* Refactoring Appenderator
1) Added publishExecutor and handoffExecutor for background publishing and handing segments off
2) Change add() to not move segments out in it
* Address comments
1) Remove publishTimeout for KafkaIndexTask
2) Simplifying registerHandoff()
3) Add increamental handoff test
* Remove unused variable
* Add persist() to Appenderator and more tests for AppenderatorDriver
* Remove unused imports
* Fix strict build
* Address comments
* Add SameIntervalMergeTask for easier usage of MergeTask
* fix a bug and add ut
* remove same_interval_merge_sub from Task.java and remove other no needed code
* ability to not rollup at index time, make pre aggregation an option
* rename getRowIndexForRollup to getPriorIndex
* fix doc misspelling
* test query using no-rollup indexes
* fix benchmark fail due to jmh bug
To bring consistency to docs and source this commit changes the default
values for maxRowsInMemory and rowFlushBoundary to 75000 after
discussion in PR https://github.com/druid-io/druid/pull/2457.
The previous default was 500000 and it's lower now on the grounds that
it's better for a default to be somewhat less efficient, and work,
than to reach for the stars and possibly result in
"OutOfMemoryError: java heap space" errors.
Jihoon Son
kaijianding
David Lim
Gian Merlino
Dave Li
Björn Zettergren
fjy