KYLIN-1186, we've gained the ability to count distinct Int type columns precisely.
However, the implements of
KYLIN-1186 is not stable, especially in 2.x-staging branch.
The reason is that the measure's maxlength is used to allocate memory in 2.x version, and the BitmapMeasure is hardcoded to 8MB in
KYLIN-1186, causing OOM when cube building.
To resolve this problem, we have introduce precision on the bitmap measure, such as bitmap(100), bitmap(10000), bitmap(1000000), meaning the measure could accept 100/10000/1M cardinality at most. This solution should be fine, considering the reality, if the count value over 1000000, the hyperloglog measure which produce approx. result should be acceptable.