前回に続き、Oracle Database19cと21cの隠しパラメータを比較した結果の纏め。今回は19cと比較して21cで新規に登場した隠しパラメータのうち、_o～_zから始まる隠しパラメータを記載する。
※19cとの比較による新規隠しパラメータの抽出であるため、20cで新規登場したものも21cでの新規として記載する。隠しパラメータ数が多いため、PCでの閲覧推奨。
5.新規隠しパラメータ(_o* ～ _z*)
新規の隠しパラメータは625個存在し、_o* ～ _z*な隠しパラメータは182個存在した。
| パラメータ名 | デフォルト値 | ALTER SESSION | ALTER SYSTEM | パラメータ概要 |
|---|---|---|---|---|
| _object_activity_control | 0 | TRUE | IMMEDIATE | controls tracing for object activity tracking system (OATS) |
| _object_activity_disable | 0 | TRUE | IMMEDIATE | disables some object activity tracking (OATS) |
| _object_activity_tracking | TRUE | TRUE | IMMEDIATE | enable object activity tracking system (OATS) |
| _obsolete_result_cache_mode | MANUAL | TRUE | IMMEDIATE | USERS SHOULD NOT SET THIS! Used for old qksced parameterof result_cache_mode |
| _ofs_read_buffer_size | 1031680 | FALSE | IMMEDIATE | OFS read ahead buffer size in bytes |
| _onl_ddl_progress | 3 | TRUE | IMMEDIATE | track progress of online ddl |
| _onl_pmo_wait_query | 0 | TRUE | IMMEDIATE | online pmos wait for queries after swapping partitions |
| _onl_pmo_wait_timeout | 0 | TRUE | IMMEDIATE | online pmos wait for queries after swapping partitions timeout |
| _online_pmo_global_index_method | CLEANUP ONLY | TRUE | IMMEDIATE | Unique global index method for partition maintenance DDLs |
| _optimize_dvconfig_cloudpdb | FALSE | FALSE | IMMEDIATE | Optimize Database Vault setup for cloud PDB |
| _optimizer_exists_to_any_rewrite | TRUE | TRUE | IMMEDIATE | consider exists-to-any rewrite of subqueries |
| _optimizer_nested_loop_join | on | TRUE | IMMEDIATE | favor/unfavor nested loop join |
| _optimizer_unnest_update_set_subq | on | TRUE | IMMEDIATE | enables unnesting of subquery in set for update |
| _optimizer_use_stats_models | FALSE | TRUE | IMMEDIATE | use optimizer statistics extrapolation models |
| _optimizer_wc_filter_pushdown | TRUE | TRUE | IMMEDIATE | enable/disable with clause filter predicate pushdown |
| _oracle_script_counter | 0 | TRUE | FALSE | Helper parameter to set the value of _oracle_script counter |
| _partial_log_preserve_space | TRUE | TRUE | IMMEDIATE | use only required space for partial archive logs |
| _path_prefix_create_dir | TRUE | TRUE | IMMEDIATE | Create path in file system for CREATE DIRECTORY with PATH_PREFIX |
| _pdb_char_set_intconv | FALSE | TRUE | IMMEDIATE | Enforce internal_convert for PDB character set conversion |
| _pdb_clone_preserve_guid | FALSE | TRUE | FALSE | Use same guid for a pdb clone |
| _pdb_create_use_sysoper_conn | FALSE | TRUE | IMMEDIATE | spread file copy slaves across instances |
| _pdb_datapatch_violation_restricted | TRUE | TRUE | IMMEDIATE | Open pdb in restricted mode for datapatch error violation |
| _pdb_file_copy_affinitize | FALSE | TRUE | IMMEDIATE | spread file copy slaves across instances |
| _pdb_file_copy_buffers | 8 | TRUE | IMMEDIATE | number of buffers to use for pdb file copy |
| _pdb_force_cfd | FALSE | FALSE | IMMEDIATE | Force DB_CREATE_FILE_DEST path for all datafiles in PDB |
| _pdb_hybrid_read_only | FALSE | TRUE | IMMEDIATE | Hybrid read only mode allows CDB common user to patch the PDB |
