Pig sum fails with +ve and -ve values - hadoop

Question

I have below data
primary,first,second
1,393440.09,354096.08
1,4410533.33,3969479.99
1,-4803973.41,-4323576.07
I have to aggregate and sum first and second column. Below is the script I am executing
data_load= load <filelocation> using org.apache.pig.piggybank.storage.CSVExcelStorage(',', 'NO_MULTILINE', 'NOCHANGE', 'SKIP_INPUT_HEADER') As (primary:double, first:double,second:double)
dataAgrr = group data_load by primary;
sumData = FOREACH dataAgrr GENERATE
group as data,
SUM(data_load.first) as first,
SUM(data_load.second) as second,
SUM(data_load.primary) as primary;
After executing, below Output is produced:
(1.0,0.009999999951105565,-5.820766091346741E-11,3.0)
But when we manually adding second column (354096.08, 3969479.99, -4323576.07) gives 0.

Answer 1

Pig uses Java "double" internally.
Testing with a sample code below
import java.math.BigDecimal;
public class TestSum {
public static void main(String[] args) {
double d1 = 354096.08;
double d2 = 3969479.99;
double d3 = -4323576.07;
System.err.println("Total in double is " + ((d3 + d2 ) + d1));
BigDecimal bd1 = new BigDecimal("354096.08");
BigDecimal bd2 = new BigDecimal("3969479.99");
BigDecimal bd3 = new BigDecimal("-4323576.07");
System.err.println("Total in BigDecimal is " + bd3.add(bd2).add(bd1));
}
}
This produces
Total in double is -5.820766091346741E-11
Total in BigDecimal is 0.00
If you need a better precision, you may want to try using "bigdecimal" instead of "double" in your script.