Thanks Yang's great work!
在 2015年12月08日 17:47, Li Yang 写道:
This is a bump of KYLIN-976 in case you are not yet aware...
KYLIN-976 is a refactoring of how Kylin works with aggregation and aims to
allow adding custom aggregation types easily.
Kylin started with basic support of SUM, COUNT, MAX, MIN, AVG (from sum and
count), and COUNT_DISTINCT (based on hyperloglog). Later TopN is added in
2.x branch. And the list is growing for sure. Xiaoyu is working on storing
raw records as a special type of measure (KYLIN-1122), also Yerui is
working on precise count distinct using bitmap (KYLIN-1186).
The possibility is unlimited. Implement a domain specific aggregation is
now quite easy. E.g. aggregate user events to detect time serials or access
patterns. Or draw a sketch of certain user groups. Or pre-calculate
clusters of data points. Or histogram... Use your imagination.
Whoever interested can peek at MeasureTypeFactory and MeasureType on 2.x
branch. The API may still change, but at the same time is stable enough for
pilots. The javadoc should get you started. HLLCMeasureType and
TopNMeasureType are two good examples.
Cheers
Yang