| _pdb_ktg_buffer_size | 16 | TRUE | IMMEDIATE | KTG buffer size (in KB) to store inmemory traces |
| _pdb_oper_trace_threshold | 600 | TRUE | IMMEDIATE | PDB operations timing trace threshold |
| _pdb_oper_trace_threshold_softassert | FALSE | TRUE | IMMEDIATE | PDB operations timing threshold soft assert |
| _pdb_read_only_refresh | FALSE | TRUE | IMMEDIATE | allow refresh when pdb is open r/o |
| _pdb_refresh_apply_master_key_rekey | TRUE | TRUE | IMMEDIATE | Apply master rekey marker during pdb refresh |
| _pdb_refresh_use_dblink_to_catalog | FALSE | TRUE | IMMEDIATE | Use central catalog for pdb refresh |
| _pdb_refresh_use_local_logs | TRUE | TRUE | IMMEDIATE | Use local logs for pdb refresh |
| _pdb_small_table_threshold | FALSE | FALSE | lower threshold level of table size for direct reads in a pdb | |
| _pdb_transition_clean_bg_delay | 0 | FALSE | IMMEDIATE | delay in GEN0 to transition PDB to clean state |
| _pmem_exchange_cold_victim_threshold | 0 | FALSE | IMMEDIATE | worthy touch count threshold for a victim buffer to be exchanged into pmem |
| _pmem_small_table_threshold | 20 | TRUE | DEFERRED | lower threshold of PMEM table size as percentage to PMEM cache for direct reads |
| _pmemfs_alloc_dataptrs | 1 | TRUE | IMMEDIATE | Set PMEMfs to preallocate inode tree |
| _pmemfs_enable_spacetracking | FALSE | TRUE | IMMEDIATE | Enable PMEMfs Space Accounting Checks |
| _pmemfs_shrink_level | 0 | FALSE | IMMEDIATE | Enable pmemstore shrink |
| _pmemfs_smallfile_threshold | 1024 | FALSE | IMMEDIATE | Block count threshold for metedata |
| _post_run_job_evaluation | FALSE | FALSE | IMMEDIATE | Control if jobs should evaluate at end of execution |
| _pqq_pdb_load_publish_threshold | 0 | FALSE | IMMEDIATE | difference in percentage controlling PDB load publish |
| _process_max_pred_increase | 20000 | FALSE | IMMEDIATE | process SO max predicted increase |
| _process_percent_rampup_end | 10000 | FALSE | FALSE | process SO percent rampup end |
| _process_percent_rampup_start | 1000 | FALSE | FALSE | process SO percent rampup start |
| _process_prediction_failover_buffer | 1 | FALSE | IMMEDIATE | process prediction failover buffer |
| _process_save_prediction | FALSE | FALSE | IMMEDIATE | save process prediction for next instance startup |
| _process_so_max_inc | 20000 | FALSE | IMMEDIATE | process SO max inc |
| _profile_sensitive_users | FALSE | IMMEDIATE | Database Users with restricted password profile | |
| _psdclog_enable | FALSE | TRUE | IMMEDIATE | Mandatory Cloud Logging of PL/SQL Utility Packages Usages |
| _psdclog_threshold | 10 | TRUE | IMMEDIATE | Threshold for Cloud Logging of PL/SQL Utility Packages Usages |
| _psr_opt | enable feature | FALSE | IMMEDIATE | options for standby pdb recovery |
| _px_adaptive_dist_nij_enabled | on | TRUE | IMMEDIATE | enable adaptive distribution methods for left non-inner joins |
| _px_extended_join_skew_handling | TRUE | TRUE | IMMEDIATE | enables extended skew handling for parallel joins |
| _px_oneslave_per_instance_parse | TRUE | TRUE | IMMEDIATE | send parse to one slave per instance |
| _px_parallelize_non_native_datatype | TRUE | TRUE | IMMEDIATE | enable parallelization for non-native datatypes |
