Exploring Internal Params
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Exploring Internal Params

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Oracle Blocks
Block Type  Description  Block Class Class Description 
1 KTU UNDO HEADER  1 Data block 
2 KTU UNDO BLOCK  2 Sort block 
3 KTT SAVE UNDO HEADER  3  Save undo block 
4 KTT SAVE UNDO BLOCK  4 Segment header 
5 DATA SEGMENT HEADER  5 Save undo header 
6 trans data  6  Free list 
7 Unknown  7 Extent map 
8 Unknown  8  1st level bitmap block 
9 Unknown  9 2nd level bitmap block 
10 DATA SEGMENT FREE LIST BLOCK  10 3rd level bitmap block 
11 Unknown  11  Bitmap block 
12  DATA SEGMENT HEADER WITH FREE LIST BLOCKS  12 Bitmap index block 
13 Compatibility segment  13 File header block 
14 KTU UNDO HEADER W/UNLIMITED EXTENTS  14 Unused 
15 KTT SAVE UNDO HEADER W/UNLIMITED EXTENTS  15  System undo block 
16 DATA SEGMENT HEADER - UNLIMITED  16 System undo block 
17 DATA SEGMENT HEADER WITH FREE LIST BLKS - UNLIMITED  17 Undo header 
18 EXTENT MAP BLOCK  18 Undo block 
19 Unknown  The dynamic performance view V$WAITSTAT returns wait statistics by block class.

SELECT
  inst_id,
  DECODE (indx,
    1,'data block',
    2,'sort block',
    3,'save undo block',
    4,'segment header',
    5,'save undo header',
    6,'free list',
    7,'extent map',
    8,'1st level bmb',
    9,'2nd level bmb',
    10,'3rd level bmb',
    11,'bitmap block',
    12,'bitmap index block',
    13,'file header block',
    14,'unused',
    15,'system undo header',
    16,'system undo block',
    17,'undo header',
    18,'undo block'
  ),  count,  time
FROM x$kcbwait
WHERE indx != 0;
 
20 Unknown 
21  Unknown 
22  DATA SEGMENT FREE LIST BLOCK WITH FREE BLOCK COUNT 
23 BITMAPPED DATA SEGMENT HEADER 
24 BITMAPPED DATA SEGMENT FREELIST 
25 BITMAP INDEX BLOCK 
26 BITMAP BLOCK 
27 LOB BLOCK 
28  KTU BITMAP UNDO HEADER - LIMITED EXTENTS 
29  KTFB Bitmapped File Space Header 
30  KTFB Bitmapped File Space Bitmap 
31  TEMP INDEX BLOCK 
32 FIRST LEVEL BITMAP BLOCK 
33 SECOND LEVEL BITMAP BLOCK 
34 THIRD LEVEL BITMAP BLOCK 
35 PAGETABLE SEGMENT HEADER 
36 PAGETABLE EXTENT MAP BLOCK 
37 EXTENT MAP BLOCK OF SYSTEM MANAGED UNDO SEGMENT 
38  KTU SMU HEADER BLOCK 
39 Unknown 
40  PAGETABLE MANAGED LOB BLOCK 
41 Unknown 
42 Unknown 
43 Unknown 
44 Unknown 
45 Unknown 
46 Unknown 
47 Unknown 
SQL Type Codes Oracle Data Types
Action Name Type Code Name
0 UNKNOWN 1 VARCHAR
1 CREATE TABLE 2 NUMBER
2 INSERT 3 INTEGER
3 SELECT 4 FLOAT
4 CREATE CLUSTER 7 DECIMAL
5 ALTER CLUSTER 9 VARCHAR2
6 UPDATE 12 DATE
7 DELETE 21 REAL
8 DROP CLUSTER 22 DOUBLE PRECISION
9 CREATE INDEX 23 UNSIGNED BINARY INTEGER(8)
10 DROP INDEX 25 UNSIGNED BINARY INTEGER(16)
11 ALTER INDEX 26 UNSIGNED BINARY INTEGER(32)
12 DROP TABLE 27 SIGNED BINARY INTEGER(8)
13 CREATE SEQUENCE 28 SIGNED BINARY INTEGER(16)
14 ALTER SEQUENCE 29 SIGNED BINARY INTEGER(32)
15 ALTER TABLE 32 POINTER
16 DROP SEQUENCE 69 BINARY ROWID
17 GRANT OBJECT 95 RAW
18 REVOKE OBJECT 96 CHAR
19 CREATE SYNONYM 100 BINARY FLOAT
20 DROP SYNONYM 101 BINARY DOUBLE
21 CREATE VIEW 102 PL/SQL REF CURSOR
22 DROP VIEW 104 UROWID
23 VALIDATE INDEX 108 KOKED1
24 CREATE PROCEDURE 108 KOTTBX
25 ALTER PROCEDURE    
26 LOCK 108 KOTMI
27 NO-OP 108 KOTMD
28 RENAME 108 KOTADX
29 COMMENT 108 KOTAD
30 AUDIT OBJECT 108 KOTTD
31 NOAUDIT OBJECT 108 KOKED
32 CREATE DATABASE LINK 110 REF
33 DROP DATABASE LINK 112 CLOB
34 CREATE DATABASE 113 BLOB
35 ALTER DATABASE 114 BFILE
36 CREATE ROLLBACK SEG 115 CFILE
37 ALTER ROLLBACK SEG 185 TIME
38 DROP ROLLBACK SEG 186 TIME WITH TZ
39 CREATE TABLESPACE 187 TIMESTAMP
40 ALTER TABLESPACE 188 TIMESTAMP WITH TZ
41 DROP TABLESPACE 189 INTERVAL YEAR TO MONTH
42 ALTER SESSION 190 INTERVAL DAY TO SECOND
43 ALTER USER 228 NAMED COLLECTION
44 COMMIT 228 NAMED OBJECT
45 ROLLBACK 232 TIMESTAMP WITH LOCAL TZ
46 SAVEPOINT 245 OCTET
47 PL/SQL EXECUTE 246 SMALLINT
48 SET TRANSACTION 247 VARYING ARRAY
49 ALTER SYSTEM 248 TABLE
50 EXPLAIN 250 PL/SQL RECORD
51 CREATE USER 251 PL/SQL COLLECTION
52 CREATE ROLE 252 PL/SQL BOOLEAN
53 DROP USER 256 OID
54 DROP ROLE 257 CONTIGUOUS ARRAY
55 SET ROLE 258 CANONICAL
56 CREATE SCHEMA 259 LOB POINTER
57 CREATE CONTROL FILE 260 PL/SQL POSITIVE
