Oracle Database 21c Initialization Parameter, Hidden Parameter introduced, deprecated and obsolete.

Objective:

The objective of this blog is to share the information about the new database parameter and hidden parameter introduced in 21c along with the deprecated and obsolete database parameter.

The parameters are the backbone of the database that is responsible for running the database with full utilized I/O operations. The database parameters can be modified in the system or session level. Some of the parameters can be altered in memory level and do not require any database restart, and some are not which requires a database to restart to get reflect for the database instance. 

Oracle Database Parameters are the predefined values set for various memory segments and information on different location of files and log files for bringing up the database instance. Deprecated parameter means the parameter that is being replaced by a better alternative and shouldn’t be used, and obsolete parameter means the parameters are removed from the database and no longer in use. 

The Oracle Database Hidden parameter must not be changed without taking concern from Oracle support, changing the hidden parameter value may result in higher performance degradation and also serious corruption issue. Please go through the Metalink Doc ID 315631.1 for more information.

Note: The database parameter mentioned here are compared with respect to the previous production release database version 19c.

Now let’s begin to have the information on Oracle Database Version 21c parameters.

 

New Parameter introduced in Version 21c in comparison to 19c .

NAME	ISDEP	DESCRIPTION
_gc_policy_time	FALSE	how often to make object policy decisions in minutes
_gc_undo_affinity	FALSE	if TRUE, enable undo affinity
allow_deprecated_rpcs	FALSE	allow deprecated rpcs
auto_start_pdb_services	FALSE	Automatically start all PDB services on PDB Open
blockchain_table_max_no_drop	FALSE	maximum idle retention minutes for blockchain tables
container_data	FALSE	which containers should data be returned from?
dbnest_enable	FALSE	database Nest enable
dbnest_pdb_fs_conf	FALSE	PDB Filesystem configuration
diagnostics_control	FALSE	controls response when 'enabling diagnostics' privilege is absent
drcp_connection_limit	FALSE	DRCP connection limit
drcp_dedicated_opt	FALSE	Turn on/off dedicated optimization for DRCP
enable_per_pdb_drcp	FALSE	Turn on/off per PDB DRCP
heartbeat_batch_size	FALSE	Number of heartbeats to be sent in a batch
ignore_session_set_param_errors	FALSE	Ignore errors during alter session param set
inmemory_deep_vectorization	FALSE	In-Memory Deep Vectorization Enabled
kafka_config_file	FALSE	KSR pub/sub external message bus(KSRPS) CONFIGuration file
mandatory_user_profile	FALSE	Enforce Mandatory Password Profile for multitenant database
max_auth_servers	FALSE	Maximum size of auth pool
min_auth_servers	FALSE	Minimum size of auth pool
native_blockchain_features	FALSE	Native block chain enable/disable
optimizer_capture_sql_quarantine	FALSE	enable automatic creation/update of sql quarantine configuration
optimizer_cross_shard_resiliency	FALSE	enables resilient execution of cross shard queries
optimizer_real_time_statistics	FALSE	optimizer real time statistics on conventional DML
optimizer_session_type	FALSE	Controls Auto Index
optimizer_use_sql_quarantine	FALSE	enable use of sql quarantine
pkcs11_library_location	FALSE	PKCS#11 library location for Transparent Data Encryption
pmem_filestore	FALSE	Persistent Memory Filestore list
resource_manager_cpu_scope	FALSE	scope of CPU resource management
result_cache_execution_threshold	FALSE	minimum executions before a PL/SQL function is cached
result_cache_max_temp_result	FALSE	maximum temp per result as percent of total temp for result cache
result_cache_max_temp_size	FALSE	maximum amount of temp space to be used
shard_queries_restricted_by_key	FALSE	add shard key predicates to the query
tablespace_encryption_default_algorithm	FALSE	default tablespace encryption block cipher mode
tde_key_cache	FALSE	Enable caching of TDE intermediate key
timezone_version_upgrade_online	FALSE	enable/disable time zone version upgrade online

 

New Hidden parameter introduced in Version 21c in comparison to 19c.

