"
    attributes.Group = "Electronics";

    // Specify tags
    Tag[] tags = new Tag[2];
    tags[0] = new Tag("2 Year Warranty");
    tags[1] = new Tag("Stainless Steel");
    attributes.Tags = tags;

    // Specify Named Tag
    var namedTag = new NamedTagsDictionary();
    namedTag.Add("Discount", 0.4);
    attributes.NamedTags = namedTag;

    // Create hashset with attributes
    IDistributedHashSet<int> hashSet = 
                cache.DataTypeManager.CreateHashSet<int>(key, attributes);

    // Adding Product IDs to Set
    int[] productIDs = FetchProductIDs();

    foreach(var productID in productIDs)
    {
        // Add product IDs to set
        hashSet.Add(productID);
    }

    // You can query on this hashset using these attributes

    // Check if the hashset exists in cache
    // using cache.Contains() or cache.Count
}
catch (OperationFailedException ex)
{
    // NCache specific exception

    if(ex.ErrorCode == NCacheErrorCodes.KEY_ALREADY_EXISTS)
    {       
        // An item with the same key already exists
    }
    else if (ex.ErrorCode == NCacheErrorCodes.CACHEITEM_IN_DATA_STRUCTURES)
    {
        // Data structures cannot be of CacheItem type
        // CacheItems cannot be added in data structures
    }
    else
    {
        // NCache specific exception
        // Exception can occur due to:
        // Connection Failures
        // Operation Timeout
        // Operation performed during state transfer
    }
}
catch (Exception ex)
{
    // Any generic exception like ArgumentNullException or ArgumentException
}

Recommendation: To ensure the operation is fail safe, it is recommended to handle any potential exceptions within your application, as explained in Handling Failures.

Configure Searchable Attributes for Data Structures in Cache

Note

Warning

Pre-requisites

Tip

See Also