59 CREATE TRIGGER 261 PL/SQL POSITIVEN
60 ALTER TRIGGER 262 PL/SQL ROWID
61 DROP TRIGGER 263 PL/SQL LONG
62 ANALYZE TABLE 264 PL/SQL LONG RAW
63 ANALYZE INDEX 265 PL/SQL BINARY INTEGER
64 ANALYZE CLUSTER 266 PL/SQL PLS INTEGER
65 CREATE PROFILE 267 PL/SQL NATURAL
66 DROP PROFILE 268 PL/SQL NATURALN
67 ALTER PROFILE 269 PL/SQL STRING
68 DROP PROCEDURE  
70 ALTER RESOURCE COST
71 CREATE MATERIALIZED VIEW LOG
72 ALTER MATERIALIZED VIEW LOG
73 DROP MATERIALIZED VIEW LOG The following SQL can used to obtain the data types
SELECT t.typecode,o.name
FROM sys.type$ t, sys.obj$ o
WHERE
BITAND (t.properties, 16) = 16
AND t.toid = o.oid$
ORDER BY t.typecode
74 CREATE MATERIALIZED VIEW
75 ALTER MATERIALIZED VIEW
76 DROP MATERIALIZED VIEW
77 CREATE TYPE
78 DROP TYPE
79 ALTER ROLE
80 ALTER TYPE
81 CREATE TYPE BODY
82 ALTER TYPE BODY
83 DROP TYPE BODY
84 DROP LIBRARY
85 TRUNCATE TABLE
86 TRUNCATE CLUSTER
91 CREATE FUNCTION
92 ALTER FUNCTION
93 DROP FUNCTION
94 CREATE PACKAGE
95 ALTER PACKAGE
96 DROP PACKAGE
97 CREATE PACKAGE BODY
98 ALTER PACKAGE BODY
99 DROP PACKAGE BODY
100 LOGON
101 LOGOFF
102 LOGOFF BY CLEANUP
103 SESSION REC
104 SYSTEM AUDIT
105 SYSTEM NOAUDIT
106 AUDIT DEFAULT
107 NOAUDIT DEFAULT
108 SYSTEM GRANT
109 SYSTEM REVOKE
110 CREATE PUBLIC SYNONYM
111 DROP PUBLIC SYNONYM
112 CREATE PUBLIC DATABASE LINK
113 DROP PUBLIC DATABASE LINK
114 GRANT ROLE
115 REVOKE ROLE
116 EXECUTE PROCEDURE
117 USER COMMENT
118 ENABLE TRIGGER
119 DISABLE TRIGGER
120 ENABLE ALL TRIGGERS
121 DISABLE ALL TRIGGERS
122 NETWORK ERROR
123 EXECUTE TYPE
128 FLASHBACK
129 CREATE SESSION
157 CREATE DIRECTORY
158 DROP DIRECTORY
159 CREATE LIBRARY
160 CREATE JAVA
161 ALTER JAVA
162 DROP JAVA
163 CREATE OPERATOR
164 CREATE INDEXTYPE
165 DROP INDEXTYPE
167 DROP OPERATOR
168 ASSOCIATE STATISTICS
169 DISASSOCIATE STATISTICS
170 CALL METHOD
171 CREATE SUMMARY
172 ALTER SUMMARY
173 DROP SUMMARY
174 CREATE DIMENSION
175 ALTER DIMENSION
176 DROP DIMENSION
177 CREATE CONTEXT
178 DROP CONTEXT
179 ALTER OUTLINE
180 CREATE OUTLINE
181 DROP OUTLINE
182 UPDATE INDEXES
183 ALTER OPERATOR
197 PURGE USER_RECYCLEBIN
198 PURGE DBA_RECYCLEBIN
199 PURGE TABLESAPCE
200 PURGE TABLE
201 PURGE INDEX
202 UNDROP OBJECT
204 FLASHBACK DATABASE
205 FLASHBACK TABLE
206 CREATE RESTORE POINT
207 DROP RESTORE POINT
208 PROXY AUTHENTICATION ONLY
209 DECLARE REWRITE EQUIVALENCE
210 ALTER REWRITE EQUIVALENCE
211 DROP REWRITE EQUIVALENCE

Exploring Hidden Parameters

SQL query for selecting hidden parameters

While connected as SYS, you can use the following query to inspect all hidden parameters for your database:



      SELECT  ksppinm, ksppstvl, ksppdesc
      FROM    x$ksppi x, x$ksppcv y
      WHERE   x.indx = y.indx 
        AND   translate(ksppinm,'_','#') like '#%';

SQL> select KSPPINM,KSPPDESC from x$ksppi where translate(ksppinm,'_','#') like '#%'
/

KSPPINM KSPPSTVL KSPPDESC
_trace_files_public FALSE Create publicly accessible trace files
_latch_recovery_alignment 998 align latch recovery structures
_spin_count 2000 Amount to spin waiting for a latch
_latch_miss_stat_sid 0 Sid of process for which to collect latch stats
_max_sleep_holding_latch 4 max time to sleep while holding a latch
_max_exponential_sleep 0 max sleep during exponential backoff
_use_vector_post TRUE use vector post
_latch_class_0   latch class 0
_latch_class_1   latch class 1
_latch_class_2   latch class 2
_latch_class_3   latch class 3
_latch_class_4   latch class 4
_latch_class_5   latch class 5
_latch_class_6   latch class 6
_latch_class_7   latch class 7
_latch_classes   latch classes override
_session_idle_bit_latches 0 one latch per session or a latch per group of sessions
_ksu_diag_kill_time 5 number of seconds ksuitm waits before killing diag
_num_longop_child_latches 2 number of child latches for long op array
_test_ksusigskip 5 test the function ksusigskip
_disable_kcbhxor_osd FALSE disable kcbh(c)xor OSD functionality
_disable_system_state FALSE disable system state dump
_single_process FALSE run without detached processes
_cpu_count 0 current number of cpu's for this instance
_number_cached_attributes 10 maximum number of cached attributes per instance
_watchpoint_on FALSE is the watchpointing feature turned on?
