Hidden Parameters in Oracle AI Database 26ai H.17 Data Guard (33)

 

Name	Type	Value	At default?	Level	PDB	RAC inst.	Flags	Description
_adg_adt_redirect_apply_lag_threshold	Integer	12000	yes	SYSTEM imm.	N	Y		Maximum centi-seconds of apply lag threshold
_adg_adt_redirect_catchup_wait_time	Integer	12000	yes	SYSTEM imm.	N	Y		Maximum centi-seconds for standby to catch up
_adg_auto_close_pdb	Boolean	TRUE	yes	SYSTEM imm.	N	Y		ADG recovery auto close PDB upon PDB drop/unplug/rename marker
_adg_count_beyond_limit	Integer	0	yes	SYSTEM imm.	N	Y		Count the total number of objects if beyond redo marker length.
_adg_defer_segstat	Boolean	TRUE	yes	SYSTEM imm.	N	Y		Defer the segment statistics update on standby.
_adg_distributed_lockmaster	Boolean	FALSE	yes	STATIC	N	N		standby runs under ADG distributed lockmaster mode
_adg_influx_qscn_gap	Integer	0	yes	SYSTEM imm.	N	Y		maximum time gap between influx scn and qscn update in seconds
_adg_instance_recovery	Boolean	TRUE	yes	STATIC	N	N		enable ADG instance recovery
_adg_objectlock_attempts	Integer	2	yes	SYSTEM imm.	N	Y		Maximum attempts for objectlock get on ADG
_adg_objectlock_maxnum	Integer	1000	yes	SYSTEM imm.	N	Y		The maximum limit of the objectlock number on ADG
_adg_objectlock_timeout	Integer	0	yes	SYSTEM imm.	N	Y		timeout for objectlock get on ADG in centiseconds
_adg_parselock_holder_throttle_timeout	Integer	10	yes	SESSION	Y	Y		number of seconds ADG parse lock holders timeout on long waits
_adg_parselock_timeout	Integer	0	yes	SYSTEM imm.	N	Y		timeout for parselock get on ADG in centiseconds
_adg_parselock_timeout_sleep	Integer	100	yes	SYSTEM imm.	N	Y		sleep duration after a parselock timeout on ADG in milliseconds
_adg_redirect_upd_to_primary_max_retries	Integer	500	yes	SYSTEM imm.	N	Y		max retries for ADT redirect to Primary from ADG
_dg_broker_trace_level	String		yes	SYSTEM imm.	N	Y		data guard broker trace level
_dg_cf_check_timer	Integer	15	yes	SYSTEM imm.	N	Y		Data Guard controlfile check timer
_dg_corrupt_redo_log	Integer	0	yes	SYSTEM imm.	N	Y		Corrupt redo log validation during archivals
_dgb_dgpdb_appst	String		yes	SYSTEM imm.	N	N		DGPDBs with apply state off
_dgpdb_auto_task_defaults	String	enable_feature	yes	SYSTEM imm.	N	Y		options for DGPDB initialization
_dgpdb_cf_retention	Integer	10080	yes	SYSTEM imm.	N	Y		number of minutes to keep the control file copy made during role change to primary
_dgpdb_file_name_convert	String		yes	SYSTEM imm.	Y	Y		datafile name convert patterns and strings for per PDB standby
_dgpdb_pcf_cf_apply_time	Integer	600	yes	SYSTEM imm.	N	Y		DGPDB pcf to cf mark apply time in seconds
_dgpdb_pcf_cf_sync_time	Integer	43200	yes	SYSTEM imm.	N	Y		DGPDB pcf to cf sync time in seconds
_dgpdb_rc_notify_check_interval	Integer	5	yes	SYSTEM imm.	N	Y		number of minutes between attempts to send role change notifications to their prior primary site
_dgpdb_standby_controlfile_name	String	dgpdb_stdby_cf_pdbid_%u_%u_%u.cf	yes	STATIC	N	N		a name template with three %u's for DGPDB standby controlfile
_standby_auto_flashback	Boolean	TRUE	yes	SYSTEM imm.	N	Y		Standby automatic flashback when primary flashed back
_standby_causal_heartbeat_timeout	Integer	2	yes	STATIC	N	N		readable standby causal heartbeat timeout
_standby_flush_mode	String	SLFLUSH	yes	STATIC	N	N		standby flush mode
_standby_implicit_rcv_timeout	Integer	3	yes	SYSTEM imm.	N	Y		minutes to wait for redo during standby implicit recovery
_standby_newkey_keystore_location	String		yes	SYSTEM imm.	N	Y		Location of keystore on standby having new key
_standby_switchover_timeout	Integer	120	yes	SYSTEM imm.	N	Y		Number of secords for standby switchover enqueue timeout
_standby_temp_file_management	String	AUTO	yes	SYSTEM imm.	N	Y		tempfile management on standby databases

