Oracle Database 12c
The optimization pack for Oracle Database 12c.
Metrics
Memory
oracle_sga_total_size
bytes
The current memory size of the SGA.
oracle_sga_free_size
bytes
The amount of SGA currently available.
oracle_sga_max_size
bytes
The configured maximum memory size for the SGA.
oracle_pga_target_size
bytes
The configured target memory size for the PGA.
oracle_redo_buffers_size
bytes
The memory size of the redo buffers.
oracle_default_buffer_cache_size
bytes
The memory size for the DEFAULT buffer cache component.
oracle_default_2k_buffer_cache_size
bytes
The memory size for the DEFAULT 2k buffer cache component.
oracle_default_4k_buffer_cache_size
bytes
The memory size for the DEFAULT 4k buffer cache component.
oracle_default_8k_buffer_cache_size
bytes
The memory size for the DEFAULT 8k buffer cache component.
oracle_default_16k_buffer_cache_size
bytes
The memory size for the DEFAULT 16k buffer cache component.
oracle_default_32k_buffer_cache_size
bytes
The memory size for the DEFAULT 32k buffer cache component.
oracle_keep_buffer_cache_size
bytes
The memory size for the KEEP buffer cache component.
oracle_recycle_buffer_cache_size
bytes
The memory size for the RECYCLE buffer cache component.
oracle_asm_buffer_cache_size
bytes
The memory size for the ASM buffer cache component.
oracle_shared_io_pool_size
bytes
The memory size for the IO pool component.
oracle_java_pool_size
bytes
The memory size for the Java pool component.
oracle_large_pool_size
bytes
The memory size for the large pool component.
oracle_shared_pool_size
bytes
The memory size for the shared pool component.
oracle_streams_pool_size
bytes
The memory size for the streams pool component.
oracle_buffer_cache_hit_ratio
percent
How often a requested block has been found in the buffer cache without requiring disk access.
Event waits
oracle_wait_class_commit
percent
The percentage of time spent waiting on the events of class 'Commit'.
oracle_wait_class_concurrency
percent
The percentage of time spent waiting on the events of class 'Concurrency'.
oracle_wait_class_system_io
percent
The percentage of time spent waiting on the events of class 'System I/O'.
oracle_wait_class_user_io
percent
The percentage of time spent waiting on the events of class 'User I/O'.
oracle_wait_class_other
percent
The percentage of time spent waiting on the events of class 'Other'.
oracle_wait_class_scheduler
percent
The percentage of time spent waiting on the events of class 'Scheduler'.
oracle_wait_class_idle
percent
The percentage of time spent waiting on the events of class 'Idle'.
oracle_wait_class_application
percent
The percentage of time spent waiting on the events of class 'Application'.
oracle_wait_class_network
percent
The percentage of time spent waiting on the events of class 'Network'.
oracle_wait_class_configuration
percent
The percentage of time spent waiting on the events of class 'Configuration'.
oracle_wait_event_log_file_sync
percent
The percentage of time spent waiting on the 'log file sync' event.
oracle_wait_event_log_file_parallel_write
percent
The percentage of time spent waiting on the 'log file parallel write' event.
oracle_wait_event_log_file_sequential_read
percent
The percentage of time spent waiting on the 'log file sequential read' event.
oracle_wait_event_enq_tx_contention
percent
The percentage of time spent waiting on the 'enq: TX - contention' event.
oracle_wait_event_enq_tx_row_lock_contention
percent
The percentage of time spent waiting on the 'enq: TX - row lock contention' event.
oracle_wait_event_latch_row_cache_objects
percent
The percentage of time spent waiting on the 'latch: row cache objects' event.
oracle_wait_event_latch_shared_pool
percent
The percentage of time spent waiting on the 'latch: shared pool' event.
oracle_wait_event_resmgr_cpu_quantum
percent
The percentage of time spent waiting on the 'resmgr:cpu quantum' event.
oracle_wait_event_sql_net_message_from_client
percent
The percentage of time spent waiting on the 'SQL*Net message from client' event.
oracle_wait_event_rdbms_ipc_message
percent
The percentage of time spent waiting on the 'rdbms ipc message' event.
oracle_wait_event_db_file_sequential_read
percent
The percentage of time spent waiting on the 'db file sequential read' event.
oracle_wait_event_log_file_switch_checkpoint_incomplete
percent
The percentage of time spent waiting on the 'log file switch (checkpoint incomplete)' event.
oracle_wait_event_row_cache_lock
percent
The percentage of time spent waiting on the 'row cache lock' event.
oracle_wait_event_buffer_busy_waits
percent
The percentage of time spent waiting on the 'buffer busy waits' event.
oracle_wait_event_db_file_async_io_submit
percent
The percentage of time spent waiting on the 'db file async I/O submit' event.