| _remote_http_port | 0 | FALSE | IMMEDIATE | HTTP port number registered with remote listener |
| _reset_increase_lmd_process | TRUE | FALSE | IMMEDIATE | set to true to allow reset of _increase_lmd_process changes |
| _reset_increase_lms_process | TRUE | FALSE | IMMEDIATE | set to true to allow reset of _increase_lms_process changes |
| _result_cache_do_recycle_period | 300 | FALSE | IMMEDIATE | Timeout value for DOs added through invalidation |
| _result_cache_global_send | TRUE | FALSE | IMMEDIATE | Is global send conditional in RAC? |
| _result_cache_history_size | 0 | FALSE | IMMEDIATE | memory used to track PL/SQL function history |
| _result_cache_latch_count | 0 | FALSE | FALSE | number of result cache latches |
| _result_cache_load_rate | 1 | FALSE | IMMEDIATE | Simulated global load rate (bytes per 1/100 sec) |
| _result_cache_object_black_list | 0 | FALSE | IMMEDIATE | object numbers not allowed to use the result cache |
| _result_cache_use_hash_table | TRUE | FALSE | IMMEDIATE | whether to use hash table for object tracking |
| _rollback_segment_count | 0 | FALSE | IMMEDIATE | number of undo segments |
| _root_clone_skip_trigger | TRUE | TRUE | IMMEDIATE | Skip trigger in Application Root Clone |
| _rsrc_cpu_count | 0 | FALSE | IMMEDIATE | CPU Count for allocating resources. |
| _runtime_index_key_length_check | 0 | TRUE | FALSE | allow runtime checking of index key length |
| _runtime_limit_parallel_fptr | 60 | FALSE | IMMEDIATE | run-time limit for for parallel first-pass recovery |
| _second_spare_pdb_parameter | TRUE | IMMEDIATE | second spare pdb parameter - integer | |
| _securefile_shrink_enable_nowaitlck | FALSE | TRUE | IMMEDIATE | Enable Securefile Shrink NOWAIT row locking |
| _securefile_shrink_hash_table_limit | 100 | FALSE | IMMEDIATE | Size limit on Securefile Lob Shrink state Hash table |
| _securefiles_dealloc_cfs | 0 | FALSE | FALSE | securefiles deallocate directly to CFS |
| _sess_sign_num_pools | 16 | FALSE | FALSE | session signature: number of pools |
| _sess_template_all_overflow | FALSE | TRUE | IMMEDIATE | session template: put all attributes into overflow |
| _sess_template_cache_buckets | 128 | FALSE | FALSE | session template: number of cache buckets |
| _sess_template_enabled | TRUE | TRUE | IMMEDIATE | session template: enabled |
| _sess_template_max_cache_size | 5 | FALSE | IMMEDIATE | session template: max cache size (in 1/100% of SGA) |
| _sess_template_new_lists | 16 | FALSE | FALSE | session template: number of new lists |
| _sess_template_purge_time_mins | 60 | FALSE | IMMEDIATE | session template: purge time (in minutes) |
| _sess_template_spares | TRUE | FALSE | FALSE | session template: spares |
| _session_limit_percent_cap | 25 | FALSE | IMMEDIATE | session limit percent cap |
| _session_modp_list | 2 | FALSE | IMMEDIATE | send session's modified parameter list to client |
| _session_so_max_inc | 20000 | FALSE | IMMEDIATE | session SO max inc |
| _seventeenth_spare_pdb_parameter | TRUE | IMMEDIATE | seventeenth spare pdb parameter - integer | |