PARAMETER	PARAMETER_DESCRIPTION
_STFForceTranslateOracleSQL	if TRUE translation profile will translate Oracle SQL statements
__db_pmem_direct_map_size_metadata	Size of PMEM memory metadata of DEFAULT buffer pool for standard block size buffers
__sess_template_test_attrs	session template: include test attributes
_adaptive_scalable_log_writer_evaluation_fraction	Serial/parallel log writer evaluation fraction (in 10000ths)
_adaptive_scalable_log_writer_evaluation_interval	Serial/parallel log writer evaluation interval (in seconds)
_age_block_batch_timeout_ms	timeout before shipping out the batched age blockmessages in milliseconds
_alert_segment_size	Alert-log segment size in MBs (1024*1024)
_alert_segment_textfile	Alert-log text-file also to be segmented
_alert_segments_max	Alert-log max segments to retain, 0 for unlimited
_allow_cross_version_chunk_move	Oracle internal parameter
_allow_fallback_to_dbkey	if TRUE, allow fallback to dbkey
_allow_privileged_session_dblink_conn	Allow privileged session for dblink connection
_allow_triggers_on_vpd_table	Allow triggers on VPD protected table in DML
_allow_xdb_anonymous_logon	Allow XDB anonymous logon
_allowed_pvf_owners	List of schemas allowed to own password verification function
_aq_queue_global_service	AQ queue global service
_aq_tm_processes_dump_interval	Time(minutes) between consecutive Dumps in alert log
_aqsharded_cached_hint	sharded queue cached hint
_aqsharded_enq_fresh_ptn_reload	start enqueueing to a fresh partition on reload
_aqsharded_lowmem_timeout	sharded queue low mem timeout (in centiseconds)
_aqsharded_reload_tune	sharded queue tune reload behaviour
_asm_allow_appliance_offlineonline	Allow OFFLINE/ONLINE DISK/FAILUREGROUP on ASM Appliances
_asm_buffer_overlap_tracer	Enables kfioBufOverlapTracer
_asm_diskgroup_renew_timeout	timeout FENC will give former ASMB group owner to renew
_asm_dump_split_pw	Seconds to wait before requesting dump of split pending writes
_asm_enable_map_share	Enable ASM extent map share
_asm_enable_vfreloc_on_rm	Enable voting file relocation on rolling migration
_asm_frag_threshold	Percentage threshold before disk/diskgroup is deemed fragmented
_asm_hard_check	H.A.R.D. check buffer before write operation
_asm_iosfailover_freq	Frequency limit after which db gives up on failing over to IOS
_asm_iosfailover_timeout	Time window within which db tries to failover to IOS
_asm_max_kfsg_free_heap_perc	Max percentage of SGA memory reserved for kfsga free heap
_asm_max_kfsg_free_heap_size	Max buffer size reserved for kfsga free heap
_asm_max_occupied	Maximum percentage of disk occupied to check for fragmentation
_asm_min_occupied	Minimum percentage of disk occupied to check for fragmentation
_asm_node_number	ASM node number
_asm_offline_wait_timeout	Timeout for offline wait
_asm_ownerid_trace_timeout	ownerid tracing threshold in seconds
_asm_pst_rsinfo	file redundancies to consider during PST liveness checks
_asm_scrub_max_cod_wait	Number of minutes to delay scrub COD recovery
_asm_shared_pool_latch_timeout	seconds before terminating inst if ASMB is waiting for shared pool latch during shutdown
_asm_showpdb_asmtbl	Allow asm table values to be shown in pdb
_asm_write_cancel_timeout_percentage	Percentage of the write timeout to wait before optional offline
_asm_xrov_cachelgio	ADVM cache large IO
_assert_single_current_buffer	if TRUE, check and assert only one current buffer
_assm_auto_tracing_threshold	ASSM threshold to start space search tracing
_auto_mv_enabled	enable/disable Auto MV logic in the sql access advisor
_autoptn_costing	DBMS_AUTO_PARTITION is compiling query for cost estimates
_autoptn_flags	DBMS_AUTO_PARTITION flags
_autoptn_translate_table_name	DBMS_AUTO_PARTITION table name translation
_autoptn_workload_id	DBMS_AUTO_PARTITION workload id
_autosts_capture_control	internal controls for auto STS capture
_autosts_long_interval	Auto STS long flush interval
_autosts_retention_interval	Auto STS retention interval
_autosts_short_interval	Auto STS short flush interval
_aux_storage_size	Auxillary storage for PDB.
_awr_data_masking	Enable/Disable AWR data masking functionality
_backup_interrupt_wait_time	specifies interrupt wait time in centi seconds
_bct_public_dba_buffer_dynresize_delay	control frequency of dynamic resizing of public dba buffers
_bigdata_offload_flag	BigDataSQL offload flag
_block_change_tracking_file	file location for broker to reenable BCT
_blockchainHeapSize	Set the heap size in bytes for blockchain
_blockchainTracing	Set tracing for blockchain
_blockchain_forced_off	force off blockchain
_blockchain_txn_apis_enabled	If true, the txn layer blockchain API'S kick in
_blockchain_txn_test_lvl	blockchain txn test lvl
_boc_mode	Broadcast-on-commit mode
_boc_rdma_wait_time	BOC RDMA busy wait time (microseconds)
_buffer_requests_to_drain	Buffer for requests to drain before planned failover
_bypass_sensitive_context	bypass sensitive handling for specific SYS_CONTEXT() parameters
_cdb_init_batch_size	Batch size for reading pdb info during CDB mount
_cdb_svlt_use_tcps	Use TCPS for CDB Servlet
_cell_metadata_compression	Cell metadata compression strategy
_cell_offload_vector_groupby_external	enable cell offload of vector group by with external tables
_cgs_clscevents_dumpinterval	cgs clsce events statistics dump interval in seconds
_cgs_publish_netinfo_collect_event_chmjf	enable cgs publish collect_netinfo event to event stream for CHM with CHM'S JASON format
_cgs_publish_netinfo_collect_event_chmjf_batchsz	batch size of cgs events publishing to CHM in json format via clsce event stream
_cgs_query_net_interface	api to query network interface
_cloud_mandatory_profile_setup	Mandatory Profile Setup for Multitenant Cloud Environment
_cluster_database_instances	number of instances to use for sizing cluster db SGA structures
_connect_string_settings_after_logon_triggers	set connect string session settings after logon triggers
_connect_string_settings_unalterable	make connect string session settings unalterable
_connstr_test_param	connect string workload behavior spare param
_consensus_follower_election_timeout	consensus follower's election timeout
_consensus_leader_heartbeat_interval	consensus leader's heartbeat interval
_consensus_leader_maximum_heartbeats	consensus leader's maximum heartbeats
_consensus_queue_maximum_elements	consensus queue maximum elements
_consensus_slaves_maximum_count	consensus slaves maximum count
_cp_del_free_sess	connection pool: delete free sessions when at PDB limit
_cp_del_free_sess_limit_secs	connection pool: delete free sessions time limit (in seconds)
_cputime_limit_parallel_fptr	CPU-time limit for for parallel first-pass recovery
_create_pdb_disable_mirror_reads	Disable mirror reads during create pdb
_create_pdb_flashback_barrier	force flashback barrier for create pdb
_cross_con_remove_pushed_preds	remove pushed predicates from query fetching across containers
_ctas_numfrags_hint	Hint for number of partition fragments to be loaded in a CTAS
_ctex_fk_copy_mode	Create table for exchange Copy mode for referential constraints
_datapump_bypass_tstz_check	Bypass Data Pump TSTZ version checking during import.
_datapump_hide_cdb_warning	Hide Data Pump warning for CDB$ROOT and PDB$SEED
_db_cache_advice_size_submultiple	cache advisory size submultiple
_db_cache_pmem_confidence_try	DB Cache PMEM buffer promote attempts for greater confidence
_db_cache_pmem_promotion_touch_rate_reset_interval	DB Cache PMEM promotion touch rate reset interval in sec
_db_cache_pmem_promotion_touch_rate_threshold_time	DB Cache PMEM promotion touch rate threshold time in sec
_db_cache_pmem_touch_rate_compare_per	DB Cache PMEM buffer touch rate additive percentage when comparingagainst dram touch rate
_db_cache_pmemp_len	DB Cache PMEM promotion list max length
_db_cache_xmem_promotion_algo_chosen	DB Cache Xmem/Pmem promotion algo
_db_nvm_promotion_deferred_tchcnt	touch count threshold which allows deferred background based nvm buffer promotion
_db_pmem_auto_resize_interval	PMEM auto resize interval in minutes
_db_pmem_direct_map_size	Size of direct mappable PMEM buffer cache
_db_replay_security_config	Database Replay Security Configuration
_dbnest_resource_opts	dbNest - resource options
_dbnest_skip_fed_root	Fed root is skipped so CDB nest is root of all pdbs
_dbopen_breakpoint	ALTER DATABASE OPEN codepath breakpoint
_dbreplay_mpk_key	Database Replay Package Key
_ddlapply_enable	DDL VIA APPLY Enable
_default_ini_trans_index	Default value of INI_TRANS enforced by DWCS lockdown for indexes
_default_ini_trans_table	Default value of INI_TRANS enforced by DWCS lockdown for tables
_default_oracle_fs_type	default file system type for an oracle file system
_default_service	Run default service
_defer_rcv_pdb_attach	Defer PDB domain attach in instance recovery
_defer_rewrap_controlfile_key_history	if TRUE, defer rewrap control file TS keys under next PDB open
_dgb_dgpdb_appst	DGPDBs with apply state off
_dgpdb_file_name_convert	datafile name convert patterns and strings for per PDB standby
_dgpdb_standby_controlfile_name	a name template with three %u's for DGPDB standby controlfile
_direct_io_via_mapped_pmem	if TRUE, direct path I/O will attempt to memory map files on PMEM
_disable_block_corruption_track	disable block corruption tracking
_disable_foreign_scn_adjust	Disable foreign SCN adjustment
_disable_ilm_internal	Force disable internal ilm stats and drop ilm segment
_disable_mandatory_profile_onclone	Disable Mandatory Profile check on clone of a PDB
_disable_marking_noops	Don't mark any captured statements as no-ops.
_disable_orphan_pdb_recovery	Disable PDB PITR/FB to orphan PDB incarnation
_disable_pdb_space_check	Disable pdb storage usage check in the session
_disable_sga_filedel	disable deletion of files used for SGA
_dmm_ser_test	Stress testing for serialized models
_dmm_xgboost_max_memory	xgboost maximum memory
_dp_force_length_semantics	Force nls length semantics
_dynamic_hash_bucket_array	dynamic hash bucket array
_dynamic_processes_force_timeout	dynamic process force timeout
_dynamic_processes_max_oom_timeout	dynamic process max timeout for out of memory
_dynamic_processes_wait_timeout	dynamic process wait timeout for new process
_eighteenth_spare_pdb_parameter	eighteenth spare pdb parameter - integer
_eighth_spare_pdb_parameter	eighth spare pdb parameter - integer
