Method Aggregate

Aggregate(IValueExtractor, IAggregator, IKeyFilter, QueryCommand, Int32)

Built upon MapReduce framework, processes distributed data records to return compiled and statistical results for analytical purposes.

Declaration

object Aggregate(IValueExtractor extractor, IAggregator aggregator, IKeyFilter keyFilter = null, QueryCommand queryCommand = null, int timeout = null)

Parameters

Type	Name	Description
IValueExtractor	extractor	Implementation of IValueExtractor to extract the meaningful attributes from given objects.
IAggregator	aggregator	IAggregator For actual grouping and analytical operations on given data using Map Reduce Combiner and Reducer.
IKeyFilter	keyFilter	Instance of IKeyFilter implementation.
QueryCommand	queryCommand	Instance of QueryCommand containing query and values.
System.Int32	timeout	Time in millisecond in which if result is not returned, thread will be terminated and exception or null will be given.

Returns

Type	Description
System.Object	Returns a single result depending upon given extractor.

Remarks

Aggregator can perform following operations Average, Sum, Min, Max, Count, Distinct. If result after aggregation execution is null than default value of built in Aggregator for that specific type is returned. User can also implement custom aggregator, as well as aggregator for custom data types and also for custom functions like Mean, Median, Mode.

Examples

ICache cache = CacheManager.GetCache("myCache");

string key1 = "2202";

Product product1 = new Product()
{
    Id = 4,
    Category = "Clothes",
    UnitPrice = 4,
    UnitsAvailable = 2
};

string key2 = "2203";
Product product2 = new Product()
{
    Id = 4,
    Category = "Shoes",
    UnitPrice = 5,
    UnitsAvailable = 9
};

cache.Add(key1, product1);
cache.Add(key2, product2);

string query = "SELECT Alachisoft.NCache.Sample.Data.Product WHERE this.Category=?";
QueryCommand queryCommand = new QueryCommand(query);
queryCommand.Parameters.Add("Category", "Clothes");

object result = cache.ExecutionService.Aggregate(new BasicTypeExtractor(), BuiltInAggregator.Count(), null, queryCommand, 50000);