Hidden Parameters in Oracle AI Database 26ai H.16 Undo / flashback (57)

 

Name	Type	Value	At default?	Level	PDB	RAC inst.	Flags	Description
_flashback_11_1_block_new_opt	Boolean	FALSE	yes	STATIC	N	N		use 11.1 flashback block new optimization scheme
_flashback_allow_noarchivelog	Boolean	FALSE	yes	SYSTEM imm.	N	Y		Allow enabling flashback on noarchivelog database
_flashback_archiver_partition_size	Integer	0	yes	SYSTEM imm.	N	Y		flashback archiver table partition size
_flashback_barrier_interval	Integer	1800	yes	STATIC	N	N		Flashback barrier interval in seconds
_flashback_copy_latches	Integer	10	yes	STATIC	N	N		Number of flashback copy latches
_flashback_database_test_only	Boolean	FALSE	yes	SESSION	N	N		Run Flashback Database in test mode
_flashback_delete_chunk_MB	Integer	128	yes	SYSTEM imm.	N	Y		Amount of flashback log (in MB) to delete in one attempt
_flashback_dynamic_enable	Boolean	TRUE	yes	STATIC	N	N		enable flashback enable code path
_flashback_dynamic_enable_failure	Integer	0	yes	SYSTEM imm.	N	Y		Simulate failures during dynamic enable
_flashback_enable_ra	Boolean	TRUE	yes	STATIC	N	N		Flashback enable read ahead
_flashback_format_chunk_mb	Integer	4	yes	SYSTEM imm.	N	Y		Chunk mega-bytes for formatting flashback logs using sync write
_flashback_format_chunk_mb_dwrite	Integer	16	yes	SYSTEM imm.	N	Y		Chunk mega-bytes for formatting flashback logs using delayed write
_flashback_fuzzy_barrier	Boolean	TRUE	yes	SYSTEM imm.	N	Y		Use flashback fuzzy barrier
_flashback_generation_buffer_size	Big integer	16777216	yes	STATIC	N	N		flashback generation buffer size
_flashback_hint_barrier_percent	Integer	20	yes	STATIC	N	N		Flashback hint barrier percent
_flashback_log_io_error_behavior	Integer	0	yes	SYSTEM imm.	N	N		Specify Flashback log I/O error behavior
_flashback_log_min_size	Integer	100	yes	STATIC	N	N		Minimum flashback log size
_flashback_log_rac_balance_factor	Integer	10	yes	SYSTEM imm.	N	Y		flashback log rac balance factor
_flashback_log_size	Integer	1000	yes	STATIC	N	N		Flashback log size
_flashback_logfile_enqueue_timeout	Integer	600	yes	STATIC	N	N		flashback logfile enqueue timeout for opens
_flashback_marker_cache_enabled	Boolean	TRUE	yes	SYSTEM imm.	N	Y		Enable flashback database marker cache
_flashback_marker_cache_size	Integer	328	yes	STATIC	N	N		Size of flashback database marker cache
_flashback_marker_for_every_grp	Boolean	FALSE	yes	STATIC	N	N		generate a new flashback marker for every GRP
_flashback_max_log_size	Big integer	0	yes	SYSTEM imm.	N	N		Maximum flashback log size in bytes (OS limit)
_flashback_max_n_log_per_thread	Integer	2048	yes	STATIC	N	N		Maximum number of flashback logs per flashback thread
_flashback_max_standby_sync_span	Integer	300	yes	SYSTEM imm.	N	Y		Maximum time span between standby recovery sync for flashback
_flashback_n_log_per_thread	Integer	128	yes	STATIC	N	N		Desired number of flashback logs per flashback thread
_flashback_pdb_thread_filter_disable	Boolean	FALSE	yes	STATIC	N	N		disable per PDB thread filter optimization
