[luciddb-users] Strange behaviour on SUM and SUM0

[Matthias D. W. <mwa...@ya...>]

Dear Farrago/LucidDB devs,

I think that I have discovered a bug (or at least some strange 
behaviour) in respect to the SUM and SUM0 aggregate functions. The 
problem consists in the fact that these functions do always operate with 
the datatype of the input (SQLSumAggFunction.java and 
SQLSumEmptyIsZeroAggFunction.java). This is not an issue for big 
integers or big floating point values but it turns out to be fatal when 
summing up rather small values (TINYINT, SMALLINT, FLOAT) which likely 
ends up in overflows.
Other database systems (eg. Postgres, 
http://www.postgresql.org/docs/8.2/static/functions-aggregate.html) 
perform implicit conversions to BIGINT, DOUBLE, NUMERIC before getting 
started.

Thanks,
Matthias Wallnöfer