@Override
  public void init(String query, JobConf conf) {
    super.init(query, conf);
    configMatches = HiveConf.getBoolVar(conf, HiveConf.ConfVars.HIVE_MAPSIDE_AGGREGATE);
  }
Detects out-of-memory errors when hash tables in map-based aggregation group
by queries take up too much memory.

Conditions to check

1. The query contains a group by.
2. Map-side aggregation is turned on.
3. There is a out of memory exception in the log.
ql/src/java/org/apache/hadoop/hive/ql/exec/errors/MapAggrMemErrorHeuristic.java