_eighty-second_spare_parameter	eighty-second spare parameter - string
_eleventh_spare_pdb_parameter	eleventh spare pdb parameter - integer
_enable_bug_29838374	enable/disable bug fix 29838374
_enable_cdb_all_sync	Is CDB-wide ALL sync enabled
_enable_dbwr_parallel_invalidations	if TRUE, enables flush and invalidate by DBWRs
_enable_dynamic_processes	dynamic process SOs
_enable_fsdirect_odmlib	enable or disable FsDirect static ODM library
_enable_fsdirect_pin	enable direct pin of FsDirect blocks
_enable_fsdirect_rac	enable FsDirect in RAC
_enable_gsm_listener_networks	gsm listener in listener networks
_enable_ignorable_error_capture	Capture statement if error is ignorable
_enable_increase_lms_process	set to true to allow _increase_lms_process changes
_enable_load_from_clone	Is load from a Root Clone allowed
_enable_log_memory_protection_key	enable memory protection keys (log)
_enable_memory_protection_keys	Enable memory protection keys usage
_enable_mle	enable MLE
_enable_pdb_skiplist_recovery	Enable pdb skip list setup during media recovery.
_enable_pdb_skiplist_redogen	Enable pdb skip list setup during redo generation.
_enable_per_container_acl	Enable Per Container ACL
_enable_pmem_direct_cache	if TRUE, enable PMEM direct mapped buffers
_enable_pmem_exchange	if TRUE, enable PMEM exchange during promotion
_enable_pmem_prefetch	if TRUE, enable prefecting from PMEM
_enable_ptime_update_for_sys	Enable/Disable update of user$ for sys
_enable_tenant_id_check	Enable Tenant Id check for database link
_enable_tenant_id_transfer	Enable Tenant Id transfer
_enable_unified_memory	Enable use of unified PGA pool
_endprot_stack_segments	overrun protection for kgh stack segments
_enforce_minimum_password_rollover_time	Enforce minimum PASSWORD_ROLLOVER_TIME of one hour
_enqueue_wall_clock_time	if TRUE, use KSUFTIME timer
_exa_pmemlog_threshold_usec	maximum i/o time (usecs) for enabled Exadata PMEMLog
_failover_svrcsum	enable server checksum to optimize failover
_fb_log_max_rereads	Maximum number of rereads after reading a corrupt flashback block
_fb_recovery_slave_count	Number of recovery slaves to be used by the FLASHBACK DATABASE
_fbda_adv_gbl_bscn_bcast_interval	flashback archiver broadcast interval to advance global barrier SCN
_ffs_in range_scan_threshold	threshold of min percentage of block read to use ffs in rs
_fifteenth_spare_pdb_parameter	fifteenth spare pdb parameter - integer
_fifth_spare_pdb_parameter	fifth spare pdb parameter - integer
_fiftieth_spare_pdb_parameter	fiftieth spare pdb parameter - string list
_fifty-eighth_spare_pdb_parameter	fifty-eighth spare pdb parameter - boolean
_fifty-fifth_spare_pdb_parameter	fifty-fifth spare pdb parameter - boolean
_fifty-first_spare_pdb_parameter	fifty-first spare pdb parameter - boolean
_fifty-fourth_spare_pdb_parameter	fifty-fourth spare pdb parameter - boolean
_fifty-ninth_spare_pdb_parameter	fifty-ninth spare pdb parameter - boolean
_fifty-second_spare_pdb_parameter	fifty-second spare pdb parameter - boolean
_fifty-seventh_spare_pdb_parameter	fifty-seventh spare pdb parameter - boolean
_fifty-sixth_spare_pdb_parameter	fifty-sixth spare pdb parameter - boolean
_fifty-third_spare_pdb_parameter	fifty-third spare pdb parameter - boolean
_first_spare_pdb_parameter	first spare pdb parameter - integer
_fixup_all_apps	Callback to fix up replay state of all applications
_fixup_app_pdb_status_in_root	application name whose PDB application status should be fixed up
_fixup_cdb_apps	Callback to fix up replay state of CDB-wide applications
_force_dax_io_err	Force I/O error on online/standby redo log
_force_pmem_direct_mapped_cache_scan	if TRUE, force PMEM mapped direct path scan to cache path scan
_fortieth_spare_pdb_parameter	fortieth spare pdb parameter - string
_forty-eighth_spare_pdb_parameter	forty-eighth spare pdb parameter - string list
_forty-fifth_spare_pdb_parameter	forty-fifth spare pdb parameter - string list
_forty-first_spare_pdb_parameter	forty-first spare pdb parameter - string list
_forty-fourth_spare_pdb_parameter	forty-fourth spare pdb parameter - string list
_forty-ninth_spare_pdb_parameter	forty-ninth spare pdb parameter - string list
_forty-second_spare_pdb_parameter	forty-second spare pdb parameter - string list
_forty-seventh_spare_pdb_parameter	forty-seventh spare pdb parameter - string list
_forty-sixth_spare_pdb_parameter	forty-sixth spare pdb parameter - string list
_forty-third_spare_pdb_parameter	forty-third spare pdb parameter - string list
_fourteenth_spare_pdb_parameter	fourteenth spare pdb parameter - integer
_fourth_spare_pdb_parameter	fourth spare pdb parameter - integer
_fsdirect_fast_file_create	Allow optimized file creation path for FsDirects
_gc_disable_cell_populate	if TRUE, disable cell ram cache populate
_gc_down_convert_after_write	if TRUE, down-convert lock after a write
_gc_fast_index_split_timeout	fast index split wait timeout
_gc_rdma_connections	maximum number of buffer cache RDMA connections
_gc_undo_header_rdma_read	if TRUE, rdma read of undo headers is enabled
_gcr_disabled_actions	gcr disabled actions list
_gcr_disabled_metrics	gcr disabled metrics list
_gcr_enable_async_slaves	if TRUE, GCR will spawn slave actions asynchronously
_gcr_enable_ktfbue_gather_stats	enable/disable gather stats on X$KTFBUE
_gcr_enable_pdb_abort	if TRUE, GCR will process pdb abort messages
_gcr_ges_cachedres_mult	ges cached resources multiplier
_gcr_ges_longchain_mult	ges longchain multiplier
_gcr_high_cpwt_threshold	longest tolerable ctwr process waits time
_gcr_high_fbwt_threshold	longest tolerable free buffer waits time
_gcr_high_hashlist_latch_nowait_misses	highest hash list get nowait fails tolerable
_gcr_high_hashlist_latch_wait_misses	highest hash list get wait fails tolerable
_gcr_high_lfsci_threshold	longest tolerable log file switch (checkpoint incomplete) wait
_gcs_current_rdma	if greater than 0, rdma read of current blocks is enabled
_gcs_current_rdma_grant_global	if TRUE, enable rdma read of current blocks for global role
_gcs_dynamic_sga_preference	gcs dynamic sga preference
_gcs_spin_check_threshold	spin check attempt count
_gcs_spin_check_time_interval	spin check time interval in seconds
_gcs_verify_antilock	if TRUE, enable anti-lock check
_ges_optimizations	GES optimizations level
_gsm_srvctl_diag_time	gsm invoked srvctl pre-timeout diagnostic time
_gsm_srvctl_timeout	gsm invoked srvctl timeout
_gwm_disable_ra	Oracle internal parameter
_gwm_lagtype	gsm lag type
_gwm_spare1	gsm spare 1
_gwm_sys_ddl	allow DDL as SYS
_gwm_use_srvctl	use srvctl for service mnagement
_gws_catalog_wallet	the sharding catalog has a wallet
_gws_encddl	Encrypt DDL text.
_hang_analyze_elapsed_time_limit	Hang Analyze elapsed time limit in seconds
_hang_bool_spare3	Hang Management bool 3
_hang_cpu_hung_thresh_sec	Hang Manager threshold for resmgr:cpu quantum
_hang_fast_tracked_hang_verification_interval	Hang Manager fast-track hang verification interval
_hang_high_session_count_update_hb_threshold	Hang Manager high session count update heartbeat threshold
_hang_int_spare3	Hang Management int 3
_hang_low_wait_time_cutoff	Hang Management low wait time cutoff in seconds
_hang_mark_some_idle_waits_terminal	Hang Management mark some wait events as terminal waits
_hang_max_local_db_clients_allowed	Hang Manager maximum local db clients allowed
_hang_px_resolution_on_asm_enabled	Hang Management px resolution on ASM enabled
_hang_resolution_partial_hangs_on_asm_enabled	Hang Management resolution of partial hangs on ASM enabled
_hang_sess_enq_wait_blocked_session_threshold	Hang Management session enqueue wait blocked session threshold
_hang_sess_enq_wait_resltn_trig_time	Hang Management session enqueue wait resolution trigger time
_hcs_disable_all_qry_optz	skip all query optimization on generated SQL
_hcs_disable_audit_opt	disable audit optimization
_hcs_disable_av_sql_hint	disable analytic view sql hint
_hcs_disable_calc_union_opt	disable calc union optimization
_hcs_disable_dt_opt_cell_qry	disable cell query optimizations for datatype queries
_hcs_disable_inline	add inline hint to star block
_hcs_disable_merge_fltr_star_opt	disable merge filter star optimization
_hcs_disable_no_bdfltrd_opt	apply no base data filtered optimization
_hcs_disable_prune_unslvd_star_opt	disable prune unsolved star optimization
_hcs_disable_smooth_noop_descendants	perform smooth no-op descendants
_hcs_disable_sql_plan_baselines	disable sql plan baselines
_hcs_disable_use_cache_star_opt	disable use cache star optimization
_hcs_disable_xform_gby	disable transform group by
_hcs_enable_adw	enable ADW
_hcs_enable_av_auto_cache	enable AV auto-cache
_hcs_enable_basetbl_transform	enable base table transform
_hcs_enable_code_trc	enable code tracing
_hcs_enable_cube_join	enable cube join
_hcs_enable_fact_rows	enable fact rows
_hcs_log_max_segments	maximum number of HCS log segments, 0 for unlimited
_hcs_log_segment_size	HCS log segment size in MB
_hcs_max_mdx_cursors	maximum number of MDX cursors
_hcs_mdx_sim_sga_alloc_err	simulate mdx sga allocation error
_hcs_mdx_sim_so_fail	simulate state object failure
_hcs_mdx_sleep_loc	mdx location to sleep for testing
_hcs_sim_sqlopt_err	simulate sql optimization error
_hstpr_prediction_interval	resource SO prediction interval
_hstpr_use_linear_prediction	use session SO lin-reg prediction
_hstpr_use_periodic_prediction	use session SO periodic prediction
_http_port	HTTP port number registered with local listener
_idle_session_scan_frequency	Idle session scan frequency (in seconds)
_ignore_pdb_listener	ignore pdb listener
_ignore_svc_name_conv_mismatch	Suppress ORA-65174 for service_name_convert clause mismatch
_imado_enable_coloptim	Enable AIM Column level optimizations
_imado_enhancements	AIM enhancements
_imr1_slave	IMR1 slave
_imr_slave_debug	IMR slave debug flags
_imtxnrma_table_flags	In-Memory RMA Txn Table cache Flags
_increase_lmd_process	modifying this hidden parameter, will modify the numberof lmd process by the valueof this parameter
_inmemory_dynamic_scans_result_buffers	No. of LWT allocated result buffers per thread
_inmemory_hpk4sql_debug	In-Memory HPK4SQL debug
_inmemory_hpk4sql_filter_threshold	In-Memory HPK4SQL filter threshold
_inmemory_hpk4sql_flags	In-Memory HPK4SQL flags
_inmemory_hpk4sql_kv_seg_size	In-Memory HPK4SQL kv segment size
