SQL> select banner from v$version where rownum=1;

BANNER
--------------------------------------------------------------------------------
Oracle Database 19c EE Extreme Perf Release 19.0.0.0.0 - Production

SQL> drop table t;

Table dropped.

SQL> create table t( i int primary key, v varchar2(1000)) segment creation immediate;

Table created.

SQL> create trigger tr_t before insert on t for each row begin null; end tr_t;
  2  /

Trigger created.

SQL> alter table t MEMOPTIMIZE for read;
alter table t MEMOPTIMIZE for read
*
ERROR at line 1:
ORA-62181: The MEMOPTIMIZE FOR READ feature is not supported on this table.


SQL> drop trigger tr_t;

Trigger dropped.

SQL> alter table t MEMOPTIMIZE for read;

Table altered.

SQL> create trigger tr_t before insert on t for each row begin null; end tr_t;
  2  /

Trigger created.

SQL> select MEMOPTIMIZE_READ  from user_tables where 'T'=table_name
  2  /

MEMOPTIM
--------
ENABLED

SQL>