Search notes:

Oracle: V$SGA

v$sga: how much memory does the SGA (System Global Area) use?

select * from v$sga is roughly the same as typing show sga in SQL*Plus with the exception that the latter also shows the total.

select
  name
from
  v$sga
order by
  name;
--
-- Fixed Size
-- Variable Size
-- Database Buffers
-- Redo Buffers

See also