Sessions
oracle_sessions_active_user
sessions
The number of active user sessions.
oracle_sessions_inactive_user
sessions
The number of inactive user sessions.
oracle_sessions_active_background
sessions
The number of active background sessions.
oracle_sessions_inactive_background
sessions
The number of inactive background sessions.
Other metrics
oracle_calls_execute_count
calls
Total number of calls (user and recursive) that executed SQL statements.
oracle_tuned_undoretention
seconds
The amount of time for which undo will not be recycled from the time it was committed.
oracle_max_query_length
seconds
The length of the longest query executed.
oracle_transaction_count
transactions
The total number of transactions executed within the period.
oracle_sso_errors
errors/s
The number of ORA-01555 (snapshot too old) errors raised per second.
oracle_redo_log_space_requests
requests
The number of times a user process waits for space in the redo log file, usually caused by checkpointing or log switching.
Parameters
Memory
bitmap_merge_area_size
kilobytes
1048576
0 → 2147483647
yes
The amount of memory Oracle uses to merge bitmaps retrieved from a range scan of the index.
create_bitmap_area_size
megabytes
8388608
0 → 1073741824
yes
Size of create bitmap buffer for bitmap index. Relevant only for systems containing bitmap indexes.
db_block_size
bytes
8192
2048 → 32768
yes
The size of Oracle database blocks. The value of this parameter can be changed only when the database is first created.
db_cache_size
megabytes
48
0 → 2097152
no
The size of the DEFAULT buffer pool for standard block size buffers. The value must be at least 4M * cpu number.
db_2k_cache_size
megabytes
0
0 → 2097152
no
Size of cache for 2K buffers.
db_4k_cache_size
megabytes
0
0 → 2097152
no
Size of cache for 4K buffers.
db_8k_cache_size
megabytes
0
0 → 2097152
no
Size of cache for 8K buffers.
db_16k_cache_size
megabytes
0
0 → 2097152
no
Size of cache for 16K buffers.
db_32k_cache_size
megabytes
0
0 → 2097152
no
Size of cache for 32K buffers.
hash_area_size
kilobytes
131072
0 → 2147483647
yes
Maximum size of in-memory hash work area maximum amount of memory.
java_pool_size
megabytes
24
0 → 65536
no
The size of the Java pool. If SGA_TARGET is set, this value represents the minimum value for the memory pool.
large_pool_size
megabytes
0
0 → 65536
no
The size of large pool allocation heap.
lock_sga
FALSE
TRUE, FALSE
yes
Lock the entire SGA in physical memory.
memory_max_target
megabytes
8192
152 → 2097152
yes
The maximum value to which a DBA can set the MEMORY_TARGET initialization parameter.
memory_target
megabytes
6144
0 → 2097152
no
Oracle systemwide usable memory. The database tunes memory to the MEMORY_TARGET value, reducing or enlarging the SGA and PGA as needed.
pga_aggregate_limit
megabytes
2048
0 → 4194304
no
The limit on the aggregate PGA memory consumed by the instance.
pga_aggregate_target
megabytes
1024
0 → 4194304
no
The target aggregate PGA memory available to all server processes attached to the instance.
result_cache_max_result
percent
5
0 → 100
no
Maximum result size as a percent of cache the size.
result_cache_max_size
megabytes
0
0 → 65536
no
The maximum amount of SGA memory that can be used by the Result Cache.
result_cache_remote_expiration
minutes
0
0 → 10000
no
The expiration in minutes of remote objects. High values may cause stale answers.
sga_max_size
megabytes
8192
0 → 2097152
yes
The maximum size of the SGA for the lifetime of the instance.
sga_min_size
megabytes
2920
0 → 1048576
no
The guaranteed SGA size for a pluggable database (PDB). When SGA_MIN_SIZE is set for a PDB, it guarantees the specified SGA size for the PDB.
sga_target
megabytes
5840
0 → 2097152
no
The total size of all SGA components, acts as the minimum value for the size of the SGA.
shared_pool_reserved_size
megabytes
128
1 → 2048
yes
The shared pool space reserved for large contiguous requests for shared pool memory.
shared_pool_size
megabytes
0
0 → 65536
no
The size of the shared pool.
sort_area_retained_size
kilobytes
0
0 → 2147483647
no
The maximum amount of the User Global Area memory retained after a sort run completes.
sort_area_size
kilobytes
64
0 → 8388608
no
The maximum amount of memory Oracle will use for a sort. If more space is required then temporary segments on disks are used.
streams_pool_size
megabytes
0
0 → 65536
no
Size of the streams pool.
use_large_pages
TRUE
ONLY, FALSE, TRUE
yes
Enable the use of large pages for SGA memory.
