Oracle Database 12c -- WRH$_LATCH_CHILDREN top consumer in SYSAUX

Problem

Objects WRH$_LATCH_CHILDREN_PK and WRH$_LATCH_CHILDREN takes considerable amount of space, and top space consumers of the SYSAUX tablespace, yet keep growing 

Solution

1) Check the statistics_level parameter, probably set to ALL. In this case huge amount of data being gathered and kept, and hence the objects' growth

Set the parameter to TYPICAL

alter system set statistics_level=typical scope=both;

2) AWR retention period. Large periods keep more data. Reduce the retention to the minimum required:

select * from dba_hist_wr_control 
where dbid = (select dbid from v$database);

declare
    p_retention_days number := 14;
    p_retention_minutes number := p_retention_days*24*60;
begin
    DBMS_WORKLOAD_REPOSITORY.MODIFY_SNAPSHOT_SETTINGS( 
        retention => p_retention_minutes 
    );   
end;

3) Purge old snapshots which fall outside the newly set retention policy:

Identify min and max snaphosts: 

select min(snap_id), max(snap_id)
from dba_hist_snapshot where dbid = (select dbid from v$database)
and end_interval_time < sysdate - 15;

Purge the snapshot range:

begin
DBMS_WORKLOAD_REPOSITORY.DROP_SNAPSHOT_RANGE(
   low_snap_id    =><min_snap_id>,
   high_snap_id   =><max_snap_id>);
end;