Kylin doesn't need full segment scan. It only need scan one Cuboid (one combination of dimensions), which is a subset of a segment.
If there is "where" condition in query, Kylin will try to narrow down the scan key range with the given values, but this depends on the sequence of the dimension rows on rowkey (I think you can understand it). This is why the sequence of rowkey is so important for query performance. Besides, "where" conditions will be sent to HBaser coprocessor to do server side filtering. 2015-11-13 18:36 GMT+08:00 Sarnath <[email protected]>: > Hi All, > Does kylin perform full segment scans on certain GROUP BY followed by WHERE > clause? > This, I think, is because of rowkey hbase design. Can some1 confirm my > understanding? > Best, > Sarnath > -- Best regards, Shaofeng Shi