_ksdxw_num_sgw 10 number of watchpoints to be shared by all processes
_ksdxw_num_pgw 10 number of watchpoints on a per-process basis
_ksdxw_stack_depth 4 number of PCs to collect in the stack when watchpoint is hit
_ksdxw_cini_flg 0 ksdxw context initialization flag
_ksdxw_nbufs 1000 ksdxw number of buffers in buffered mode
_enable_kgh_policy FALSE temporary to disable/enable kgh policy
_NUMA_pool_size Not specified aggregate size in bytes of NUMA pool
_enable_NUMA_optimization TRUE Enable NUMA specific optimizations
_shared_pool_reserved_pct 5 percentage memory of the shared pool allocated for the reserved
_shared_pool_reserved_min_alloc 4400 minimum allocation size in bytes for reserved area of shared poo
_large_pool_min_alloc 3 minimum allocation size in bytes for the large allocation pool
_use_ism TRUE Enable Shared Page Tables - ISM
_lock_sga_areas 0 Lock specified areas of the SGA in physical memory
_NUMA_instance_mapping Not specified Set of nodes that this instance should run on
_kghdsidx_count 1 max kghdsidx count
_realfree_heap_max_size 32768 minimum max total heap size, in Kbytes
_realfree_heap_free_threshold 4194303 threshold for performing real-free, in Kbytes
_realfree_heap_mode 0 mode flags for real-free heap
_use_realfree_heap TRUE use real-free based allocator for PGA memory
_test_param_1 25 test parmeter 1 - integer
_test_param_2   test parameter 2 - string
_test_param_3   test parameter 3 - string
_test_param_4   test parameter 4 - string list
_test_param_5 25 test parmeter 5 - deprecated integer
_test_param_6 0 test parmeter 6 - size (ub8)
_instance_type RDBMS type of instance to be executed
_dbg_proc_startup FALSE debug process startup
_messages 60 message queue resources - dependent on # processes & # buffers
_enqueue_locks 570 locks for managed enqueues
_enqueue_hash 111 enqueue hash table length
_enqueue_debug_multi_instance FALSE debug enqueue multi instance
_enqueue_hash_chain_latches 2 enqueue hash chain latches
_ksi_trace   KSI trace string of lock type(s)
_trace_processes ALL enable KST tracing in process
_trace_archive FALSE start DIAG process
_trace_events   trace events enabled at startup
_trace_buffers ALL:256 trace buffer sizes per process
_trace_flush_processes ALL trace data archived by DIAG for these processes
_trace_file_size 65536 maximum size of trace file (in number of trace records)
_trace_options text,multiple trace data flush options
_nchar_imp_cnv TRUE NLS allow Implicit Conversion between CHAR and NCHAR
_disable_file_locks FALSE disable file locks for control, data, redo log files
_disable_odm FALSE disable odm feature
_open_files_limit 4294967294 Limit on number of files opened by I/O subsystem
_enable_list_io FALSE Enable List I/O
_db_file_direct_io_count 1048576 Sequential I/O buf size
_ioslave_issue_count 500 IOs issued before completion check
_ioslave_batch_count 1 Per attempt IOs picked
_io_slaves_disabled FALSE Do not use I/O slaves
_lgwr_io_slaves 0 LGWR I/O slaves
_arch_io_slaves 0 ARCH I/O slaves
_backup_disk_io_slaves 0 BACKUP Disk I/O slaves
_backup_io_pool_size 262144 memory to reserve from the large pool
_high_server_threshold 0 high server thresholds
_low_server_threshold 0 low server thresholds
_yield_check_interval 100000 interval to check whether actses should yield
_first_spare_parameter   first spare parameter - integer
_second_spare_parameter   second spare parameter - integer
_third_spare_parameter   third spare parameter - integer
_fourth_spare_parameter   fourth spare parameter - string
_fifth_spare_parameter   fifth spare parameter - string
_sixth_spare_parameter   sixth spare parameter - string list
_seventh_spare_parameter   seventh spare parameter - string list
_ksmg_granule_size 8388608 granule size in bytes
_ksmg_granule_locking_status 1 granule locking status
_object_statistics TRUE enable the object level statistics collection
_diag_daemon TRUE start DIAG daemon
_dump_system_state_scope local scope of sysstate dump during instance termination
_lm_lms 0 number of background global cache server processes to start
_lm_dynamic_lms FALSE dynamic lms invocation
_lm_max_lms 0 max. number of background global cache server processes
_lm_min_lms 0 min. number of background global cache server processes
_lm_activate_lms_threshold 100 threshold value to activate an additional lms
_lm_lmd_waittime 4 default wait time for lmd
_lm_lms_waittime 1 default wait time for lms
_lm_procs 127 number of client processes configured for cluster database
_lm_ress 6000 number of resources configured for cluster database
_lm_locks 12000 number of enqueues configured for cluster database
_lm_master_weight 1 master resource weight for this instance
_active_standby_fast_reconfiguration TRUE if TRUE optimize dlm reconfiguration for active/standby OPS
_lm_enq_rcfg TRUE if TRUE enables enqueue reconfiguration
_lm_dynamic_remastering FALSE if TRUE enables dynamic remastering
_lm_xids 139 number of transaction IDs configured for cluster database
_lm_res_part 1289 number of resource partition configured for gcs
_lm_drm_window 32 dynamic remastering bucket window size
_lm_num_pcmhv_latches 0 number of latches covering the PCM HV buckets in cgs
_lm_node_join_opt FALSE cluster database node join optimization in reconfig
_lm_non_fault_tolerant FALSE disable cluster database fault-tolerance mode
_lm_cache_res_cleanup 25 percentage of cached resources should be cleanup
_lm_cache_res_type   cache resource: string of lock types(s)
_lm_cache_lvl0_cleanup 0 how often to cleanup level 0 cache res (in sec)
_lm_send_buffers 10000 number of cluster database send buffers
_lm_rcv_buffer_size 32768 the size of receive buffer
_lm_direct_sends all Processes which will do direct sends
_ogms_home   GMS home directory
_lm_sync_timeout   Synchronization timeout for DLM reconfiguration steps
_lm_ticket_active_sendback   Flow control ticket active sendback threshold
_lm_rcfg_timeout 180000 Reconfiguration timeout
_lm_enq_lock_freelist   Number of ges enqueue element freelist
_lm_enqeue_freelist 3 Number of enqueue freelist
