Oracle Database 12c

The optimization pack for Oracle Database 12c.

Metrics

Memory

Metric	Unit	Description
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

Metric	Unit	Description
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

Metric	Unit	Description
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

Metric	Unit	Description
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

Parameter	Unit	Default value	Domain	Restart	Description
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

Parameter	Unit	Default value	Domain	Restart	Description
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

Parameter	Unit	Default value	Domain	Restart	Description
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

Parameter	Unit	Default value	Domain	Restart	Description
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

Parameter	Unit	Default value	Domain	Restart	Description
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

Parameter	Unit	Default value	Domain	Restart	Description
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

Parameter	Unit	Default value	Domain	Restart	Description
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

Parameter	Unit	Default value	Domain	Restart	Description
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

Formula	Notes
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

Formula	Notes
db.sessions < db.transactions
db.parallel_min_servers < db.parallel_max_servers