commit 8b2aceeb97c8f89f2898c0b35f38cc36d3cdda63
author Taewoo Kim <wangsaeu@yahoo.com> Wed Jan 04 12:44:02 2017 -0800
committer Taewoo Kim <wangsaeu@yahoo.com> Wed Jan 04 15:45:58 2017 -0800
tree cba219e154ed7760cc89d798777cc728eb9836f2
parent 1355c269f50e84087ed24cb0ec9f091d2ce19a5a

ASTERIXDB-1556, ASTERIXDB-1733: Hash Group By and Hash Join conform to the memory budget

 - External Hash Group By and Hash Join now conform to the memory budget (compiler.groupmemory and compiler.joinmemory)
 - For Optimzed Hybrid Hash Join, we calculate the expected hash table size when the build phase is done and
   try to spill one or more partitions if the freespace can't afford the hash table size.
 - For External Hash Group By, the number of hash entries (hash table size) is calculated based on
   an estimation of the aggregated tuple size and possible hash values for the given field size in that tuple.
 - Garbage Collection feature has been added to SerializableHashTable. For external hash group-by,
   whenever we spill a data partition to the disk, we also check the ratio of garbage in the hash table.
   If it's greater than the given threshold, we conduct a GC on Hash Table.

Change-Id: I2b323e9a2141b4c1dd1652a360d2d9354d3bc3f5
Reviewed-on: https://asterix-gerrit.ics.uci.edu/1056
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
BAD: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Integration-Tests: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Yingyi Bu <buyingyi@gmail.com>