_lm_dd_interval 60 dd time interval in seconds
_dlmtrace   Trace string of lock types(s)
_lm_tx_delta 16 TX lock localization delta
_lm_proc_freeze_timeout 300 reconfiguration: process freeze timeout
_lm_validate_resource_type FALSE if TRUE enables resource name validation
_lm_file_affinity   mapping between file id and master instance number
_lm_share_lock_opt FALSE if TRUE enables share lock optimization
_lm_res_hash_bucket 0 number of resource hash buckets
_lm_msg_batch_size 2048 GES batch message size
_lm_tickets 1000 GES messaging tickets
_lm_msg_cache_thresholds   GES message buffer caching threshold
_lm_msg_cleanup_interval 3000 GES message buffer cleanup interval time
_lm_send_queue_length 5000 GES send queue maximum length
_lm_send_queue_batching TRUE GES send queue message batching
_lm_process_batching TRUE GES implicit process batching for IPC messages
_lm_sq_batch_factor 2 GES send queue minimum batching factor
_abort_recovery_on_join FALSE if TRUE, abort recovery on join reconfigurations
_send_ast_to_foreground TRUE if TRUE, send ast message to foreground
_send_close_with_block TRUE if TRUE, send close with block even with direct sends
_gcs_fast_reconfig TRUE if TRUE, enable fast reconfiguration for gcs locks
_cr_grant_global_role TRUE if TRUE, grant lock for CR requests when block is in global role
_cr_grant_local_role FALSE if TRUE, grant lock for CR using 3way ping when block in local r
_reliable_block_sends FALSE if TRUE, block sends across interconnect are reliable
_skip_assume_msg TRUE if TRUE, skip assume message for consigns at the master
_gcs_resources   number of gcs resources to be allocated
_gcs_latches 128 number of gcs resource hash latches to be allocated
_pcm_shadow_locks   number of pcm shadow locks to be allocated
_side_channel_batch_size 100 number of messages to batch in a side channel message (DFS)
_side_channel_batch_timeout 5 timeout before shipping out all the batched side channel message
_recovery_claim_batch_size 10 number of messages to batch in a recovery claim message (DFS)
_master_direct_sends 31 direct sends for messages from master (DFS)
_cgs_send_timeout 300 CGS send timeout value
_imr_active TRUE Activate Instance Membership Recovery feature
_imr_max_reconfig_delay 300 Maximum Reconfiguration delay (seconds)
_imr_splitbrain_res_wait 600 Maximum wait for split-brain resolution (seconds)
_lm_dynamic_load TRUE dynamic load adjustment
_scn_scheme   SCN scheme
_disable_latch_free_SCN_writes_via_32cas FALSE disable latch-free SCN writes using 32-bit compare & swap
_disable_latch_free_SCN_writes_via_64cas FALSE disable latch-free SCN writes using 64-bit compare & swap
_controlfile_enqueue_timeout 900 control file enqueue timeout in seconds
_db_block_buffers 17622 Number of database blocks cached in memory: hidden parameter
_db_block_cache_protect FALSE protect database blocks (true only when debugging)
_dbwr_tracing 0 Enable dbwriter tracing
_disable_multiple_block_sizes FALSE disable multiple block size support (for debugging)
_small_table_threshold 352 threshold level of table size for direct reads
_db_block_cache_num_umap 0 number of unmapped buffers (for tracking swap calls on blocks)
_db_block_lru_latches 8 number of lru latches
_db_block_granule_interval 10 number of lru latches
_db_block_max_scan_pct 40 Percentage of buffers to inspect when looking for free
_db_writer_scan_depth_pct 25 Percentage of LRU buffers for dbwr to scan when looking for dirt
_db_large_dirty_queue 25 Number of buffers which force dirty queue to be written
_db_writer_max_writes 0 Max number of outstanding DB Writer IOs
_db_writer_chunk_writes 0 Number of writes DBWR should wait for
_db_block_med_priority_batch_size 0 Fraction of writes for medium priority reasons
_db_block_hi_priority_batch_size 0 Fraction of writes for high priority reasons
_db_writer_histogram_statistics FALSE maintain dbwr histogram statistics in x$kcbbhs
_dbwr_async_io TRUE Enable dbwriter asynchronous writes
_dbwr_scan_interval 10 dbwriter scan interval
_db_block_prefetch_quota 10 Prefetch quota as a percent of cache size
_db_block_max_dirty_target 0 Upper bound on modified buffers/recovery reads
_db_block_numa 1 Number of NUMA nodes
_db_percent_hot_default 50 Percent of default buffer pool considered hot
_db_percent_hot_keep 0 Percent of keep buffer pool considered hot
_db_percent_hot_recycle 0 Percent of recycle buffer pool considered hot
_db_aging_hot_criteria 2 Touch count which sends a buffer to head of replacement list
_db_aging_stay_count 0 Touch count set when buffer moved to head of replacement list
_db_aging_cool_count 1 Touch count set when buffer cooled
_db_aging_touch_time 3 Touch count which sends a buffer to head of replacement list
_db_aging_freeze_cr FALSE Make CR buffers always be too cold to keep in cache
_db_block_hash_buckets 35251 Number of database block hash buckets
_db_block_hash_latches 1024 Number of database block hash latches
_db_handles 150 System-wide simultaneous buffer operations
_db_handles_cached 5 Buffer handles cached each process
_wait_for_sync TRUE wait for sync on commit MUST BE ALWAYS TRUE
_db_block_cache_clone FALSE Always clone data blocks on get (for debugging)
_db_block_trace_protect FALSE trace buffer protect calls
_db_block_max_cr_dba 6 Maximum Allowed Number of CR buffers per dba
_trace_buffer_flushes FALSE trace buffer flushes if otrace cacheIO event is set
_trace_multi_block_reads FALSE trace multi_block reads if otrace cacheIO event is set
_trace_cr_buffer_creates FALSE trace cr buffer creates if otrace cacheIO event is set
_write_clones 3 write clones flag
_trace_buffer_gets FALSE trace kcb buffer gets if otrace cacheIO event is set
_check_block_after_checksum TRUE perform block check after checksum if both are turned on
_recovery_percentage 50 recovery buffer cache percentage
_trace_pin_time 0 trace how long a current pin is held
_db_cache_advice_sample_factor 4 cache advisory sampling factor
_db_cache_advice_batch_size 128 cache advisory simulation batch size
_db_mttr_advice ON MTTR advisory
