Oracle Concepts - Undocumented Initialization Parameters for 8i

Parameter

Value

Description

_NUMA_instance_mapping

Not Specified

Set of nodes that this instance should run on

_NUMA_pool_size

Not Specified

aggregate size in bytes of NUMA pool

_advanced_dss_features

FALSE

enable advanced DSS features

_affinity_on

FALSE

enable/disable affinity at run time

_all_shared_dblinks

NULL

treat all dblinks as shared

_allocate_creation_order

FALSE

should files be examined in creation order during allocation

_allow_read_only_corruption

FALSE

allow read-only open even if database is corrupt

_allow_resetlogs_corruption

FALSE

allow resetlogs even if it will cause corruption

_always_star_transformation

FALSE

always favor use of star transformation

_arch_io_slaves

0

ARCH I/O slaves

_average_dirties_half_life

2097152

Half life in bytes of first dirties running average

_b_tree_bitmap_plans

FALSE

enable the use of bitmap plans for tables w. only B-tree indexes

_backup_disk_io_slaves

0

BACKUP Disk I/O slaves

_backup_io_pool_size

262144

memory to reserve from the large pool

_bump_highwater_mark_count

0

How many blocks should we allocate per free list on advancing HW

_cleanup_rollback_entries

20

no. of undo entries to apply per transaction cleanup

_close_cached_open_cursors

FALSE

close cursors cached by PL/SQL at each commit

_column_elimination_off

FALSE

turn off predicate-only column elimination

_compatible_no_recovery

0.0.0

Database will be compatible unless crash or media recovery is needed

_complex_view_merging

FALSE

enable complex view merging

_controlfile_enqueue_timeout

900

control file enqueue timeout in seconds

_corrupt_blocks_on_stuck_recovery

0

number of times to corrupt a block when media recovery stuck

_corrupted_rollback_segments

NULL

corrupted undo segment list

_cpu_to_io

NULL

multiplier for converting CPU cost to I/O cost

_cr_server

NULL

if TRUE, enable CR server TRUE (DFS)

_cursor_db_buffers_pinned

78

additional number of buffers a cursor can pin at once

_db_aging_cool_count

1

Touch count set when buffer cooled

_db_aging_freeze_cr

2

Make CR buffers always be FALSE too cold to keep in cache

_db_aging_hot_criteria

2

Touch count which sends a buffer to head of replacement list

_db_aging_stay_count

99

Touch count set when buffer moved to head of replacement list

_db_aging_touch_time

3

Touch count which sends a buffer to head of replacement list

_db_block_cache_clone

FALSE

Always clone data blocks on get (for debugging)

_db_block_cache_map

0

Map / unmap and track reference counts on blocks (for debugging)

_db_block_cache_protect

FALSE

protect database blocks (true only when debugging)

_db_block_hash_buckets

2000

Number of database block hash buckets

_db_block_hi_priority_batch_size

0

Fraction of writes for high priority reasons

_db_block_max_cr_dba

10

Maximum Allowed Number of CR buffers per dba

_db_block_max_scan_cnt

0

Maximum number of buffers to inspect when looking for free

_db_block_med_priority_batch_size

0

Fraction of writes for medium priority reasons

_db_handles

700

System-wide simultaneous buffer operations

_db_handles_cached

5

Buffer handles cached each process

_db_large_dirty_queue

0

Number of buffers which force dirty queue to be written

_db_no_mount_lock

FALSE

do not get a mount lock

_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_writer_chunk_writes

0

Number of writes DBWR should wait for

_db_writer_histogram_statistics

FALSE

maintain dbwr histogram statistics in x$kcbbhs

_db_writer_max_writes

0

Max number of outstanding DB Writer Ios

_db_writer_scan_depth

0

Number of LRU buffers for dbwr to scan when looking for dirty blocks

_db_writer_scan_depth_decrement

0

Subtract from dbwr scan depth when dbwr is working too hard

_db_writer_scan_depth_increment

0

Add to dbwr scan depth when dbwr is behind

_dbwr_async_io

TRUE

Enable dbwriter asynchronous writes

_dbwr_tracing

0

Enable dbwriter tracing

_defer_multiple_waiters

TRUE

if TRUE, defer down converts when there were waiters (DFS)

_disable_incremental_checkpoints

FALSE

Disable incremental checkpoints for thread recovery

_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

TRUE

disable latch-free SCN writes using 64-bit compare & swap

_disable_logging

FALSE

Disable logging

_disable_ntlog_events

FALSE

Disable logging to NT event log

_discrete_transactions_enabled

FALSE

enable OLTP mode

_distributed_lock_timeout

60

number of seconds a distributed transaction waits for a lock

_distributed_recovery_connection_hold_time

200

number of seconds RECO    holds outbound connections open

_domain_index_batch_size

2000

maximum number of rows from one call to domain index fetch routine

_domain_index_dml_batch_size

200

maximum number of rows for one call to domain index dml routines

_dss_cache_flush

TRUE

enable full cache flush for parallel execution

_dynamic_stats_threshold

30

Delay threshold (in seconds) between sending statistics messages

_enable_NUMA_optimization

TRUE

Enable NUMA specific optimizations

_enable_block_level_transaction_recovery

true

enable block level recovery

_enable_cscn_caching

TRUE

enable commit SCN caching for all transactions

_enable_default_affinity

0

to enable default implementation of affinity osds

_enable_list_io

TRUE

Enable List I/O

_enable_multitable_sampling

FALSE

enable multitable sampling

_enqueue_debug_multi_instance

FALSE

Debug enqueue multi-instance

_enqueue_hash

265

enqueue hash table length

_enqueue_hash_chain_latches

2

enqueue hash chain latches

_enqueue_locks

1479

Locks for managed enqueues

_fairness_threshold

4

number of times to CR serve before downgrading lock (DFS)

_fast_full_scan_enabled

FALSE

enable fast full scan

_foreground_locks

TRUE

if TRUE, foregrounds acquire PCM locks (DFS)

_full_pwise_join_enabled

TRUE

enable full partition-wise join when TRUE

_gc_class_locks

0

set locks for the minor classes (DFS)

_gc_latches

4

number of latches per lock process (DFS)

_gc_lck_procs

1

number of background parallel server lock processes to start

_groupby_nopushdown_cut_ratio

3

groupby nopushdown cut ratio

_high_server_threshold

0

high server thresholds

_idl_conventional_index_maintenance

TRUE

enable conventional index maintenance for insert direct load