| _seventh_spare_pdb_parameter | TRUE | IMMEDIATE | seventh spare pdb parameter - integer | |
| _seventieth_spare_pdb_parameter | TRUE | TRUE | IMMEDIATE | seventieth spare pdb parameter - boolean |
| _shard_ddl_policy | ASYNC | TRUE | IMMEDIATE | DDL execution mode for shards |
| _shard_sesscache_cnt | 0 | FALSE | IMMEDIATE | enable session caching for shard SQL |
| _singleton_service_goodness_disabled | TRUE | FALSE | IMMEDIATE | singleton srvc goodness |
| _sixteenth_spare_pdb_parameter | TRUE | IMMEDIATE | sixteenth spare pdb parameter - integer | |
| _sixth_spare_pdb_parameter | TRUE | IMMEDIATE | sixth spare pdb parameter - integer | |
| _sixtieth_spare_pdb_parameter | TRUE | TRUE | IMMEDIATE | sixtieth spare pdb parameter - boolean |
| _sixty-eighth_spare_pdb_parameter | TRUE | TRUE | IMMEDIATE | sixty-eighth spare pdb parameter - boolean |
| _sixty-fifth_spare_pdb_parameter | TRUE | TRUE | IMMEDIATE | sixty-fifth spare pdb parameter - boolean |
| _sixty-first_spare_pdb_parameter | TRUE | TRUE | IMMEDIATE | sixty-first spare pdb parameter - boolean |
| _sixty-fourth_spare_pdb_parameter | TRUE | TRUE | IMMEDIATE | sixty-fourth spare pdb parameter - boolean |
| _sixty-ninth_spare_pdb_parameter | TRUE | TRUE | IMMEDIATE | sixty-ninth spare pdb parameter - boolean |
| _sixty-second_spare_pdb_parameter | TRUE | TRUE | IMMEDIATE | sixty-second spare pdb parameter - boolean |
| _sixty-seventh_spare_pdb_parameter | TRUE | TRUE | IMMEDIATE | sixty-seventh spare pdb parameter - boolean |
| _sixty-sixth_spare_pdb_parameter | TRUE | TRUE | IMMEDIATE | sixty-sixth spare pdb parameter - boolean |
| _sixty-third_spare_pdb_parameter | TRUE | TRUE | IMMEDIATE | sixty-third spare pdb parameter - boolean |
| _skip_oradism_check | FALSE | FALSE | FALSE | Switch on all features for the purpose of testing |
| _skip_sequence_cache_close_immediate | FALSE | TRUE | IMMEDIATE | Skip sequence cache flush on pdb shutdown immediate |
| _smon_ofd_sleep_interval | 300 | FALSE | IMMEDIATE | smon sleep internval for undo ofd test |
| _spec_replace_locks_body | TRUE | TRUE | IMMEDIATE | Lock body when replacing a package specification |
| _sqlexec_aggregation_settings | 0 | TRUE | IMMEDIATE | runtime settings for aggregation |
| _sqlexec_hash_aggr_small_mem_blocks | 2 | TRUE | IMMEDIATE | hash aggregation small initial memory footprint number of blocks |
| _sqlexec_hash_based_distagg_ser_civ_enabled | TRUE | TRUE | IMMEDIATE | enable hash based distinct aggregation in serial/CIV queries |
| _sqlexec_hash_based_set_operation_enabled | TRUE | TRUE | IMMEDIATE | enable/disable hash based set operation |
| _sqlexec_hash_rollup_enabled | TRUE | TRUE | IMMEDIATE | enable hash rollup |
| _sqlexec_use_delayed_unpacking | TRUE | TRUE | IMMEDIATE | enable/disable the usage of delayed unpacking |
| _STFForceTranslateOracleSQL | FALSE | FALSE | IMMEDIATE | if TRUE translation profile will translate Oracle SQL statements |
| _strict_utl_http_smtp | TRUE | TRUE | IMMEDIATE | Enforce strict URL checks on UTL_HTTP and UTL_SMTP Packages |
| _subquery_pruning_flags | 0 | TRUE | IMMEDIATE | subquery pruning flags |
| _swat_ver_mv_knob | 0 | TRUE | FALSE | Knob to control MV/REWRITE behavior |
