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SQL Anywhere 10.0.1 » UltraLite - .NET Programming » UltraLite .NET 1.0 API Reference » ULConnectionParms class

ULConnectionParms constructor Next Page

AdditionalParms property


Specifies additional parameters as a semicolon-separated list of name=value pairs. These are less commonly used parameters.

Syntax

Visual Basic

Public Property AdditionalParms As String

C#

public string AdditionalParms {get;set;}

Property value

A semicolon-separated list of keyword=value additional parameters. Values of the keyword=value list must conform to the rules for ULConnection.ConnectionString. The default is a null reference (Nothing in Visual Basic).

Remarks

The values for the page size and reserve size parameters are specified in units of bytes. Use the suffix k or K to indicate units of kilobytes and the suffix m or M to indicate megabytes.

Additional parameters are:

Keyword

Description

dbn

Identifies a loaded database to which a connection needs to be made.

When a database is started, it is assigned a database name, either explicitly with the dbn parameter, or by UltraLite using the base of the file name with the extension and path removed.

When opening connections, UltraLite first searches for a running database with a matching dbn. If one is not found, UltraLite starts a new database using the appropriate database file name parameter (DatabaseOnCE or DatabaseOnDesktop).

This parameter is required if the application (or UltraLite engine) needs to access two different databases that have the same base file name.

This parameter is only used when opening a connection with ULConnection.Open.

ordered_table_scans

Specifies whether SQL queries without ORDER BY clauses should perform ordered table scans by default.

As of release 10.0.1, when using dynamic SQL in UltraLite, if order is not important for executing a query, UltraLite will access the rows directly from the database pages rather than using the primary key index. This improves performance of fetching rows. To use this optimization, the query must be read only and must scan all the rows.

When rows are expected in a specific order, an ORDER BY statement should be included as part of the SQL query. However, it's possible that some applications have come to rely on the behavior that defaults to returning rows in the primary key order. In this case, users should set the ordered_table_scans parameter to 1 (true, yes, on) to revert to the old behavior when iterating over a table.

When ordered_table_scans is set to 1 (true, yes, on) and the user does not specify an ORDER BY clause or if a query would not benefit from an index, UltraLite will default to using the primary key.

The following parameter string ensures that UltraLite behaves as in previous releases.

createParms.AdditionalParms = "ordered_table_scans=yes"

The default is 0 (false, off, no).

This parameter is only used when opening a connection with ULConnection.Open.

For more information, see UltraLite Connection String Parameters Reference.

reserve_size

Reserves file system space for storage of UltraLite persistent data.

The reserve_size parameter allows you to pre-allocate the file system space required for your UltraLite database without inserting any data. Reserving file system space can improve performance slightly and also prevent out of memory failures. By default, the persistent storage file only grows when required as the application updates the database.

Note that reserve_size reserves file system space, which includes the metadata in the persistent store file, and not just the raw data. The metadata overhead, as well as data compression, must be considered when deriving the required file system space from the amount of database data. Running the database with test data and observing the persistent store file size is recommended.

The reserve_size parameter reserves space by growing the persistent store file to the given reserve size on startup, regardless of whether the file previously existed. The file is never truncated.

The following parameter string ensures that the persistent store file is at least 2 MB upon startup.

createParms.AdditionalParms = "reserve_size=2m"

This parameter is only used when opening a connection with ULConnection.Open.

start

Specifies the location and then starts the UltraLite engine.

Only supply a StartLine (START) connection parameter if you are connecting to an engine that is not currently running.

The location is only required when the UltraLite engine is not in the system path.

For more information on using the UltraLite engine with UltraLite.NET, see the RuntimeType property.

Exceptions
See also