_flashback_prepare_log	Boolean	TRUE	yes	SYSTEM imm.	N	Y		Prepare Flashback logs in the background
_flashback_reclaim_monitor_window	Integer	7	yes	SYSTEM imm.	N	Y		Proactive flashback logs reclaimation window
_flashback_reclaim_speed_up	Boolean	FALSE	yes	SYSTEM imm.	N	Y		Proactive flashback logs reclaimation speed up
_flashback_size_based_on_redo	Boolean	TRUE	yes	SYSTEM imm.	N	Y		Size new flashback logs based on average redo log size
_flashback_standby_barrier_interval	Integer	1	yes	STATIC	N	N		Flashback standby barrier interval in seconds
_flashback_standby_check_barrier_MIRA	Integer	20	yes	STATIC	N	N		Flashback standby check barrier generation in seconds
_flashback_standby_check_minpfh_MIRA	Integer	15	yes	STATIC	N	N		Flashback standby check minimum high fuzzy scn in seconds
_flashback_stby_support_mira	Boolean	TRUE	yes	STATIC	N	N		Flashback database on standby supports MIRA
_flashback_validate_controlfile	Boolean	FALSE	yes	SYSTEM imm.	N	Y		validate flashback pointers in controlfile for 11.2.0.2 database
_flashback_verbose_info	Boolean	FALSE	yes	SYSTEM imm.	N	Y		Print verbose information about flashback database
_flashback_write_max_loop_limit	Integer	10	yes	SYSTEM imm.	N	Y		Flashback writer loop limit before it returns
_rollback_segment_count	Integer	0	yes	SYSTEM imm.	Y	Y		number of undo segments
_rollback_segment_initial	Integer	1	yes	STATIC	Y	N		starting undo segment number
_rollback_stopat	Integer	0	yes	SYSTEM imm.	N	Y		stop at -position to step rollback
_smu_debug_mode	Big integer	0	yes	SYSTEM imm.	Y	Y		- set debug event for testing SMU operations
_smu_error_simulation_site	Integer	0	yes	SESSION	Y	N		site ID of error simulation in KTU code
_smu_error_simulation_type	Integer	0	yes	SESSION	Y	N		error type for error simulation in KTU code
_smu_timeouts	String		yes	SYSTEM imm.	Y	Y		comma-separated AND double-quoted list of AUM timeouts: mql, tur, sess_exprn, qry_exprn, slot_intvl
_undo_autotune	Boolean	TRUE	yes	SYSTEM imm.	Y	Y		enable auto tuning of undo_retention
_undo_block_compression	Boolean	TRUE	yes	SESSION	Y	Y		enable undo block compression
_undo_debug_mode	Integer	0	yes	SESSION	Y	Y		debug flag for undo related operations
_undo_debug_usage	Integer	0	yes	SYSTEM imm.	N	Y		invoke undo usage functions for testing
_undo_ofd_enabled	Boolean	TRUE	yes	SYSTEM imm.	Y	Y		enable ordered offline drop of undo segments for datafile shrink
_undo_ofd_excess	Integer	10	yes	SYSTEM imm.	Y	Y		percent of excess undo segments to offline or drop
_undo_ofd_reserve	Integer	30	yes	SYSTEM imm.	Y	Y		percent of excess undo segments to keep online
_undo_retention_time_limit	Integer	3600	yes	SYSTEM imm.	Y	Y		undo retention time limit in seconds
_undo_tbs_slave_percent	Integer	0	yes	SYSTEM imm.	N	Y		Percentage of redo slaves for undo tablespace
_undotbs_regular_tables	Boolean	FALSE	yes	SYSTEM imm.	N	Y		Create regular tables in undo tablespace
_undotbs_stepdown_pcent	Integer	75	yes	SYSTEM imm.	N	Y		Undo Tablespace small allocation step down percentage