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 Special Database Parameters (Extended) 

The following parameters are database parameters that determine special properties of the database instance:

_EVENT_ALIVE_CYCLE

The time in seconds of an event cycle

_MAX_MESSAGE_FILES

Maximum number of trace files that can be open simultaneously

_MAXEVENTS

Maximum number of events stored by the kernel in the cache for processing by the Database Manager

_UNICODE

Parameter for creating a UNICODE-compliant database

You can no longer change this database parameter after you have created the database instance.

CAT_CACHE_SUPPLY

Size of catalog cache memory for all user tasks in pages

DATE_TIME_FORMAT

System default for the date and time format By entering the appropriate information in the database tool (such as the standard_date_mask in the Loader), or by using SQL statements (such as datetimeformat), each user can change the date and time format for a session.

For information about the possible values and syntax, see Date and Time Format.

DEADLOCK_DETECTION

Maximum search level for deadlock detection.

Any deadlocks that are not detected at this search level are only resolved by the parameter REQUEST_TIMEOUT.

If DEADLOCK_DETECTION = 0, deadlock detection is disabled.

DEFAULT_CODE

System default for the code attribute  Applies only to column values of the data type CHAR[ACTER], VARCHAR, and LONG[VARCHAR].

DEVNO_BIT_COUNT

See DEVNO_BIT_COUNT

DIAG_HISTORY_NUM

Number of histories in the <diag_history_path> directory

DIAG_HISTORY_PATH

Directory <diag_history_path> for the histories of log files

The default value is DIAGHISTORY in the run directory of the database instance.

HS_DELAY_TIME_<NNN>

For hot standby systems only; delay in seconds after which the standby component NNN redoes changes that have already been done in the master component

HS_NODE_<NNN>

Computer name/address of the hot standby component NNN.

HSS_NODE_001 is the default for the master component of the standby system.

HS_STORAGE_DLL

For hot standby systems only; name of the library through which the memory management system is addressed

The default is libhsscopy.

HS_SYNC_INTERVAL

For hot standby systems only; minimum period of time (in seconds) between two master component commands for synchronizing the standby components

Any value between 0 and 36000 seconds is allowed. The default is 50.

JOIN_MAXTAB_LEVEL4

Parameter for calculating the join sequence algorithm; see JOIN_SEARCH_LEVEL

JOIN_MAXTAB_LEVEL9

Parameter for calculating the join sequence algorithm; see JOIN_SEARCH_LEVEL

JOIN_SEARCH_LEVEL

Algorithm for the join sequence search; see JOIN_SEARCH_LEVEL

KERNELDIAGSIZE

Size of the log file knldiag in KB

LOAD_BALANCING_CHK

Interval (in seconds) after which the database system checks whether load balancing is needed

£ LOAD_BALANCING_CHK < 600

The default is 0 (load balancing deactivated).

LOG_BACKUP_TO_PIPE

Specifies whether log backup in pipes is permitted

LOG_IO_QUEUE

Size of the log queue in pages

LRU_FOR_SCAN

Specifies whether the entire data cache is used for scans

MAXRGN_REQUEST

Maximum number of attempts a task should make to access a region

If this number is exceeded, the task lets another task access the CPU as long as it belongs to the same user kernel thread.

MAXSERVERTASKS

Determines the number of server tasks that are available, for example, for backups and recoveries

MP_RGN_LOOP

Maximum number of times a task may attempt to access a critical section that has been locked by another task

If this number is exceeded, the accessing task changes its status “Waiting”.

OFFICIAL_NODE

For cluster systems only; official name of the database within the cluster system Defined by the system administrator.

OPTIM_INV_ONLY

Determines whether the Index Only strategy is used for joins

OPTIM_MAX_MERGE

Specifies the change of the optimizer algorithm of the strategies for merging index lists

If the number of pages of an index that need to be merged exceeds the value specified in OPTIM_MAX_MERGE, this index will not be used for an index merging strategy.

REQUEST_TIMEOUT

Maximum wait before a lock is released (in seconds)

This parameter limits the amount of time you have to wait until a lock is lifted by other users for all database sessions. If a lock request cannot be satisfied within the time defined here, a message is returned to the waiting database session. Any changes made previously in the transactions are undone.

SEQUENCE_CACHE

The size of the sequence cache in pages

SESSION_TIMEOUT

Timeout value  for database sessions in seconds

SET_VOLUME_LOCK

Specifies whether a volume can be added or whether it is locked Possible values are Yes and No; the default is Yes.

Yes: When a volume is added, a lock is set that prevents the same volume from being added again, which would cause errors in the system configuration.

No: No lock is set when a volume is added.

UTILITY_PROT_SIZE

Size of the log file dbm.utl in pages

You can display the full list of special database parameters for your database instance and additional information about these parameters using the Database Manager.

 

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