DB SCATTERED READ - FULL TABLE SCAN
DB SEQUENTIAL REAL - IO
ENQUEUE - LOCKING
DB_16K_CACHE_SIZE, DB_8K_CACHE_SIZE, DB_2K_CACHE_SIZE
This parameter controls the maximum amount of memory PGA which can be used by the queries when WORKAREA_SIZE_POLICY is set to Auto.
The value you can be set in Bytes, kilobytes (K), megabytes (M) or gigabytes (G). The default value is 0
This parameter also has an effect on the execution plans of the cost based optimizer. The optimizer uses the value of the parameter PGA_AGGREGATE_TARGET to derive an estimate
for the minimum and maximum amount of memory which should be available at run-time for each sort, hash-join and bitmap operator in the query. Based on this minimum and maximum value, the
optimizer selects the best plan.
DBMS_STATS.GATHER_TABLE_STATS with GRANULARITY => 'PARTITION' OPTION
Wait is due to Data Guard Broker.