Note
This feature is only available in the NCache Enterprise Edition.
A data structure can also be associated with the searchable attributes such as:
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.
Important
These attributes can not be modified once a data structure is created. However, the data structure itself can be modified.
Prerequisites
- 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.
- For API details, refer to: ICache, DataTypeAttributes, NamedTagsDictionary, Tag, Group, NamedTags, IDistributedHashSet, DataTypeManager, CreateHashSet, Contains, Count.
- 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.
- For API details, refer to: Cache, DataStructureAttributes, setGroup, Tag, setTags, DistributedHashSet, NamedTagsDictionary, setNamedTags, getDataStructuresManager, createHashSet, contains, getCount.
- 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.
- For API details, refer to: Cache, DataStructureAttributes, setGroup, NamedTagsDictionary, Tag, setNamedTags, getDataStructuresManager, createList, contains, getCount.
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 also query on these set values.
Tip
One quick way to verify whether a data structure 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 structure 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 HashSet
int[] productIDs = FetchProductIDs();
foreach(var productID in productIDs)
{
// Add product IDs to HashSet
hashSet.Add(productID);
}
// You can also query on this HashSet using these attributes
}
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
}
try {
// Pre-condition: Cache must be connected
// Specify unique cache key for set
String key = "ProductIDSet";
// Specify attributes for HashSet
var attributes = new DataStructureAttributes();
// Specify group "Electronics"
attributes.setGroup("Electronics");
// Specify tags
Tag[] tags = new Tag[2];
tags[0] = new Tag("2 Year Warranty");
tags[1] = new Tag("Stainless Steel");
attributes.setTags(Arrays.asList(tags));
// Specify Named Tag
var namedTag = new NamedTagsDictionary();
namedTag.add("Discount", 0.4);
attributes.setNamedTags(namedTag);
var writeThruOptions = null;
// Create HashSet with attributes
DistributedHashSet hashSet = cache.getDataStructuresManager().createHashSet(key, attributes, writeThruOptions, Integer.class);
// Adding Product IDs to HashSet
int[] productIDs = fetchProductIDs();
for (var productID : productIDs) {
// Add product IDs to HashSet
hashSet.add(productID);
}
// You can query on this HashSet using these attributes
} catch (OperationFailedException ex) {
// NCache specific exception
if (ex.getErrorCode() == NCacheErrorCodes.KEY_ALREADY_EXISTS) {
// An item with the same key already exists
} else if (ex.getErrorCode() == 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 IllegalArgumentException or NullPointerException
}
try {
import java.util
// Pre-condition: Cache must be connected// Pre-condition: Cache must be connected
// Specify unique cache key for set
val key = "ProductIDSet"
// Specify attributes for hashset
val attributes = new DataStructureAttributes
// Specify group "Electronics"
attributes.setGroup("Electronics")
// Specify tags
val tags = List(Tag("2 Year Warranty"), Tag("Stainless Steel"))
attributes.setTags(tags)
// Specify Named Tag
val namedTag = new NamedTagsDictionary
namedTag.add("Discount", 0.4)
attributes.setNamedTags(namedTag)
val writeThruOptions = null
// Create hashset with attributes
val hashSet = cache.getDataStructuresManager.createHashSet(key, attributes, writeThruOptions, classOf[String])
// Adding Product IDs to Set
val productIDs = fetchProductIDs
for (productID <- productIDs) { // Add product IDs to set
hashSet.add(productID)
}
// You can query on this hashset using these attributes
}
catch {
case exception: Exception => {
// Handle any errors
}
}
// This is an async method
try {
// Pre-condition: Cache must be connected
// Specify unique cache key for HashSet
var key = "ProductIDSet";
// Specify attributes for HashSet
var attributes = new ncache.DataStructureAttributes();
// Specify group "Electronics"
attributes.setGroup("Electronics");
// Specify tags
var tags = [
new ncache.Tag("2 Year Warranty"),
new ncache.Tag("Stainless Steel"),
];
attributes.setTags(tag);
// Specify Named Tag
var namedTag = new ncache.NamedTagsDictionary();
namedTag.add("Discount", 0.4);
attributes.setNamedTags(namedTag);
// Create list with attributes
var list = await (
await this.cache.getDataStructuresManager()
).createList(key, Number(), attributes, null);
// Adding Product IDs to HashSet
var productIDs = this.fetchProductIDs();
for (var productID in productIDs) {
// Add product IDs to HashSet
list.add(productID);
}
// You can query on this list using these attributes
} catch (error) {
// Handle errors
}
try:
# Pre-condition: Cache must be connected
# Specify unique cache key for set
key = "ProductIDSet"
# Specify attributes for hashset
attributes = DataStructureAttributes()
# Specify group "Electronics"
attributes.set_group("Electronics")
# Specify tags
tags = [ncache.Tag("2 Year Warranty"), ncache.Tag("Stainless Steel")]
attributes.set_tags(tags)
# Specify Named Tag
named_tag = ncache.NamedTagsDictionary()
named_tag.add("Discount", 0.4)
attributes.set_named_tags(named_tag)
# Create list with attributes
attr_list = cache.get_data_structures_manager().create_list(key, int, attributes)
# Adding Product IDs to Set
product_ids = fetch_product_ids()
for product_id in product_ids:
# Add product IDs to set
attr_list.add(product_id)
# You can query on this list using these attributes
except Exception as exp:
# Handle errors
Note
To ensure that 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 a sample application for configuring searchable attributes with data structures on
GitHub.
See Also
Using Counter in Cache
Configure Invalidation Attributes
Query on Data Structures
Remove Data Structure from Cache