I was playing around in Hive (3, from HDP) with big integers when I noticed something weird:
select 9223372036854775807 * 9223372036854775807; -- 1 select 9223372036854775807 + 1; -- -9223372036854775808
It turns out that Hive silently overflows integers. This comes from java, which does the same.
It’s lucky I noticed, it could have been very painful for me down the line. The workaround is to use big decimal. As the doc says:
Integral literals larger than BIGINT must be handled with Decimal(38,0). The Postfix BD is required.
select 9223372036854775807BD * 9223372036854775807BD; -- 85070591730234615847396907784232501249 select 9223372036854775807BD + 1; -- 9223372036854775808
But it is still somewhat weird. Overflows with big decimals won’t error out but will return null:
select 9223372036854775807BD * 9223372036854775807BD * 9223372036854775807BD ; -- NULL
Furthermore, if the precision is not 0 some behaviours are not consistent:
create temporary table dec_precision( d decimal(38, 18) ); insert into dec_precision values (98765432109876543210.12345) , (98765432109876543210.12345) ; select sum(d) from dec_precision; -- NULL (but why?) select sum(98765432109876543210.12345BD) from dec_precision; -- 197530864219753086420.24690 (as expected) select 98765432109876543210.12345BD + 98765432109876543210.12345BD; -- 197530864219753086420.24690 (as expected)
select 9223372036854775807 * 9223372036854775807; -- ERROR 1690 (22003): BIGINT value is out of range in '9223372036854775807 * 9223372036854775807'
select 2147483647 * 2147483647; ERROR: integer out of range
are a lot safer and friendlier in that regard.