Redo
commit_logging
BATCH
IMMEDIATE, BATCH
no
Control how redo is batched by Log Writer.
log_archive_max_processes
processes
4
1 → 30
no
Maximum number of active ARCH processes.
log_buffer
megabytes
16
2 → 8192
yes
The amount of memory that Oracle uses when buffering redo entries to a redo log file.
log_checkpoint_interval
blocks
0
0 → 2147483647
no
The maximum number of log file blocks between incremental checkpoints.
log_checkpoint_timeout
seconds
1800
0 → 2147483647
no
Maximum time interval between checkpoints. Guarantees a no buffer remains dirty for more than the specified time.
Undo
undo_retention
seconds
900
0 → 2147483647
no
Low threshold value of undo retention.
undo_management
AUTO
MANUAL, AUTO
yes
Instance runs in SMU mode if TRUE, else in RBU mode
temp_undo_enabled
FALSE
TRUE, FALSE
no
Split undo log into temporary (temporary objects) and permanent (persistent objects) undo log.
Optimizer
optimizer_adaptive_plans
FALSE
TRUE, FALSE
no
Controls adaptive plans, execution plans built with alternative choices based on collected statistics.
optimizer_adaptive_statistics
FALSE
TRUE, FALSE
no
Enable the optimizer to use adaptive statistics for complex queries.
optimizer_capture_sql_plan_baselines
FALSE
TRUE, FALSE
no
Automatic capture of SQL plan baselines for repeatable statements
optimizer_dynamic_sampling
2
0 → 11
no
Controls both when the database gathers dynamic statistics, and the size of the sample that the optimizer uses to gather the statistics.
optimizer_features_enable
11.2.0.4
11.2.0.4.1, 11.2.0.4, 11.2.0.3, 11.2.0.2, 11.2.0.1, 11.1.0.7, 11.1.0.6, 10.2.0.5, 10.2.0.4, 10.2.0.3, 10.2.0.2, 10.2.0.1, 10.1.0.5, 10.1.0.4, 10.1.0.3, 10.1.0, 9.2.0.8, 9.2.0, 9.0.1, 9.0.0, 8.1.7, 8.1.6, 8.1.5, 8.1.4, 8.1.3, 8.1.0, 8.0.7, 8.0.6, 8.0.5, 8.0.4, 8.0.3, 8.0.0
no
Enable a series of optimizer features based on an Oracle release number.
optimizer_index_caching
0
0 → 100
no
Adjust the behavior of cost-based optimization to favor nested loops joins and IN-list iterators.
optimizer_index_cost_adj
100
1 → 10000
no
Tune optimizer behavior for access path selection to be more or less index friendly.
optimizer_inmemory_aware
TRUE
TRUE, FALSE
no
Enables all of the optimizer cost model enhancements for in-memory.
optimizer_mode
ALL_ROWS
ALL_ROWS, FIRST_ROWS, FIRST_ROWS_1, FIRST_ROWS_10, FIRST_ROWS_100, FIRST_ROWS_1000
no
The default behavior for choosing an optimization approach for the instance.
optimizer_use_invisible_indexes
FALSE
TRUE, FALSE
no
Enable or disables the use of invisible indexes.
optimizer_use_pending_statistics
FALSE
TRUE, FALSE
no
Control whether the optimizer uses pending statistics when compiling SQL statements.
optimizer_use_sql_plan_baselines
TRUE
TRUE, FALSE
no
Enables the use of SQL plan baselines stored in SQL Management Base.
Approximate execution
approx_for_aggregation
FALSE
TRUE, FALSE
no
Replace exact query processing for aggregation queries with approximate query processing.
approx_for_count_distinct
FALSE
TRUE, FALSE
no
Automatically replace COUNT (DISTINCT expr) queries with APPROX_COUNT_DISTINCT queries.
approx_for_percentile
NONE
NONE, PERCENTILE_CONT, PERCENTILE_CONT DETERMINISTIC, PERCENTILE_DISC, PERCENTILE_DISC DETERMINISTIC, ALL, ALL DETERMINISTIC
no
Converts exact percentile functions to their approximate percentile function counterparts.
Parallel processing
parallel_max_servers
processes
0
0 → 32767
no
The maximum number of parallel execution processes and parallel recovery processes for an instance.
parallel_min_servers
processes
0
0 → 2000
no
The minimum number of execution processes kept alive to service parallel statements.
parallel_threads_per_cpu
2
1 → 128
no
Number of parallel execution threads per CPU.