_db_mttr_sim_target   MTTR simulation targets
_db_mttr_sample_factor 64 MTTR simulation sampling factor
_db_mttr_partitions 0 number of partitions for MTTR advisory
_db_mttr_sim_trace_size 256 MTTR simulation trace size
_db_mttr_trace_to_alert FALSE dump trace entries to alert file
_minimum_giga_scn 0 Minimum SCN to start with in 2^30 units
_compatible_no_recovery 0.0.0 Database will be compatible unless crash or media recovery is ne
_db_block_check_for_debug FALSE Check more and dump block before image for debugging
_db_always_check_system_ts TRUE Always perform block check and checksum for System tablespace
_log_checkpoint_recovery_check 0 # redo blocks to verify after checkpoint
_two_pass TRUE enable two-pass thread recovery
_log_archive_buffers 4 Number of buffers to allocate for archiving
_log_archive_buffer_size 2048 Size of each archival buffer in log file blocks
_log_archive_callout   archival callout
_log_archive_net_timeout 0 maximum network wait time in seconds when SYNC=PARALLEL
_log_archive_delta_sync_wait 0 iterative sleep time in centiseconds seconds when SYNC=PARALLEL
_lgwr_max_ns_wt 30 Maximum wait time for lgwr to allow NetServer to progress
_ns_max_flush_wt 30 Flush wait time for NetServer to flush oustanding writes
_lgwr_ns_sim_err 0 Variable to simulate errors lgwrns
_lgwr_ns_nl_min 500 Variable to simulate network latency
_lgwr_ns_nl_max 1000 Variable to simulate network latency
_lgwr_async_io TRUE LGWR Asynchronous IO enabling boolean flag
_lgwr_delay_write FALSE LGWR write delay for debugging
_log_io_size 0 automatically initiate log write if this many redo blocks in buf
_log_switch_timeout 0 Maximum number of seconds redos in the current log could span
_log_buffers_debug FALSE debug redo buffers (slows things down)
_log_buffers_corrupt FALSE corrupt redo buffers before write
_log_debug_multi_instance FALSE debug redo multi instance code
_log_simultaneous_copies 4 number of simultaneous copies into redo buffer(# of copy latches
_disable_logging FALSE Disable logging
_db_file_noncontig_mblock_read_count 11 number of noncontiguous db blocks to be prefetched
_omf enabled enable/disable OMF
_hard_protection FALSE if TRUE enable H.A.R.D specific format changes
_allow_error_simulation FALSE Allow error simulation for testing
_kcl_use_cr TRUE if TRUE, use Fusion CR buffers (DFS)
_kcl_local_file_time 0 how often to check for local files (DFS)
_recovery_asserts FALSE if TRUE, enable expensive recovery sanity checks (DFS)
_gc_integrity_checks TRUE if TRUE, enable expensive integrity checks (DFS)
_keep_recovery_buffers FALSE if TRUE, make recovery buffers current (DFS)
_gc_defer_time 3 how long to defer down converts for hot buffers (DFS)
_gc_latches 4 number of latches per LMS process (DFS)
_kcl_debug TRUE if TRUE, record le history (DFS)
_kcl_index_split TRUE if TRUE, reject pings on blocks in middle of a split (DFS)
_kcl_commit TRUE if TRUE, call kjbcommit (DFS)
_fairness_threshold 4 number of times to CR serve before downgrading lock (DFS)
_interconnect_checksum TRUE if TRUE, checksum interconnect blocks (DFS)
_defer_multiple_waiters TRUE if TRUE, defer down converts when there were waiters (DFS)
_cr_server_log_flush TRUE if TRUE, flush redo log before serving a CR buffer (DFS)
_ping_level 4 fusion ping level (DFS)
_kcl_name_table_latches 16 number of name table latches (DFS)
_async_recovery_reads TRUE if TRUE, issue recovery reads asynchronously (DFS)
_async_recovery_claims TRUE if TRUE, issue recovery claims asynchronously (DFS)
_avoid_prepare TRUE if TRUE, do not prepare a buffer when the master is local (DFS)
_bwr_for_flushed_pi TRUE if TRUE, generate a BWR for a flushed PI (DFS)
_send_requests_to_PI TRUE if TRUE, try to send CR requests to PI buffers (DFS)
_kcl_undo_locks 128 number of locks per undo segment (DFS)
_kcl_undo_grouping 32 grouping for undo block locks (DFS)
_kcl_recovery_read_batch 8 recovery read batch size (DFS)
_kcl_conservative_log_flush FALSE if TRUE, conservatively log flush before CR serving (DFS)
_adaptive_direct_read TRUE Adaptive Direct Read
_disable_incremental_checkpoints FALSE Disable incremental checkpoints for thread recovery
_dump_MTTR_to_trace FALSE Dump High Availability MTTR infromation to CKPT trace file
_log_blocks_during_backup TRUE log block images when changed during backup
_allow_resetlogs_corruption FALSE allow resetlogs even if it will cause corruption
_allow_terminal_recovery_corruption FALSE Finish terminal recovery even if it may cause corruption
_allow_read_only_corruption FALSE allow read-only open even if database is corrupt
_tts_allow_nchar_mismatch FALSE allow plugging in a tablespace with a different national charact
_disable_recoverable_recovery FALSE Disable the new recoverable recovery mechanism
_log_committime_block_cleanout FALSE Log commit-time block cleanout
_ktc_latches 0 number of ktc latches
_allocate_creation_order FALSE should files be examined in creation order during allocation
_log_space_errors TRUE should we report space errors to alert log
_bump_highwater_mark_count 0 how many blocks should we allocate per free list on advancing HW
_last_allocation_period 5 period over which an instance can retain an active level1 bitmap
_inst_locking_period 5 period an instance can retain a newly acquired level1 bitmap
_allocation_update_interval 3 interval at which successful search in L1 should be updated
_ktu_latches 0 number of KTU latches
_rollback_segment_initial 1 starting undo segment number
_rollback_segment_count 0 number of undo segments
_offline_rollback_segments   offline undo segment list
_corrupted_rollback_segments   corrupted undo segment list
_enable_block_level_transaction_recovery TRUE enable block level recovery
_cleanup_rollback_entries 100 no. of undo entries to apply per transaction cleanup
_smu_error_simulation_site 0 site ID of error simulation in KTU code
_smu_error_simulation_type 0 error type for error simulation in KTU code
_collect_undo_stats TRUE Collect Statistics v$undostat
_smu_debug_mode 0 <debug-flag> - set debug event for testing SMU operations
