There are A, B, C replicas of one tablet.
A has 0 - 10 version.
B has 0 - 5, 6, 7, 9, 10 version.
1. B has missed versions, so it clones 0 - 10 from A, and remove overlapped versions in its header.
2. Coincidentally, 6 is a version for delete predicate (delete where day = 20181221).
When removing overlapped versions, version 6 is removed but delete predicate is not be removed.
3. Unfortunately, 0-10 cloned from A has data indicated at 20181221.
4. B performs compaction, and data generated by 20181221 is be removed falsely.
* Add UserFunctionCache to cache UDF's library
This patch replace LibCache with UserFunctionCache. LibCache use HDFS
URL to identify a UDF's Library, and when BE process restart all of
downloaded library should be loaded another time. We use function id
corresponding to a library, and when process restart, all downloaded
libraries can be loaded without another downloading.
* update