Resources
cpu_count
cpus
0
0 → 512
no
Number of CPUs available for the Oracle instance to use.
db_files
files
200
100 → 20000
yes
The maximum number of database files that can be opened for this database. This may be subject to OS constraints.
open_cursors
cursors
50
0 → 65535
no
The maximum number of open cursors (handles to private SQL areas) a session can have at once.
open_links
connections
4
0 → 32768
yes
The maximum number of concurrent open connections to remote databases in one session.
open_links_per_instance
connections
4
0 → 2147483647
yes
Maximum number of migratable open connections globally for each database instance.
processes
processes
800
6 → 20000
yes
The maximum number of OS user processes that can simultaneously connect to Oracle.
read_only_open_delayed
FALSE
TRUE, FALSE
yes
Delay opening of read only files until first access.
sessions
sessions
1262
1 → 65536
no
The maximum number of sessions that can be created in the system, effectively the maximum number of concurrent users in the system.
transactions
transactions
1388
4 → 2147483647
yes
The maximum number of concurrent transactions.
Other parameters
audit_sys_operations
FALSE
TRUE, FALSE
yes
Enable sys auditing
audit_trail
NONE
NONE, OS, DB, DB, EXTENDED, XML, XML, EXTENDED
yes
Configure system auditing.
gcs_server_processes
processes
0
0 → 100
yes
The number of background GCS server processes to serve the inter-instance traffic among Oracle RAC instances.
java_jit_enabled
TRUE
TRUE, FALSE
no
Enables the Just-in-Time (JIT) compiler for the Oracle Java Virtual Machine.
fast_start_mttr_target
seconds
0
0 → 3600
no
number of seconds the database should take to perform crash recovery of a single instance. This parameter impacts the time between checkpoints.
recyclebin
ON
ON, OFF
no
Allow recovering of dropped tables.
statistics_level
TYPICAL
BASIC, TYPICAL, ALL
no
Level of collection for database and operating system statistics.
transactions_per_rollback_segment
5
1 → 10000
yes
Expected number of active transactions per rollback segment.
filesystemio_options
asynch
none, setall, directIO, asynch
yes
Specifies I/O operations for file system files.
Values and domain suggestions
The following parameters require their ranges or default values to be updated according to the described rules:
Memory
Parameter
Default value
Domain
db_cache_size
MAX(48MB, 4MB * cpu_num)
java_pool_size
24MB if SGA_TARGET is not set
0 if SGA_TARGET is set, meaning the lower bound for the pool is automatically determined
shared_pool_reserved_size
5% of shared_pool_size
shared_pool_size
0 if sga_target is set, 128MB otherwise
shared_pool_reserved_size
upper bound can’t exceed half the size of shared_pool_size
pga_aggregate_target
MAX(10MB, 0.2*sga_target)
pga_aggregate_limit
MEMORY_MAX_TARGET if MEMORY_TARGET explicit or
2 * PGA_AGGREGATE_TARGET if PGA_AGGREGATE_TARGET explicit or
0.9 * ({MEMORY_AVAILABLE} - SGA)
at least MAX(2GB, 3MB * db.processes)
hash_area_size
2 * sort_area_size
Resources
Parameter
Default value
Domain
cpu_count
should match the available CPUs 0 to let the Oracle engine automatically determine the value
must not exceed the available CPUs
gcs_server_processes
0 if cluster_database=false
1 for 1-3 CPUs, or if ASM
2 for 4-15 CPUs2+lower(CPUs/32) for 16+ CPUs
parallel_min_servers
CPU_COUNT * PARALLEL_THREADS_PER_CPU * 2
parallel_max_servers
PARALLEL_THREADS_PER_CPU * CPU_COUNT * concurrent_parallel_users * 5
sessions
1.1 * processes + 5
must be at least equal to the default value
transactions
1.1 * sessions
Constraints
The following tables show a list of constraints that may be required in the definition of the study, depending on the tuned parameters.
Memory
db.memory_target <= db.memory_max_target && db.memory_max_target < {MEMORY_AVAILABLE}
Add when tuning automatic memory management
db.sga_max_size + db.pga_aggregate_limit <= db.memory_max_target
Add when tuning SGA and PGA
db.sga_target + db.pga_aggregate_target <= db.memory_target
Add when tuning SGA and PGA
db.sga_target <= db.sga_max_size
Add when tuning SGA
db.db_cache_size + db.java_pool_size + db.large_pool_size + db.log_buffer + db.shared_pool_size + db.streams_pool_size < db.sga_max_size
Add when tuning SGA areas
db.pga_aggregate_target <= db.pga_aggregate_limit
Add when tuning PGA
db.shared_pool_reserved_size <= 0.5 * db.shared_pool_size
db.sort_area_retained_size <= db.sort_area_size
Other constraints
db.sessions < db.transactions
db.parallel_min_servers < db.parallel_max_servers
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