_verify_undo_quota FALSE TRUE - verify consistency of undo quota statistics
_discrete_transactions_enabled FALSE enable OLTP mode
_row_cr FALSE enable row cr for all sql
_smon_internal_errlimit 100 limit of SMON internal errors
_smon_consume_post FALSE consume any extra posts after completion of transaction recovery
_transaction_recovery_servers 0 max number of parallel recovery slaves that may be used
_parallel_recovery_stopat 32767 stop at -position- to step through SMON
_release_insert_threshold 5 maximum number of unusable blocks to unlink from freelist
_walk_insert_threshold 0 maximum number of unusable blocks to walk across freelist
_use_seq_process_cache TRUE whether to use process local seq cache
_reuse_index_loop 5 number of blocks being examine for index block reuse
_kdbl_enable_post_allocation FALSE allocate dbas after populating data buffers
_ignore_desc_in_index FALSE ignore DESC in indexes, sort those columns ascending anyhow
_keep_remote_column_size FALSE remote column size does not get modified
_row_cache_cursors 10 number of cached cursors for row cache management
_kgl_multi_instance_lock TRUE whether KGL to support multi-instance locks
_kgl_multi_instance_pin TRUE whether KGL to support multi-instance pins
_kgl_multi_instance_invalidation TRUE whether KGL to support multi-instance invalidations
_kgl_latch_count 0 number of library cache latches
_kgl_bucket_count 9 index to the bucket count array
_library_cache_advice TRUE whether KGL advice should be turned on
_kglsim_maxmem_percent 5 max percentage of shared pool size to be used for KGL advice
_passwordfile_enqueue_timeout 900 password file enqueue timeout in seconds
_dynamic_rls_policies TRUE rls policies are dynamic
_app_ctx_vers TRUE enable app ctx versioning
_distributed_recovery_connection_hold_time 200 number of seconds RECO holds outbound connections open
_pmon_load_constants 300,192,64,3,10,10,0 server load balancing constants (S,P,D,I,L,C,M)
_dispatcher_rate_ttl   time-to-live for rate statistic (100ths of a second)
_dispatcher_rate_scale   scale to display rate statistic (100ths of a second)
_plsql_dump_buffer_events   conditions upon which the PL/SQL circular buffer is dumped
_job_queue_interval 5 Wakeup interval in seconds for job queue co-ordinator
_optimizer_percent_parallel 101 optimizer percent parallel
_optimizer_search_limit 5 optimizer search limit
_parallel_default_max_instances 1 default maximum number of instances for parallel query
_system_trig_enabled TRUE are system triggers enabled
_kkfi_trace FALSE trace expression substitution
_kolfuseslf FALSE allow kolf to use slffopen
_px_trace none px trace parameter
_parallel_server_idle_time 5 idle time before parallel query server dies
_parallel_server_sleep_time 10 sleep time between dequeue timeouts (in 1/100ths)
_dynamic_stats_threshold 30 delay threshold (in seconds) between sending statistics messages
_parallel_fake_class_pct 0 fake db-scheduler percent used for testing
_px_load_publish_interval 200 interval at which LMON will check whether to publish PX load
_parallel_execution_message_align FALSE Alignment of PX buffers to OS page boundary
_PX_use_large_pool FALSE Use Large Pool as source of PX buffers
_parallel_min_message_pool 64440 minimum size of shared pool memory to reserve for pq servers
_tq_dump_period 0 time period for duping of TQ statistics (s)
_affinity_on TRUE enable/disable affinity at run time
_enable_default_affinity 0 to enable default implementation of affinity osds
_dss_cache_flush FALSE enable full cache flush for parallel execution
_hash_multiblock_io_count 0 number of blocks hash join will read/write at once
_cursor_db_buffers_pinned 585 additional number of buffers a cursor can pin at once
_old_connect_by_enabled FALSE enable/disable old connect by
_table_lookup_prefetch_size 40 table lookup prefetch vector size
_multi_join_key_table_lookup TRUE TRUE iff multi-join-key table lookup prefetch is enabled
_table_lookup_prefetch_thresh 2 table lookup prefetch threshold
_adaptive_fetch_enabled TRUE enable/disable adaptive fetch in parallel group by
_disable_ntlog_events FALSE Disable logging to NT event log
_oracle_trace_events   Oracle TRACE event flags
_oracle_trace_facility_version   Oracle TRACE facility version
_no_objects FALSE no object features are used
_domain_index_batch_size 2000 maximum number of rows from one call to domain index fetch routi
_domain_index_dml_batch_size 200 maximum number of rows for one call to domain index dml routines
_insert_enable_hwm_brokered TRUE during parallel inserts high water marks are brokered
_all_shared_dblinks   treat all dblinks as shared
_close_cached_open_cursors FALSE close cursors cached by PL/SQL at each commit
_init_sql_file %ORACLE_HOME%\RDBMS\ADMIN\SQL.BSQ File containing SQL statements to execute upon database creation
_sort_multiblock_read_count 2 multi-block read count for sort
_sort_space_for_write_buffers 1 tenths of sort_area_size devoted to direct write buffers
_shrunk_aggs_enabled TRUE enable use of variable sized buffers for non-distinct aggregates
_shrunk_aggs_disable_threshold 60 percentage of exceptions at which to switch to full length aggs
_gby_onekey_enabled TRUE enable use of one comparison of all group by keys
_optimizer_undo_changes FALSE undo changes to query optimizer
_sql_connect_capability_table   SQL Connect Capability Table (testing only)
_optimizer_mode_force TRUE force setting of optimizer mode for user recursive SQL also
_explain_rewrite_mode FALSE allow additional messages to be generated during explain rewrite
_query_rewrite_or_error FALSE allow query rewrite, if referenced tables are not dataless
_sort_elimination_cost_ratio 0 cost ratio for sort eimination under first_rows mode
_sql_connect_capability_override 0 SQL Connect Capability Table Override
_always_anti_join CHOOSE always use this method for anti-join when possible
_always_star_transformation FALSE always favor use of star transformation
_b_tree_bitmap_plans TRUE enable the use of bitmap plans for tables w. only B-tree indexes