_inmemory_hpk4sql_partbuf_maxrow	In-Memory HPK4SQL partbuf maxrow
_inmemory_hpk4sql_partbuf_minrow	In-Memory HPK4SQL partbuf minrow
_inmemory_hwm_expansion_rac	If 0, the highwatermark CU is dropped when expanded
_inmemory_hwm_inv_blocks_threshold	If 0, expansion will occur even for very small hwm imcu
_inmemory_hybrid_selectivity_threshold	Selectivity threshold for a qualifying query to enable hybrid IM scans
_inmemory_opaque_contig_space_percent	Contiguous memory for opaque VC as a percent of hard maximum
_inmemory_populate_blocks_threshold	If 0, scan triggers populate for any missing blocks
_inmemory_trickle_populate	Enable inmemory trickle populate
_instant_file_create_exascale	enable instant file creation on Exascale
_ipc_emu_aop_timeout	static emu AOP tinmeout
_ka_lma_msg_wait_count	KA maximum number of requests to retrieve per OSD wait by LMA
_ka_lma_wait_time	KA wait time for skjcxWait call by LMA process in microseconds
_kcb_reused_max	reused array max parameter
_kcrfwrma_flags	KCRFWRMA Flags
_kdlf_fast_move_compressed_lob	kdlf fast move commpressed lobs
_kdlf_layers_cache	enable kdlf securefiles layers cache
_kdli_adaptive_cache_inode	enable adaptive inode cache
_kdli_cache_inode_off_limit	cache_off limit for adaptive inode cache
_kdlwp_memory_check	bug 31354021: memory diagnostics
_kdmado_partial_pop_backoff_mb	AIM Backoff for partial populate
_kebm_preshut_act_enabled	Enable/disable MMON Pre-shutdown Action
_keep_relocated_source_pdb	Move source pdb to unplugged state after relocation
_kffmof_fprate	acceptable false positive rate [1-10000] of the kffmof bloom filter
_kffmof_size	number of entries of the kffmof opened files bloom filter
_kffmop_list_check	enable PGA mop list sanity check
_kgl_bucket_bitvector	Enable creation of PDB bit vector in KGL Hash Buckets
_kgl_bucket_bitvector_clear	Enable clearing library cache bucket bit vector
_kjac_direct_path_enabled	If direct path is enabled for TG
_kkpap_zm_pruning_cache	cache result of recursive zonemap partition pruning query
_kkpox_prtmv_rel_lock	explicitly release PRTMV heap during cursor compile
_kks_always_check_bind_equivalence	Check bind equivalence every time
_kqr_hot_copy_sample_size	number of mutex gets between periodic checks for hot objects
_kqr_hot_copy_sleep_limit	threshold of mutex sleeps to enable object hot copies
_kqr_max_hot_copies	upper limit of object hot copies allowed
_kse_snap_ring_record_min	minimize recorded information in error stack history
_ksfdx_tests	ksfdx testing - INTERNAL USE ONLY!
_ksfqp_row_count	row count of x$ksfqp
_ksipc_ipclw_rcvbuf_mb	Configure IPCLW RCVBUF SIZE (in MB)
_ksmsq_conn_per_epoch	KSMSQ Connections Per Epoch
_kspmx_enabled	KSPMX Is Enabled
_kspmxs_flush_cache_size	KSPMXS flush cache size
_kspmxs_latch_freelists	Number of managed PMEM latch freelists
_kspmxs_latch_usid_map_size	KSPMXS latch usid map size
_kspmxs_max_regions	KSPMXS max regions
_kspmxs_max_waits	KSPMXS max waits
_kspmxs_txn_freelists	Number of PMEM transactions freelists
_kspmxs_upgrade_mutexes	KSPMXS upgrade mutex
_kspmxs_usid_map_size	KSPMXS usid map size
_kspmxs_wait_buckets	KSPMXS wait buckets
_ksr_control_dyn_flags	KSR dyanamic control flags
_ksr_control_flags	KSR control flags
_ksu_proc_percent_target	dynamic process usage target
_ksu_proc_percent_threshold	dynamic process usage threshold
_ksws_alb_block_service	enable ALB Blocking of overloaded service
_ksws_alb_session_age	KSWS ALB Minimum age(seconds) of session to consider marking
_ksws_alb_test_delta_override	KSWS ALB total  sessions after which service is blocked
_ksws_alb_test_drain_timeout	KSWS ALB time in seconds before draining kicks in
_ksws_alb_test_load_balance_frequency	KSWS ALB Load Balance Frequency in deci seconds
_ksws_alb_test_load_percent	KSWS ALB Load Percentage to trigger  marking for draining
_ksws_alb_test_selection_bias	KSWS ALB percentage of sessions to target
_ksws_enable_alb	enable ALB metrics processing
_ksws_fallback_to_root	KSWS Fallback to Root CDB service
_ksws_modsvc_call_out_enabled	modify service call out enabled
_ksws_rlb_cpu_busy_scope	KSWS RLB CPU BUSY SCOPE
_ksws_use_placement_template_attribute	use placement_template attribute
_kswsas_pdb_auto_close_timeout	Close a PDB after the timeout
_ksxp_poll_netintr_timeout	ksxp poll network interrupt timeout in seconds
_ksz_dummy_parameter	Internal spare parameter for ksz.c
_ksz_dummy_parameter2	Internal spare parameter2 for ksz.c
_ktte_ts_shrink_group	tablespace shrink group
_ktte_ts_shrink_interval	tablespace shrink interval
_ldap_use_all_direct_groups_only	LDAP use all direct groups only
_ldap_warning_on_multi_shared_mappings	LDAP warning on multiple shared mappings
_link_ts_force_online	force linked tablespace to be online
_listener_registration_retry_secs	listener registration retry time (in seconds)
_lm_async_da	enable async da requests
_lm_comm_send_proxy_nr_delay	Send proxy delay before sending NULLREQ
_lm_comm_send_proxy_tkt_return	Allow send proxy to return tickets
_lm_comm_slow_op_spx_loop_threshold	GES comm slow spx operation loop threshold in microsec
_lm_comm_tkts_adpt_rsv	Adpative ticketing reserve multiple
_lm_da_win_enable	enable da windowing
_lm_da_window	number of windows in domain action
_lm_da_window_interval	Interval in centiseconds between each domain action window
_lm_default_failure_action	default failure action
_lm_enable_pdb_abort	enable pdb abort as default failure action
_lm_gcs_rht_alloc_size	gcs rht allocation chunk size
_lm_ges_rht_alloc_size	ges rht allocation chunk size
_lm_ges_rht_mem_pct	options to size RHT structures per pdb
_lm_hb_lgio_timeout	LGWR io timeout in seconds
_lm_mp_additional_big_buffers	GES MP extra big buffers per pool
_lm_mp_additional_reg_buffers	GES MP extra regular buffers per pool
_lm_mp_expand_big_pool_percent	GES MP expand big pool
_lm_mp_expand_reg_pool_percent	GES MP expand regular pool
_lm_mp_share_lms_pools	GES MP share LMS pools with critical BGs
_lm_mp_small_lms_pools	GES MP small regular pool for LMS when not sharing
_lm_new_esm	use new enter server mode code
_lm_pdb_weight_opts	options to size RHT structures per pdb
_lm_receiver_type	receiver thread type performing receive function
_lm_recovery_pdbw_reduction	recovery member pdbw reduction
_lm_resource_recycle_cnt	GES: number of resources to recycle optimization
_lm_sp_slave_mode	sendproxy slave operation mode
_lm_wrkr_mode	LMS worker thread mode
_lm_wrkr_slaves	number of LMS worker slaves
_lmhb_max_dynamic_hb	max number of proc heartbeats that can be dynamically monitored
_log_switch_tracing_iterations	no. of iterations to trace after logswitch timeout
_log_switch_tracing_timeout	dbwr to trace after logswitch timeout in secs
_max_dynamic_processes	max dynamic processes count
_max_flashback_shrink_size	maximum size(in KBs) a datafile can be shrunk with flashback DB
_max_gg_extracts	maximum limit for goldengate extract instances
_mdapi_transform_engine	DDL transformation engine
_mle_compilation_errors_are_fatal	failed compilations are fatal for MLE
_mle_compile_immediately	force compilation for MLE
_mle_enable_compilation	enable runtime compilation for MLE
_mv_logical_partition_rewrite_enabled	enable/disable Logical Partition based rewrite
_mv_logical_partition_tracking_enabled	enable/disable Logical Partition Tracking
_mv_master_lock_timeout	timeout that mv create/drop waits to lock the master table
_ndb_enable	Native Database Blockchain Enable
_nineteenth_spare_pdb_parameter	nineteenth spare pdb parameter - integer
_ninth_spare_pdb_parameter	ninth spare pdb parameter - integer
_non_blocking_hard_parse_min_extend_time	minimum additional lifetime added to cursor
_number_ksim_group_req_threshold	ksim maximum number of group operations requests
_numgrans_per_file	Number of granules per SGA file
_nusa_data_containers	list of data containers in the nusa universe
_nusa_metadata_store	metadata store in nusa
_nvmeof_zcopy_enable	Enable Zero Copy for NVMeoF
_object_activity_control	controls tracing for object activity tracking system (OATS)
_object_activity_disable	disables some object activity tracking (OATS)
_object_activity_tracking	enable object activity tracking system (OATS)
_obsolete_result_cache_mode	USERS SHOULD NOT SET THIS! Used for old qksced parameterof result_cache_mode
_ofs_read_buffer_size	OFS read ahead buffer size in bytes
_one-hundred-and-forty-first_spare_parameter	one-hundred-and-forty-first spare parameter - boolean
_one-hundred-and-forty-second_spare_parameter	one-hundred-and-forty-second spare parameter - boolean
_one-hundred-and-forty-third_spare_parameter	one-hundred-and-forty-third spare parameter - boolean
_onl_ddl_progress	track progress of online ddl
_onl_pmo_wait_query	online pmos wait for queries after swapping partitions
_onl_pmo_wait_timeout	online pmos wait for queries after swapping partitions timeout
_online_pmo_global_index_method	Unique global index method for partition maintenance DDLs
_optimize_dvconfig_cloudpdb	Optimize Database Vault setup for cloud PDB
_optimizer_exists_to_any_rewrite	consider exists-to-any rewrite of subqueries
_optimizer_nested_loop_join	favor/unfavor nested loop join
_optimizer_unnest_update_set_subq	enables unnesting of subquery in set for update
_optimizer_use_stats_models	use optimizer statistics extrapolation models
_optimizer_wc_filter_pushdown	enable/disable with clause filter predicate pushdown
_oracle_script_counter	Helper parameter to set the value of _oracle_script counter
_partial_log_preserve_space	use only required space for partial archive logs
_path_prefix_create_dir	Create path in file system for CREATE DIRECTORY with PATH_PREFIX
_pdb_char_set_intconv	Enforce internal_convert for PDB character set conversion
_pdb_clone_preserve_guid	Use same guid for a pdb clone
_pdb_create_use_sysoper_conn	spread file copy slaves across instances
_pdb_datapatch_violation_restricted	Open pdb in restricted mode for datapatch error violation
_pdb_file_copy_affinitize	spread file copy slaves across instances
_pdb_file_copy_buffers	number of buffers to use for pdb file copy
_pdb_hybrid_read_only	Hybrid read only mode allows CDB common user to patch the PDB
_pdb_ktg_buffer_size	KTG buffer size (in KB) to store inmemory traces
_pdb_oper_trace_threshold	PDB operations timing trace threshold
_pdb_oper_trace_threshold_softassert	PDB operations timing threshold soft assert