| _symbol_no_translation | FALSE | TRUE | IMMEDIATE | disable symbol tranlations in call stacks |
| _sync_error_handler | TRUE | IMMEDIATE | error handler function for Application Sync | |
| _synchronous_rewrap_rac_ts_keys | FALSE | FALSE | IMMEDIATE | if TRUE, synchronously rewrap TS keys in all nodes in MK rekey |
| _system_memory_simulate | FALSE | FALSE | FALSE | system memory simulation mode, TRUE for hugetlbfs simulation |
| _tcpinfo_statistics_save_atexit | FALSE | TRUE | IMMEDIATE | TCP Info Statistics Save At Exit |
| _temp_undo_disable_refresh_clone | TRUE | TRUE | IMMEDIATE | is temp undo disabled on refreshable clone PDB |
| _tenth_spare_pdb_parameter | TRUE | IMMEDIATE | tenth spare pdb parameter - integer | |
| _test_flashback_shrink | 0 | FALSE | IMMEDIATE | test flashback datafile shrink feature |
| _test_flashback_shrink | 0 | FALSE | IMMEDIATE | test flashback datafile shrink feature |
| _test_param_13 | FALSE | TRUE | IMMEDIATE | test parmeter 13 - boolean |
| _test_param_14 | NONE | TRUE | IMMEDIATE | test parmeter 14 - string list |
| _test_param_15 | 50 | TRUE | IMMEDIATE | test parmeter 15 - integer |
| _test_param_4_1 | NONE | TRUE | FALSE | test parameter 4_1 - nonsys mod. string list |
| _test_param_pdb_spare | TRUE | IMMEDIATE | test parameter pdb spare | |
| _test_param_spare | TRUE | IMMEDIATE | test parameter spare | |
| _third_spare_pdb_parameter | TRUE | IMMEDIATE | third spare pdb parameter - integer | |
| _thirteenth_spare_pdb_parameter | TRUE | IMMEDIATE | thirteenth spare pdb parameter - integer | |
| _thirtieth_spare_pdb_parameter | TRUE | IMMEDIATE | thirtieth spare pdb parameter - string | |
| _thirty-eighth_spare_pdb_parameter | TRUE | IMMEDIATE | thirty-eighth spare pdb parameter - string | |
| _thirty-fifth_spare_pdb_parameter | TRUE | IMMEDIATE | thirty-fifth spare pdb parameter - string | |
| _thirty-first_spare_pdb_parameter | TRUE | IMMEDIATE | thirty-first spare pdb parameter - string | |
| _thirty-fourth_spare_pdb_parameter | TRUE | IMMEDIATE | thirty-fourth spare pdb parameter - string | |
| _thirty-ninth_spare_pdb_parameter | TRUE | IMMEDIATE | thirty-ninth spare pdb parameter - string | |
| _thirty-second_spare_pdb_parameter | TRUE | IMMEDIATE | thirty-second spare pdb parameter - string | |
| _thirty-seventh_spare_pdb_parameter | TRUE | IMMEDIATE | thirty-seventh spare pdb parameter - string | |
| _thirty-sixth_spare_pdb_parameter | TRUE | IMMEDIATE | thirty-sixth spare pdb parameter - string | |
| _thirty-third_spare_pdb_parameter | TRUE | IMMEDIATE | thirty-third spare pdb parameter - string | |
| _trace_suppress | TRUE | IMMEDIATE | suppresses matching trace for a given substring(prefix) | |
| _trace_suppress_disable | FALSE | FALSE | FALSE | Disable trace suppress feature |
| _ttc_annotations_level | 0 | FALSE | IMMEDIATE | enable ttc annotations |
| _twelfth_spare_pdb_parameter | TRUE | IMMEDIATE | twelfth spare pdb parameter - integer | |
| _twentieth_spare_pdb_parameter | TRUE | IMMEDIATE | twentieth spare pdb parameter - integer | |
| _twenty-eighth_spare_pdb_parameter | TRUE | IMMEDIATE | twenty-eighth spare pdb parameter - string | |