_column_elimination_off FALSE turn off predicate-only column elimination
_cpu_to_io 0 divisor for converting CPU cost to I/O cost
_optimizer_cost_model CHOOSE optimizer cost model
_optimizer_undo_cost_change 9.2.0 optimizer undo cost change
_optimizer_system_stats_usage 0 system statistics usage
_new_sort_cost_estimate TRUE enables the use of new cost estimate for sort
_complex_view_merging TRUE enable complex view merging
_unnest_subquery TRUE enables unnesting of correlated subqueries
_eliminate_common_subexpr TRUE enables elimination of common sub-expressions
_pred_move_around TRUE enables predicate move-around
_push_join_predicate TRUE enable pushing join predicate inside a view
_push_join_union_view TRUE enable pushing join predicate inside a union view
_fast_full_scan_enabled TRUE enable/disable index fast full scan
_optim_enhance_nnull_detection TRUE TRUE to enable index [fast] full scan more often
_idl_conventional_index_maintenance TRUE enable conventional index maintenance for insert direct load
_enable_cscn_caching FALSE enable commit SCN caching for all transactions
_parallel_broadcast_enabled TRUE enable broadcasting of small inputs to hash and sort merge joins
_px_broadcast_fudge_factor 100 set the tq broadcasting fudge factor percentage
_px_kxib_tracing 0 turn on kxib tracing
_px_granule_size 100000 default size of a rowid range granule (in KB)
_px_async_getgranule FALSE asynchronous get granule in the slave
_px_min_granules_per_slave 13 minimum number of rowid range granules to generate per slave
_px_max_granules_per_slave 100 maximum number of rowid range granules to generate per slave
_px_no_stealing FALSE prevent parallel granule stealing in shared nothing environment
_parallel_adaptive_max_users 1 maximum number of users running with default DOP
_parallel_load_balancing TRUE parallel execution load balanced slave allocation
_parallel_load_bal_unit 0 number of threads to allocate per instance
_pdml_slaves_diff_part TRUE slaves start on different partition when doing index maint
_pdml_gim_sampling 5000 control separation of global index maintenance for PDML
_pdml_gim_staggered FALSE slaves start on different index when doing index maint
_px_dynamic_opt TRUE turn off/on restartable qerpx dynamic optimization
_px_dynamic_sample_size 50 num of samples for restartable qerpx dynamic optimization
_predicate_elimination_enabled TRUE allow predicate elimination if set to TRUE
_groupby_nopushdown_cut_ratio 3 groupby nopushdown cut ratio
_groupby_orderby_combine 5000 groupby/orderby don't combine threshold
_temp_tran_block_threshold 100 number of blocks for a dimension before we temp transform
_temp_tran_cache TRUE determines if temp table is created with cache option
_ordered_semijoin TRUE enable ordered semi-join subquery
_always_semi_join CHOOSE always use this method for semi-join when possible
_ordered_nested_loop TRUE enable ordered nested loop costing
_nested_loop_fudge 100 nested loop fudge
_project_view_columns TRUE enable projecting out unreferenced columns of a view
_no_or_expansion FALSE OR expansion during optimization disabled
_system_index_caching 0 optimizer percent system index caching
_serial_direct_read FALSE enable direct read in serial
_enable_multitable_sampling FALSE enable multitable sampling
_ncmb_readahead_enabled 0 enable multi-block readahead for an index scan
_ncmb_readahead_tracing 0 turn on multi-block readahead tracing
_index_prefetch_factor 100 index prefetching factor
_query_cost_rewrite TRUE perform the cost based rewrite with materialized views
_query_rewrite_2 TRUE perform query rewrite before&after or only after view merging
_query_rewrite_1 TRUE perform query rewrite before&after or only before view merging
_query_rewrite_fudge 90 cost based query rewrite with MVs fudge factor
_query_rewrite_expression TRUE rewrite with cannonical form for expressions
_query_rewrite_jgmigrate TRUE mv rewrite with jg migration
_query_rewrite_fpc TRUE mv rewrite fresh partition containment
_query_rewrite_drj TRUE mv rewrite and drop redundant joins
_query_rewrite_maxdisjunct 257 query rewrite max disjuncts
_query_rewrite_vop_cleanup TRUE prune frocol chain before rewrite after view-merging
_full_pwise_join_enabled TRUE enable full partition-wise join when TRUE
_partial_pwise_join_enabled TRUE enable partial partition-wise join when TRUE
_slave_mapping_enabled TRUE enable slave mapping when TRUE
_slave_mapping_group_size 0 force the number of slave group in a slave mapper
_local_communication_costing_enabled TRUE enable local communication costing when TRUE
_local_communication_ratio 50 set the ratio between global and local communication (0..100)
_parallelism_cost_fudge_factor 350 set the parallelism cost fudge factor
_left_nested_loops_random TRUE enable random distribution method for left of nestedloops
_improved_row_length_enabled TRUE enable the improvements for computing the average row length
_px_index_sampling 200 parallel query sampling for index create (100000 = 100%)
_index_join_enabled TRUE enable the use of index joins
_use_nosegment_indexes FALSE use nosegment indexes in explain plan
_enable_type_dep_selectivity TRUE enable type dependent selectivity estimates
_sqlexec_progression_cost 1000 sql execution progression monitoring cost threshold
_improved_outerjoin_card TRUE improved outer-join cardinality calculation
_optimizer_adjust_for_nulls TRUE adjust selectivity for null values
_optimizer_degree 0 force the optimizer to use the same degree of parallelism
_optimizer_choose_permutation 0 force the optimizer to use the specified permutation
_use_column_stats_for_function TRUE enable the use of column statistics for DDP functions
_subquery_pruning_cost_factor 20 subquery pruning cost factor
_subquery_pruning_reduction 50 subquery pruning reduction factor
_subquery_pruning_enabled TRUE enable the use of subquery predicates to perform pruning
_subquery_pruning_mv_enabled FALSE enable the use of subquery predicates with MVs to perform prunin
