지도 및 튜플 값 (일일 평균)으로 Cassandra UDA 함수에서 튜플 값을 인스턴스화합니다.

Question

나는 (다음에 평균을 계산하기 위해) 날짜별로 값을 계산하고 합계하는 함수를 작성하려고합니다. 나는 이것을 멀리 가지고있다 :

CREATE OR REPLACE FUNCTION state_group_count_and_sum(state map<timestamp, frozen<tuple<bigint,double>>>, timestamp timestamp, value double) 
CALLED ON NULL INPUT 
RETURNS map<timestamp, frozen<tuple<bigint,double>>> 
LANGUAGE java AS ' 
Date date = (Date) timestamp; 
Calendar cal = Calendar.getInstance(); // locale-specific 
cal.setTime(date); 
cal.set(Calendar.HOUR_OF_DAY, 0); 
cal.set(Calendar.MINUTE, 0); 
cal.set(Calendar.SECOND, 0); 
cal.set(Calendar.MILLISECOND, 0); 
date = cal.getTime(); 

TupleValue tupleValue = state.get(date); 

Long count = (Long) tupleValue.getLong(0); 
if (count == null) count = 1L; 
else count = count + 1L; 

Double sum = (Double) tupleValue.getDouble(1); 
if (sum == null) sum = value; 
else sum = sum + value; 

//if (tupleValue == null) ? 
tupleValue.setLong(0, count); 
tupleValue.setDouble(1, sum); 
state.put(date, tupleValue); 
return state; ' ; 

CREATE OR REPLACE AGGREGATE group_count_and_sum(timestamp, double) 
SFUNC state_group_count_and_sum 
STYPE map<timestamp, frozen<tuple<bigint,double>>> 
INITCOND {}; 

tupleValue가 맵에 아직없는 새 날마다 null이기 때문에 실패한다. 어떻게하면 UDA에서 튜플 값을 인스턴스화 할 수 있습니까?

Answer 1

수정 됨.

CREATE OR REPLACE FUNCTION state_group_count_and_sum(state map<timestamp, frozen<tuple<bigint,double>>>, timestamp timestamp, value double) 
CALLED ON NULL INPUT 
RETURNS map<timestamp, frozen<tuple<bigint,double>>> 
LANGUAGE java AS ' 
Date date = (Date) timestamp; 
Calendar cal = Calendar.getInstance(); // locale-specific 
cal.setTime(date); 
cal.set(Calendar.HOUR_OF_DAY, 0); 
cal.set(Calendar.MINUTE, 0); 
cal.set(Calendar.SECOND, 0); 
cal.set(Calendar.MILLISECOND, 0); 
date = cal.getTime(); 

TupleValue tupleValue = state.get(date); 
if (tupleValue == null) { 
com.datastax.driver.core.TupleType tupleType = com.datastax.driver.core.TupleType.of(com.datastax.driver.core.ProtocolVersion.NEWEST_SUPPORTED, com.datastax.driver.core.CodecRegistry.DEFAULT_INSTANCE, com.datastax.driver.core.DataType.bigint(), com.datastax.driver.core.DataType.cdouble()); 
tupleValue = tupleType.newValue(0L, 0.0); 
} 

Long count = (Long) tupleValue.getLong(0); 
if (count == null) count = 1L; 
else count = count + 1L; 

Double sum = (Double) tupleValue.getDouble(1); 
if (sum == null) sum = value; 
else sum = sum + value; 

tupleValue.setLong(0, count); 
tupleValue.setDouble(1, sum); 
state.put(date, tupleValue); 
return state; ' ; 

CREATE OR REPLACE AGGREGATE group_count_and_sum(timestamp, double) 
SFUNC state_group_count_and_sum 
STYPE map<timestamp, frozen<tuple<bigint,double>>> 
INITCOND {};