常用视图在12c中已被替换
坏块：v$database_block_corruption ----> v$nonlogged_block
闪回区：V$FLASH_RECOVERY_AREA_USAGE ----> V$RECOVERY_AREA_USAGE
dg状态：v$managed_standby ----> v$dataguard_process;
19c 中不被支持的参数：
SELECT name from v$parameter WHERE isdeprecated = 'TRUE' ORDER BY name;
NAME
---------------------------------
active_instance_count
asm_preferred_read_failure_groups
background_dump_dest <---------- 10g 常用
buffer_pool_keep <---------- 偶尔用
buffer_pool_recycle
cluster_database_instances
commit_write
cursor_space_for_time
db_block_buffers
fast_start_io_target
instance_groups
lock_name_space
log_archive_start
parallel_adaptive_multi_user
plsql_debug
plsql_v2_compatibility
rdbms_server_dn
remote_os_authent
resource_manager_cpu_allocation
sec_case_sensitive_logon
serial_reuse
sql_trace
unified_audit_sga_queue_size
user_dump_dest
24 rows selected.
21c开始一些值得注意的不再支持特性：
相关视图、参数也不建议使用：
安全检查的脚本该更新了
参考：
https://docs.oracle.com/en/database/oracle/oracle-database/21/upgrd/behavior-changes-deprecated-desupport-oracle-database.html#GUID-3BAFD95E-4D00-4F0F-BC80-6064F497F878