Calculating Total Instance Memory Footprint

Since the PGA (controlled by the ‘pga_aggregate_target’ setting) is outside of the SGA, this query will calculate the combined totals.  The amount of free RAM on the DB host should exceed this calculated total:

  with counts as (
    select round(sum(value)/1024/1024) total from v$sga
    union all
    select value/1024/1024 from v$parameter where name = 'pga_aggregate_target')
  select sum(total) from counts;