_pdb_read_only_refresh	allow refresh when pdb is open r/o
_pdb_refresh_use_dblink_to_catalog	Use central catalog for pdb refresh
_pdb_refresh_use_local_logs	Use local logs for pdb refresh
_pdb_small_table_threshold	lower threshold level of table size for direct reads in a pdb
_pdb_transition_clean_bg_delay	delay in GEN0 to transition PDB to clean state
_pmem_exchange_cold_victim_threshold	worthy touch count threshold for a victim buffer to be exchanged into pmem
_pmem_small_table_threshold	lower threshold of PMEM table size as percentage to PMEM cache for direct reads
_pmemfs_alloc_dataptrs	Set PMEMfs to preallocate inode tree
_pmemfs_enable_spacetracking	Enable PMEMfs Space Accounting Checks
_pmemfs_shrink_level	Enable pmemstore shrink
_pmemfs_smallfile_threshold	Block count threshold for metedata
_post_run_job_evaluation	Control if jobs should evaluate at end of execution
_pqq_pdb_load_publish_threshold	difference in percentage controlling PDB load publish
_process_max_pred_increase	process SO max predicted increase
_process_percent_rampup_end	process SO percent rampup end
_process_percent_rampup_start	process SO percent rampup start
_process_prediction_failover_buffer	process prediction failover buffer
_process_save_prediction	save process prediction for next instance startup
_process_so_max_inc	process SO max inc
_profile_sensitive_users	Database Users with restricted password profile
_psdclog_enable	Mandatory Cloud Logging of PL/SQL Utility Packages Usages
_psdclog_threshold	Threshold for Cloud Logging of PL/SQL Utility Packages Usages
_psr_opt	options for standby pdb recovery
_px_adaptive_dist_nij_enabled	enable adaptive distribution methods for left non-inner joins
_px_extended_join_skew_handling	enables extended skew handling for parallel joins
_px_oneslave_per_instance_parse	send parse to one slave per instance
_px_parallelize_non_native_datatype	enable parallelization for non-native datatypes
_remote_http_port	HTTP port number registered with remote listener
_reset_increase_lmd_process	set to true to allow reset of _increase_lmd_process changes
_reset_increase_lms_process	set to true to allow reset of _increase_lms_process changes
_result_cache_do_recycle_period	Timeout value for DOs added through invalidation
_result_cache_global_send	Is global send conditional in RAC?
_result_cache_history_size	memory used to track PL/SQL function history
_result_cache_latch_count	number of result cache latches
_result_cache_load_rate	Simulated global load rate (bytes per 1/100 sec)
_result_cache_object_black_list	object numbers not allowed to use the result cache
_result_cache_use_hash_table	whether to use hash table for object tracking
_root_clone_skip_trigger	Skip trigger in Application Root Clone
_rsrc_cpu_count	CPU Count for allocating resources.
_runtime_index_key_length_check	allow runtime checking of index key length
_runtime_limit_parallel_fptr	run-time limit for for parallel first-pass recovery
_second_spare_pdb_parameter	second spare pdb parameter - integer
_securefile_shrink_enable_nowaitlck	Enable Securefile Shrink NOWAIT row locking
_securefile_shrink_hash_table_limit	Size limit on Securefile Lob Shrink state Hash table
_securefiles_dealloc_cfs	securefiles deallocate directly to CFS
_sess_sign_num_pools	session signature: number of pools
_sess_template_all_overflow	session template: put all attributes into overflow
_sess_template_cache_buckets	session template: number of cache buckets
_sess_template_enabled	session template: enabled
_sess_template_max_cache_size	session template: max cache size (in 1/100% of SGA)
_sess_template_new_lists	session template: number of new lists
_sess_template_purge_time_mins	session template: purge time (in minutes)
_sess_template_spares	session template: spares
_session_limit_percent_cap	session limit percent cap
_session_modp_list	send session's modified parameter list to client
_session_so_max_inc	session SO max inc
_seventeenth_spare_pdb_parameter	seventeenth spare pdb parameter - integer
_seventh_spare_pdb_parameter	seventh spare pdb parameter - integer
_seventieth_spare_pdb_parameter	seventieth spare pdb parameter - boolean
_shard_ddl_policy	DDL execution mode for shards
_shard_sesscache_cnt	enable session caching for shard SQL
_singleton_service_goodness_disabled	singleton srvc goodness
_sixteenth_spare_pdb_parameter	sixteenth spare pdb parameter - integer
_sixth_spare_pdb_parameter	sixth spare pdb parameter - integer
_sixtieth_spare_pdb_parameter	sixtieth spare pdb parameter - boolean
_sixty-eighth_spare_pdb_parameter	sixty-eighth spare pdb parameter - boolean
_sixty-fifth_spare_pdb_parameter	sixty-fifth spare pdb parameter - boolean
_sixty-first_spare_pdb_parameter	sixty-first spare pdb parameter - boolean
_sixty-fourth_spare_pdb_parameter	sixty-fourth spare pdb parameter - boolean
_sixty-ninth_spare_pdb_parameter	sixty-ninth spare pdb parameter - boolean
_sixty-second_spare_pdb_parameter	sixty-second spare pdb parameter - boolean
_sixty-seventh_spare_pdb_parameter	sixty-seventh spare pdb parameter - boolean
_sixty-sixth_spare_pdb_parameter	sixty-sixth spare pdb parameter - boolean
_sixty-third_spare_pdb_parameter	sixty-third spare pdb parameter - boolean
_skip_oradism_check	Switch on all features for the purpose of testing
_skip_sequence_cache_close_immediate	Skip sequence cache flush on pdb shutdown immediate
_smon_ofd_sleep_interval	smon sleep internval for undo ofd test
_spec_replace_locks_body	Lock body when replacing a package specification
_sqlexec_aggregation_settings	runtime settings for aggregation
_sqlexec_hash_aggr_small_mem_blocks	hash aggregation small initial memory footprint number of blocks
_sqlexec_hash_based_distagg_ser_civ_enabled	enable hash based distinct aggregation in serial/CIV queries
_sqlexec_hash_based_set_operation_enabled	enable/disable hash based set operation
_sqlexec_hash_rollup_enabled	enable hash rollup
_sqlexec_use_delayed_unpacking	enable/disable the usage of delayed unpacking
_strict_utl_http_smtp	Enforce strict URL checks on UTL_HTTP and UTL_SMTP Packages
_subquery_pruning_flags	subquery pruning flags
_swat_ver_mv_knob	Knob to control MV/REWRITE behavior
_symbol_no_translation	disable symbol tranlations in call stacks
_sync_error_handler	error handler function for Application Sync
_synchronous_rewrap_rac_ts_keys	if TRUE, synchronously rewrap TS keys in all nodes in MK rekey
_system_memory_simulate	system memory simulation mode, TRUE for hugetlbfs simulation
_tcpinfo_statistics_save_atexit	TCP Info Statistics Save At Exit
_temp_undo_disable_refresh_clone	is temp undo disabled on refreshable clone PDB
_tenth_spare_pdb_parameter	tenth spare pdb parameter - integer
_test_flashback_shrink	test flashback datafile shrink feature
_test_param_13	test parmeter 13 - boolean
_test_param_14	test parmeter 14 - string list
_test_param_15	test parmeter 15 - integer
_test_param_4_1	test parameter 4_1 - nonsys mod. string list
_test_param_pdb_spare	test parameter pdb spare
_test_param_spare	test parameter spare
_third_spare_pdb_parameter	third spare pdb parameter - integer
_thirteenth_spare_pdb_parameter	thirteenth spare pdb parameter - integer
_thirtieth_spare_pdb_parameter	thirtieth spare pdb parameter - string
_thirty-eighth_spare_pdb_parameter	thirty-eighth spare pdb parameter - string
_thirty-fifth_spare_pdb_parameter	thirty-fifth spare pdb parameter - string
_thirty-first_spare_pdb_parameter	thirty-first spare pdb parameter - string
_thirty-fourth_spare_pdb_parameter	thirty-fourth spare pdb parameter - string
_thirty-ninth_spare_pdb_parameter	thirty-ninth spare pdb parameter - string
_thirty-second_spare_pdb_parameter	thirty-second spare pdb parameter - string
_thirty-seventh_spare_pdb_parameter	thirty-seventh spare pdb parameter - string
_thirty-sixth_spare_pdb_parameter	thirty-sixth spare pdb parameter - string
_thirty-third_spare_pdb_parameter	thirty-third spare pdb parameter - string
_trace_suppress	suppresses matching trace for a given substring(prefix)
_trace_suppress_disable	Disable trace suppress feature
_ttc_annotations_level	enable ttc annotations
_twelfth_spare_pdb_parameter	twelfth spare pdb parameter - integer
_twentieth_spare_pdb_parameter	twentieth spare pdb parameter - integer
_twenty-eighth_spare_pdb_parameter	twenty-eighth spare pdb parameter - string
_twenty-fifth_spare_pdb_parameter	twenty-fifth spare pdb parameter - string
_twenty-first_spare_pdb_parameter	twenty-first spare pdb parameter - string
_twenty-fourth_spare_pdb_parameter	twenty-fourth spare pdb parameter - string
_twenty-ninth_spare_pdb_parameter	twenty-ninth spare pdb parameter - string
_twenty-second_spare_pdb_parameter	twenty-second spare pdb parameter - string
_twenty-seventh_spare_pdb_parameter	twenty-seventh spare pdb parameter - string
_twenty-sixth_spare_pdb_parameter	twenty-sixth spare pdb parameter - string
_twenty-third_spare_pdb_parameter	twenty-third spare pdb parameter - string
_txn_spare1	transaction spare variable1
_txn_spare2	transaction spare variable2
_txn_spare3	transaction spare variable3
_undo_ofd_enabled	enable ordered offline drop of undo segments for datafile shrink
_undo_ofd_excess	percent of excess undo segments to offline or drop
_undo_ofd_reserve	percent of excess undo segments to keep online
_unified_pga_block_size	Unified PGA internal block size
_unified_pga_gran_free_timeout	Granule free timeout
_unified_pga_gran_leak_timeout	Granule leak timeout
_unified_pga_list_count	Unified PGA internal list count
_unified_pga_max_pool_size	max size in bytes of the unified pga pool
_upgrade_pdb_on_open	Enable upgrading a PDB automatically on open
_ut_fast_lrg_prediction	use short interval for session SO prediction
_utlfile_dirpath	return Utl_File Accessible
_uts_disable_client_ip_trace	Disables the printing of client IP address in trace files
_uts_force_seclabel_prefix	Force output of trace record security label prefix
_write_renamed_datafile_name	print renamed datafile names to alert log
_xs_sidp_allow_sha1	XS SIDP allow use of SHA1
_zonemap_auto_candidate_table_min_size	Minimum size for a table to be candidate for an automatic zonemap
_zonemap_auto_clustering_ratio	Data clustering ratio in percent for automatic zonemap columns
_zonemap_refresh_within_load	Control the refresh of basic zonemaps during/after data load

