在Oracle中，从9i开始引入了spfile，也就是服务 器端初始化参数，有很多是可以支持在线修改的，也就是修改会马上生效，详细内容看下面的说明：
The ISSYS_MODIFIABLE column in V$PARAMETER tells us whether the parameters are static or dynamic. Static parameters require the instance to be restarted while dynamic parameters can take effect（生效） immediately upon（在…之后） being changed.
SQL> select distinct issys_modifiable from v$parameter;
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ISSYS_MODIFIABLE
---------------------------
DEFERRED
FALSE
IMMEDIATE
If the ISSYS_MODIFIABLE value is set to FALSE for a parameter, it means that the parameter cannot change its value in the lifetime（一生） of the instance; the database needs to be restarted for changes to take effect（生效）.
A parameter set to IMMEDATE value means that it is dynamic（动态的） and can be set to change the present（当前） active instance as well as future database restarts.
A parameter set to DEFERRED is also dynamic, but changes only affect（生效） subsequent（后来的） sessions, currently active sessions will not be affected and retain（保持） the old parameter value.
举例如下：
SQL> select name,ISSYS_MODIFIABLE from v$parameter;
NAME ISSYS_MOD
---------------------------------------------------------------- ---------
tracefile_identifier FALSE
processes FALSE
sessions FALSE
timed_statistics IMMEDIATE
timed_os_statistics IMMEDIATE
resource_limit IMMEDIATE
license_max_sessions IMMEDIATE
license_sessions_warning IMMEDIATE
cpu_count FALSE
instance_groups FALSE
event FALSE
NAME ISSYS_MOD
---------------------------------------------------------------- ---------
shared_pool_size IMMEDIATE
sga_max_size FALSE
shared_pool_reserved_size FALSE
large_pool_size IMMEDIATE
java_pool_size FALSE
java_soft_sessionspace_limit FALSE
java_max_sessionspace_size FALSE
pre_page_sga FALSE
shared_memory_address FALSE
hi_shared_memory_address FALSE
use_indirect_data_buffers FALSE
NAME ISSYS_MOD
---------------------------------------------------------------- ---------
lock_sga FALSE
spfile FALSE
lock_name_space FALSE
enqueue_resources FALSE
trace_enabled IMMEDIATE
nls_language FALSE
nls_territory FALSE
nls_sort FALSE
nls_date_language FALSE
nls_date_format FALSE
nls_currency FALSE
NAME ISSYS_MOD
---------------------------------------------------------------- ---------
nls_numeric_characters FALSE
nls_iso_currency FALSE
nls_calendar FALSE
nls_time_format FALSE
nls_timestamp_format FALSE
nls_time_tz_format FALSE
nls_timestamp_tz_format FALSE
nls_dual_currency FALSE
nls_comp FALSE
nls_length_semantics IMMEDIATE
nls_nchar_conv_excp IMMEDIATE
NAME ISSYS_MOD
---------------------------------------------------------------- ---------
filesystemio_options IMMEDIATE
disk_asynch_io FALSE
tape_asynch_io FALSE
dbwr_io_slaves FALSE
backup_tape_io_slaves DEFERRED
resource_manager_plan IMMEDIATE
cluster_interconnects FALSE
file_mapping IMMEDIATE
active_instance_count FALSE
control_files FALSE
db_file_name_convert FALSE
NAME ISSYS_MOD
---------------------------------------------------------------- ---------
log_file_name_convert FALSE
db_block_buffers FALSE
db_block_checksum IMMEDIATE
db_block_size FALSE
db_writer_processes FALSE
db_keep_cache_size IMMEDIATE
db_recycle_cache_size IMMEDIATE
db_2k_cache_size IMMEDIATE
db_4k_cache_size IMMEDIATE
db_8k_cache_size IMMEDIATE
db_16k_cache_size IMMEDIATE
NAME ISSYS_MOD
---------------------------------------------------------------- ---------
db_32k_cache_size IMMEDIATE
db_cache_size IMMEDIATE
buffer_pool_keep FALSE
buffer_pool_recycle FALSE
db_cache_advice IMMEDIATE
max_commit_propagation_delay FALSE
compatible FALSE
remote_archive_enable FALSE
log_archive_start FALSE
log_archive_dest IMMEDIATE
log_archive_duplex_dest IMMEDIATE
NAME ISSYS_MOD
---------------------------------------------------------------- ---------
log_archive_dest_1 IMMEDIATE
log_archive_dest_2 IMMEDIATE
log_archive_dest_3 IMMEDIATE
log_archive_dest_4 IMMEDIATE
log_archive_dest_5 IMMEDIATE
log_archive_dest_6 IMMEDIATE
log_archive_dest_7 IMMEDIATE
log_archive_dest_8 IMMEDIATE
log_archive_dest_9 IMMEDIATE
log_archive_dest_10 IMMEDIATE
log_archive_dest_state_1 IMMEDIATE
NAME ISSYS_MOD
---------------------------------------------------------------- ---------
log_archive_dest_state_2 IMMEDIATE
log_archive_dest_state_3 IMMEDIATE
log_archive_dest_state_4 IMMEDIATE
log_archive_dest_state_5 IMMEDIATE
log_archive_dest_state_6 IMMEDIATE
log_archive_dest_state_7 IMMEDIATE
log_archive_dest_state_8 IMMEDIATE
log_archive_dest_state_9 IMMEDIATE
log_archive_dest_state_10 IMMEDIATE
log_archive_max_processes IMMEDIATE
log_archive_min_succeed_dest IMMEDIATE
NAME ISSYS_MOD
---------------------------------------------------------------- ---------
standby_archive_dest IMMEDIATE
log_archive_trace IMMEDIATE
fal_server IMMEDIATE
fal_client IMMEDIATE
log_archive_format FALSE
log_buffer FALSE
log_checkpoint_interval IMMEDIATE
log_checkpoint_timeout IMMEDIATE
archive_lag_target IMMEDIATE
log_parallelism FALSE
db_files FALSE
NAME ISSYS_MOD
---------------------------------------------------------------- ---------
db_file_multiblock_read_count IMMEDIATE
read_only_open_delayed FALSE
cluster_database FALSE
parallel_server FALSE
parallel_server_instances FALSE
cluster_database_instances FALSE
db_create_file_dest IMMEDIATE
db_create_online_log_dest_1 IMMEDIATE
db_create_online_log_dest_2 IMMEDIATE
db_create_online_log_dest_3 IMMEDIATE
db_create_online_log_dest_4 IMMEDIATE
NAME ISSYS_MOD
---------------------------------------------------------------- ---------
db_create_online_log_dest_5 IMMEDIATE
standby_file_management IMMEDIATE
gc_files_to_locks FALSE
thread FALSE
fast_start_io_target IMMEDIATE
fast_start_mttr_target IMMEDIATE
log_checkpoints_to_alert IMMEDIATE
recovery_parallelism FALSE
control_file_record_keep_time IMMEDIATE
logmnr_max_persistent_sessions FALSE
dml_locks FALSE
NAME ISSYS_MOD
---------------------------------------------------------------- ---------
row_locking FALSE
serializable FALSE
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