| _twenty-fifth_spare_pdb_parameter | TRUE | IMMEDIATE | twenty-fifth spare pdb parameter - string | |
| _twenty-first_spare_pdb_parameter | TRUE | IMMEDIATE | twenty-first spare pdb parameter - string | |
| _twenty-fourth_spare_pdb_parameter | TRUE | IMMEDIATE | twenty-fourth spare pdb parameter - string | |
| _twenty-ninth_spare_pdb_parameter | TRUE | IMMEDIATE | twenty-ninth spare pdb parameter - string | |
| _twenty-second_spare_pdb_parameter | TRUE | IMMEDIATE | twenty-second spare pdb parameter - string | |
| _twenty-seventh_spare_pdb_parameter | TRUE | IMMEDIATE | twenty-seventh spare pdb parameter - string | |
| _twenty-sixth_spare_pdb_parameter | TRUE | IMMEDIATE | twenty-sixth spare pdb parameter - string | |
| _twenty-third_spare_pdb_parameter | TRUE | IMMEDIATE | twenty-third spare pdb parameter - string | |
| _txn_spare1 | 0 | TRUE | IMMEDIATE | transaction spare variable1 |
| _txn_spare2 | 0 | TRUE | IMMEDIATE | transaction spare variable2 |
| _txn_spare3 | 0 | TRUE | IMMEDIATE | transaction spare variable3 |
| _undo_ofd_enabled | TRUE | FALSE | IMMEDIATE | enable ordered offline drop of undo segments for datafile shrink |
| _undo_ofd_excess | 10 | FALSE | IMMEDIATE | percent of excess undo segments to offline or drop |
| _undo_ofd_reserve | 30 | FALSE | IMMEDIATE | percent of excess undo segments to keep online |
| _unified_pga_block_size | 262144 | FALSE | FALSE | Unified PGA internal block size |
| _unified_pga_gran_free_timeout | 3000 | FALSE | IMMEDIATE | Granule free timeout |
| _unified_pga_gran_leak_timeout | 180000 | FALSE | IMMEDIATE | Granule leak timeout |
| _unified_pga_list_count | 16 | FALSE | FALSE | Unified PGA internal list count |
| _unified_pga_max_pool_size | 0 | FALSE | IMMEDIATE | max size in bytes of the unified pga pool |
| _upgrade_pdb_on_open | TRUE | TRUE | IMMEDIATE | Enable upgrading a PDB automatically on open |
| _ut_fast_lrg_prediction | FALSE | FALSE | FALSE | use short interval for session SO prediction |
| _utlfile_dirpath | FALSE | FALSE | FALSE | return Utl_File Accessible |
| _uts_disable_client_ip_trace | FALSE | FALSE | IMMEDIATE | Disables the printing of client IP address in trace files |
| _uts_force_seclabel_prefix | FALSE | FALSE | FALSE | Force output of trace record security label prefix |
| _verify_undo_quota | FALSE | TRUE | IMMEDIATE | TRUE - verify consistency of undo quota statistics |
| _write_renamed_datafile_name | FALSE | TRUE | IMMEDIATE | print renamed datafile names to alert log |
| _xs_sidp_allow_sha1 | TRUE | FALSE | IMMEDIATE | XS SIDP allow use of SHA1 |
| _zonemap_auto_candidate_table_min_size | 5000 | FALSE | IMMEDIATE | Minimum size for a table to be candidate for an automatic zonemap |
| _zonemap_auto_clustering_ratio | 50 | FALSE | IMMEDIATE | Data clustering ratio in percent for automatic zonemap columns |
| _zonemap_refresh_within_load | TRUE | TRUE | IMMEDIATE | Control the refresh of basic zonemaps during/after data load |
最後に。隠しパラメータの変更した場合、製品サポートを受けられなくなる可能性があるため、実際に変更する際は、Oracle Databaseのサポート契約先に問合せした後に実施することをお勧めする。
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