 Parameters deprecated in Version 21c in comparison with 19c.

NAME	ISDEP	DESCRIPTION
lock_name_space	TRUE	lock name space used for generating lock names for standby/clone database
instance_groups	TRUE	list of instance group names
resource_manager_cpu_allocation	TRUE	Resource Manager CPU allocation
active_instance_count	TRUE	number of active instances in the cluster database
db_block_buffers	TRUE	Number of database blocks cached in memory
buffer_pool_keep	TRUE	Number of database blocks/latches in keep buffer pool
buffer_pool_recycle	TRUE	Number of database blocks/latches in recycle buffer pool
log_archive_start	TRUE	start archival process on SGA initialization
fast_start_io_target	TRUE	Upper bound on recovery reads
serial_reuse	TRUE	reuse the frame segments
rdbms_server_dn	TRUE	RDBMS's Distinguished Name
cursor_space_for_time	TRUE	use more memory in order to get faster execution
plsql_v2_compatibility	TRUE	PL/SQL version 2.x compatibility flag
plsql_debug	TRUE	PL/SQL debug
background_dump_dest	TRUE	Detached process dump directory
user_dump_dest	TRUE	User process dump directory
commit_write	TRUE	transaction commit log write behaviour
sql_trace	TRUE	enable SQL trace
parallel_adaptive_multi_user	TRUE	enable adaptive setting of degree for multiple user streams
asm_preferred_read_failure_groups	TRUE	preferred read failure groups