_parallel_txn_global FALSE enable parallel_txn hint with updates and deletes
_or_expand_nvl_predicate TRUE enable OR expanded plan for NVL/DECODE predicate
_like_with_bind_as_equality FALSE treat LIKE predicate with bind as an equality predicate
_table_scan_cost_plus_one TRUE bump estimated full table scan and index ffs cost by one
_sortmerge_inequality_join_off FALSE turns off sort-merge join on inequality
_cost_equality_semi_join TRUE enables costing of equality semi-join
_default_non_equality_sel_check TRUE sanity check on default selectivity for like/range predicate
_new_initial_join_orders TRUE enable initial join orders based on new ordering heuristics
_oneside_colstat_for_equijoins TRUE sanity check on default selectivity for like/range predicate
_column_tracking_level 1 column usage tracking
_optim_peek_user_binds TRUE enable peeking of user binds
_mv_refresh_selections TRUE create materialized views with selections and fast refresh
_cursor_plan_enabled TRUE enable collection and display of cursor plans
_minimal_stats_aggregation TRUE prohibit stats aggregation at compile/partition maintenance time
_mv_refresh_eut TRUE refresh materialized views using EUT(partition)-based algorithm
_mav_refresh_consistent_read TRUE refresh materialized views using consistent read snapshot
_mav_refresh_opt 0 optimizations during refresh of materialized views
_mav_refresh_unionall_tables 3 # tables for union all expansion during materialized view refres
_mv_refresh_delta_fraction 10 delta mv as fractional percentage of size of mv
_force_temptables_for_gsets FALSE executes concatenation of rollups using temp tables
_pga_max_size 209715200 Maximum size of the PGA memory for one process
_smm_auto_min_io_size 60 Minimum IO size (in KB) used by sort/hash-join in auto mode
_smm_auto_max_io_size 252 Maximum IO size (in KB) used by sort/hash-join in auto mode
_smm_auto_cost_enabled TRUE if TRUE, use the AUTO size policy cost functions
_smm_control 0 provides controls on the memory manager
_smm_trace 0 Turn on/off tracing for SQL memory manager
_smm_min_size 128 minimum work area size in auto mode
_smm_max_size 3276 maximum work area size in auto mode (serial)
_smm_px_max_size 19659 maximum work area size in auto mode (global)
_smm_bound 0 overwrites memory manager automatically computed bound
_smm_advice_log_size 0 overwrites default size of the PGA advice workarea history log
_smm_advice_enabled TRUE if TRUE, enable v$pga_advice
_gs_anti_semi_join_allowed TRUE enable anti/semi join for the GS query
_mv_refresh_use_stats TRUE pass cardinality hints to refresh queries
_optim_new_default_join_sel TRUE improves the way default equijoin selectivity are computed
_use_new_explain_plan FALSE if TRUE, use the AUTO size policy cost functions
_ldr_io_size 262144 size of write IOs used during a load operation
_unnest_notexists_sq SINGLE unnest NOT EXISTS subquery with one or more tables if possible
_optimizer_dyn_smp_blks 32 number of blocks for optimizer dynamic sampling
_pre_rewrite_push_pred TRUE push predicates into views before rewrite
_optimizer_new_join_card_computation TRUE compute join cardinality using non-rounded input values
_mav_refresh_double_count_prevented FALSE materialized view MAV refreshes avoid double counting
_pct_refresh_double_count_prevented TRUE materialized view PCT refreshes avoid double counting
_mv_refresh_new_setup_disabled FALSE materialized view MV refresh new setup disabling
_load_without_compile NONE Load PL/SQL or Database objects without compilation
_precompute_gid_values TRUE precompute gid values and copy them before returning a row
_union_rewrite_for_gs CHOOSE expand queries with GSets into UNIONs for rewrite
_nested_mav_fast_oncommit_enabled FALSE nested MAV refresh fast on commit allowed
_generalized_pruning_enabled TRUE controls extensions to partition pruning for general predicates
_rowsource_execution_statistics TRUE if TRUE, Oracle will collect rowsource level statistics
_bitmap_or_improvement_enabled TRUE controls extensions to partition pruning for general predicates
_intrapart_pdml_enabled TRUE Enable intra-partition updates/deletes
_optim_adjust_for_part_skews TRUE adjust stats for skews across partitions
_force_datefold_trunc FALSE force use of trunc for datefolding rewrite
_two_pass_reverse_polish_enabled TRUE uses two-pass reverse polish alg. to generate canonical forms
_aq_tm_scanlimit 0 scan limit for Time Managers to clean up IOT
_olap_continuous_trace_file FALSE Specify TRUE to enable continuous OLAP tracing - otherwise only
_olap_parallel_update_threshold 1000 OLAP parallel update threshold in pages
_olap_aggregate_buffer_size 1048576 OLAP Aggregate max buffer size
_olap_aggregate_min_buffer_size 1024 OLAP Aggregate min buffer size
_olap_aggregate_child_fragment_size 32 OLAP Aggregate child fragment size
_olap_aggregate_child_max_size 32768 OLAP Aggregate child list max size
_olap_aggregate_work_per_thread 1024 OLAP Aggregate max work parents
_olap_aggregate_min_thread_status 64 OLAP Aggregate minimum cardinality of dimensions for thread
_olap_aggregate_statlen_thresh 1024 OLAP Aggregate status array usage threshold
_olap_aggregate_worklist_max 5000 OLAP Aggregate max worklists generated at once
_olap_aggregate_max_thread_tuples 5000 OLAP Aggregate max thread tuples creation
_olap_aggregate_store_probability 100 OLAP Aggregate function storeback probability
_olap_aggregate_function_merge_threshold 32768 OLAP Aggregate function merge threshold
_olap_aggregate_function_cache_enabled TRUE OLAP Aggregate function cache enabler
_olap_dimsave_restore_cache_values TRUE OLAP Dimsave restores cached dimension values
_olap_allocate_errorlog_header Dim Source Basis %-8d %-8s %-8b Description -------- -------- -------- ----------- OLAP Allocate Errorlog Header format
_olap_allocate_errorlog_format %8p %8y %8z %e (%n) OLAP Allocate Errorlog Format
_olap_poutlog_echo_to_eventlog FALSE OLAP POutLog copy output to event log (tracefile)
_olap_eif_export_lob_size 2147483647 OLAP EIF Export BLOB size


Links
Server Initialization Parameters
Oracle Internals