InstanceParameters members

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This class provides properties to set and get system parameters on an ESENT instance. This class provides static properties to set and get per-instance ESENT system parameters.

The InstanceParameters type exposes the following members.

Constructors

	Name	Description
	InstanceParameters	Initializes a new instance of the InstanceParameters class.

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Properties

	Name	Description
	AlternateDatabaseRecoveryDirectory	Gets or sets the relative or absolute file system path of the a folder where crash recovery or a restore operation can find the databases referenced in the transaction log in the specified folder.
	BaseName	Gets or sets the three letter prefix used for many of the files used by the database engine. For example, the checkpoint file is called EDB.CHK by default because EDB is the default base name.
	CachedClosedTables	Gets or sets a value giving the number of B+ Tree resources cached by the instance after the tables they represent have been closed by the application. Large values for this parameter will cause the database engine to use more memory but will increase the speed with which a large number of tables can be opened randomly by the application. This is useful for applications that have a schema with a very large number of tables. Supported on Windows Vista and up. Ignored on Windows XP and Windows Server 2003.
	CachePriority	Gets or sets the per-instance property for relative cache priorities (default = 100).
	CheckpointDepthMax	Gets or sets the threshold in bytes for about how many transaction log files will need to be replayed after a crash. If circular logging is enabled using CircularLog then this parameter will also control the approximate amount of transaction log files that will be retained on disk.
	CircularLog	Gets or sets a value indicating whether circular logging is on. When circular logging is off, all transaction log files that are generated are retained on disk until they are no longer needed because a full backup of the database has been performed. When circular logging is on, only transaction log files that are younger than the current checkpoint are retained on disk. The benefit of this mode is that backups are not required to retire old transaction log files.
	CleanupMismatchedLogFiles	Gets or sets a value indicating whether JetInit fails when the database engine is configured to start using transaction log files on disk that are of a different size than what is configured. Normally, JetInit(JET_INSTANCE) will successfully recover the databases but will fail with LogFileSizeMismatchDatabasesConsistent to indicate that the log file size is misconfigured. However, when this parameter is set to true then the database engine will silently delete all the old log files, start a new set of transaction log files using the configured log file size. This parameter is useful when the application wishes to transparently change its transaction log file size yet still work transparently in upgrade and restore scenarios.
	CreatePathIfNotExist	Gets or sets a value indicating whether ESENT will silently create folders that are missing in its filesystem paths.
	DbExtensionSize	Gets or sets the number of pages that are added to a database file each time it needs to grow to accommodate more data.
	DbScanIntervalMaxSec	Gets or sets the maximum interval to allow the database scan to finish, in seconds.
	DbScanIntervalMinSec	Gets or sets the minimum interval to repeat the database scan, in seconds.
	DbScanThrottle	Gets or sets the throttling of the database scan, in milliseconds.
	EnableDbScanInRecovery	Gets or sets a value indicating whether Database Maintenance should run during recovery.
	EnableDBScanSerialization	Gets or sets a value indicating whether database Maintenance serialization is enabled for databases sharing the same disk.
	EnableIndexChecking	Gets or sets a value indicating whether JetAttachDatabase(JET_SESID, String, AttachDatabaseGrbit) will check for indexes that were build using an older version of the NLS library in the operating system.
	EnableOnlineDefrag	Gets or sets a value indicating whether online defragmentation is enabled.
	EventSource	Gets or sets an application specific string that will be added to any event log messages that are emitted by the database engine. This allows easy correlation of event log messages with the source application. By default the host application executable name will be used.
	EventSourceKey	Gets or sets the name of the event log the database engine uses for its event log messages. By default, all event log messages will go to the Application event log. If the registry key name for another event log is configured then the event log messages will go there instead.
	LogBuffers	Gets or sets the amount of memory used to cache log records before they are written to the transaction log file. The unit for this parameter is the sector size of the volume that holds the transaction log files. The sector size is almost always 512 bytes, so it is safe to assume that size for the unit. This parameter has an impact on performance. When the database engine is under heavy update load, this buffer can become full very rapidly. A larger cache size for the transaction log file is critical for good update performance under such a high load condition. The default is known to be too small for this case. Do not set this parameter to a number of buffers that is larger (in bytes) than half the size of a transaction log file.
	LogFileDirectory	Gets or sets the relative or absolute file system path of the folder that will contain the transaction logs for the instance.
	LogFileSize	Gets or sets the size of the transaction log files. This parameter should be set in units of 1024 bytes (e.g. a setting of 2048 will give 2MB logfiles).
	MaxCursors	Gets or sets the number of cursor resources reserved for this instance. A cursor resource directly corresponds to a JET_TABLEID.
	MaxOpenTables	Gets or sets the number of B+ Tree resources reserved for this instance.
	MaxSessions	Gets or sets the number of sessions resources reserved for this instance. A session resource directly corresponds to a JET_SESID.
	MaxTemporaryTables	Gets or sets the number of temporary table resources for use by an instance. This setting will affect how many temporary tables can be used at the same time. If this system parameter is set to zero then no temporary database will be created and any activity that requires use of the temporary database will fail. This setting can be useful to avoid the I/O required to create the temporary database if it is known that it will not be used.
	MaxTransactionSize	Gets or sets the percentage of version store that can be used by oldest transaction before VersionStoreOutOfMemory (default = 100).
	MaxVerPages	Gets or sets the maximum number of version store pages reserved for this instance.
	NoInformationEvent	Gets or sets a value indicating whether informational event log messages that would ordinarily be generated by the database engine will be suppressed.
	OneDatabasePerSession	Gets or sets a value indicating whether only one database is allowed to be opened using JetOpenDatabase by a given session at one time. The temporary database is excluded from this restriction.
	PageTempDBMin	Gets or sets the initial size of the temporary database. The size is in database pages. A size of zero indicates that the default size of an ordinary database should be used. It is often desirable for small applications to configure the temporary database to be as small as possible. Setting this parameter to PageTempDBSmallest will achieve the smallest temporary database possible.
	PreferredVerPages	Gets or sets the preferred number of version store pages reserved for this instance. If the size of the version store exceeds this threshold then any information that is only used for optional background tasks, such as reclaiming deleted space in the database, is instead sacrificed to preserve room for transactional information.
	PrereadIOMax	Gets or sets the maximum number of I/O operations dispatched for a given purpose.
	Recovery	Gets or sets a value indicating whether crash recovery is on.
	SystemDirectory	Gets or sets the relative or absolute file system path of the folder that will contain the checkpoint file for the instance.
	TempDirectory	Gets or sets the relative or absolute file system path of the folder that will contain the temporary database for the instance.
	VersionStoreTaskQueueMax	Gets or sets the number of background cleanup work items that can be queued to the database engine thread pool at any one time.
	WaypointLatency	Gets or sets the number of logs that esent will defer database flushes for. This can be used to increase database recoverability if failures cause logfiles to be lost. Supported on Windows 7 and up. Ignored on Windows XP, Windows Server 2003, Windows Vista and Windows Server 2008.

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Methods

	Name	Description
	Equals	(Inherited from Object.)
	Finalize	(Inherited from Object.)
	GetHashCode	(Inherited from Object.)
	GetType	(Inherited from Object.)
	MemberwiseClone	(Inherited from Object.)
	ToString	Returns a String that represents the current InstanceParameters. (Overrides Object.ToString().)

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See also

Reference

InstanceParameters class

Microsoft.Isam.Esent.Interop namespace