 Hidden Parameter Not Available in 21c in comparison with 19c.

PARAMETER	PARAMETER_DESCRIPTION
_arch_sim_mode	Change behavior of local archiving
_asm_enable_parity_datafile_creation	Enable parity datafiles creation
_auto_start_pdb_services	Automatically start all PDB services on PDB Open
_bug29274428_modsvc_call_out_enabled	one-hundred-and-forty-third spare parameter - boolean
_connect_string_params_after_logon_triggers	set connect string session parameters after logon triggers
_connect_string_params_unalterable	make connect string session parameters unalterable
_disable_thread_snapshot	Thread snapshot
_enable_auto_upgrade	Enable automatic PDB upgrade
_gc_async_receive	if TRUE, receive blocks asynchronously
_group_partition_data_for_impdp_ok	data pump import allows DATA_OPTIONS=GROUP_PARTITION_DATA
_hang_enable_nodeeviction	Enable Hang Manager node eviction
_hang_long_wait_time_threshold	Long session wait time threshold in seconds
_hcs_disable_cell_qry_meas_prune_opt	apply measure prune optimization to cell query
_hcs_disable_cell_qry_tmpls	no cell query templates for optimization
_hcs_disable_hord_in_oby_prune	prune levels if HIER_ORDER referenced only in ORDER BY
_hcs_disable_jback_opt_for_hord_in_oby	optimize analytic view joinback for HIER_ORDER
_hcs_disable_level_prune_gby	perform level pruning in group by
_hcs_disable_level_prune_vis_lvs	perform level pruning from visible leaves
_hcs_disable_pushed_preds_in_gen_sql	push sql query predicates into hierarchy targets
_hcs_disable_rmv_unref_top_opt	apply remove unref top blocks optimization to cell query
_hcs_disable_sp_jback_opt	optimize single parent joinback
_hcs_disable_tgt_depths_opt	apply target depths optimization
_hcs_enable_dynamic_cache	enable/disable av cache DYNAMIC definition
_hcs_enable_mem_trck	enable memory tracking
_hcs_enable_multi_parent_gen	generate hcs query using multi-parent aggregation
_kkpo_ctb_allow_vpd	allow VPD predicates in recursive SQL under CREATE TABLE
_ksipc_ipclw_spare_param1	ksipc ipclw spare parameter 1
_log_archive_avoid_memcpy	log archive avoid memcpy
_optimizer_auto_index_allow	Controls Auto Index
_optimizer_quarantine_sql	enable use of sql quarantine
_part_access_version_by_number	use version numbers to access versioned objects for partitioning
_pga_detail_combine_auto	combine auto and manual PGA memory detail snapshots
_reset_maxcap_history	reset maxcap history periods
_securefiles_increase_hbb	securefiles increase hbb
_session_fast_lrg_prediction	use short interval for session SO prediction
_session_prediction_interval	session SO prediction interval
_session_use_linear_prediction	use session SO lin-reg prediction
_session_use_periodic_prediction	use session SO periodic prediction
_show_mgd_recovery_state	Show internal managed recovery state
_size_of_status_table	modifying this hidden parameter, will modify the sizeof the v$gcr_status table
_so_max_inc	SO max inc
_ta_lns_wait_for_arch_log	LNS Wait time for archived version of ORL
_tablespace_encryption_default_algorithm	default tablespace encryption block cipher mode
_unified_audit_flush_interval	Unified Audit SGA Queue Flush Interval
_unified_audit_flush_threshold	Unified Audit SGA Queue Flush Threshold
_workload_attributes_spare_param	connect string workload behavior spare param

