Aggregate (Field Expression)

The AggregateExpression   class allows performing aggregation over a multi-valued numeric FieldExpression. 

*Available Functions (See here ):*

• AVG - computes the average over a multi-value field/expression
• MIN - computes the minimum value over a multi-value field/expression
• MAX - computes the maximum value over a multi-value field/expression
• SUM - computes the sum over a multi-value field/expression
• STDEV - computes the standard deviation over a multi-value field/expression
• COUNT - counts the number of values in a multi-value field/expression
• FIRST - returns the first value for a multi-value field/expression
• LAST - returns the last value for a multi-value field/expression
• DISTINCT - returns only the unique values for a multi-value field/expression

Example:

// Compute the average over all field values
// Assumes the "value" field is a numeric multi-value field
QueryRequest request = new QueryRequest("*:*");
request.addField( new AggregateExpression(AggregateExpression.AVG, new StoredField("temperatures")) );
// ... (Perform Search)

REST Syntax:

Example:

# Compute a bunch of aggregation functions over a multi value field
# Assumes the "value" field is a numeric multi-value field
&fields=AVG(value),MIN(value),MAX(value),SUM(value),STDEV(value),COUNT(value),FIRST(value),LAST(value)