Aggregator[] aggregators = new Aggregator[len];
Expression[] expressions = new Expression[len];
SingleAggregateFunction[] functions = new SingleAggregateFunction[len];
for (int i = 0; i < aggregators.length; i++) {
SingleAggregateFunction aggFunc = (SingleAggregateFunction)ExpressionType.values()[WritableUtils.readVInt(input)].newInstance();
aggFunc.readFields(input, conf);
functions[i] = aggFunc;
aggregators[i] = aggFunc.getAggregator();
expressions[i] = aggFunc.getAggregatorExpression();
}
return new ServerAggregators(functions, aggregators,expressions, minNullableIndex);