 Parameters becomes Obsolete in Version 21c in comparison to 19c.

PARAMETER	PARAMETER_DESCRIPTION
sec_case_sensitive_logon	case sensitive password enabled for logon
REMOTE_OS_AUTHENT	allow non-secure remote clients to use auto-logon accounts
cluster_database_instances	number of instances to use for sizing cluster db SGA structures
_group_partition_data_for_impdp_ok	data pump import allows DATA_OPTIONS=GROUP_PARTITION_DATA
_zonemap_auto_processing	Control the processing of automatic zonemaps
_part_access_version_by_number	use version numbers to access versioned objects for partitioning

 Note: Parameter "_zonemap_auto_processing" was introduced in 20c Preview version and made obsolete in 21c innovation version.

The details of the Parameters are collected from the database views.

View_Name	Details
V$OBSOLETE_PARAMETER	This view shows the information on database Obsolete parameters.
V$PARAMETER	This view shows the information for the parameter value that effects for current session level parameter.
V$PARAMETER2	This view is similar to V$PARAMETER view, only difference is view output for value column. Multiple value for same parameter are shown in this view with multiple rows. Example, multiple values for control_files.
V$PARAMETER_VALID_VALUES	This view displays a list of valid values for list parameters.
V$SPPARAMETER	Its shows the information of SPFILE, if the instance is not brought up with SPFILE then the value of ISSPECIFIED column will be shown as "FALSE". This view also saves the parameter value altered with scope as spfile.
V$SYSTEM_PARAMETER	This view contains the instance level parameters, a new user session inherits the parameters from this view. This view also saves the parameter value altered with scope as memory or both.
V$SYSTEM_PARAMETER2	This view shows the system level parameters.
V$SYSTEM_RESET_PARAMETER	This view Shows the value of a parameter if you run alter system reset to clear it from spfile.
V$SYSTEM_RESET_PARAMETER2	This view is similar to V$SYSTEM_RESET_PARAMETER view, only difference is in output of value column like of V$PARAMETER2.
X$KSPPI	This is a Kernel Service view that have the information on database hidden parameter.
X$KSPPCV	This is a Kernel Service view that have the current session level hidden parameter value.
X$KSPPSV	This is a Kernel Service view that have the system level hidden parameter value.

Conclusion:

After going through this blog the information on new parameter introduced and deprecated will be clear and users will be able to use the parameters for Database Version 21c for building a healthy and well performed database.

In the upcoming blogs I will try to illustrate the performance difference for using the database parameters.

Twitter : https://twitter.com/TapasKarmakar

Linkedin : https://www.linkedin.com/TapasKarmakar

Blog : https://tapaskarmakardba.blogspot.com/

Youtube : https://www.youtube.com/TapasKarmakar

-------------"Keep your data safe so that you can stay safe: – Data security is must."-----------