CacheStart Property
Applies To
Dynaset-Type Recordset object, Recordset object.
Description
Sets or returns a value that specifies the bookmark of the first record in a dynaset-type Recordset object containing data to be locally cached from an ODBC data source (Microsoft Jet workspaces only).
Settings And Return Values
The setting or return value is a String that specifies a bookmark.
Remarks
Data caching improves the performance of an application that retrieves data from a remote server through dynaset-type Recordset objects. A cache is a space in local memory that holds the data most recently retrieved from the server in the event that the data will be requested again while the application is running. When data is requested, the Microsoft Jet database engine checks the cache for the requested data first rather than retrieving it from the server, which takes more time. Only data from an ODBC data source can be saved in the cache.
Any Microsoft Jet-connected ODBC data source, such as a linked table, can have a local cache. To create the cache, open a Recordset object from the remote data source, set the CacheSize and CacheStart properties, and then use the FillCache method or step through the records using the Move methods.
The CacheStart property setting is the bookmark of the first record in the Recordset object to be cached. You can use the bookmark of any record to set the CacheStart property. Make the record you want to start the cache the current record, and set the CacheStart property equal to the Bookmark property.
The Microsoft Jet database engine requests records within the cache range from the cache, and it requests records outside the cache range from the server.
Records retrieved from the cache don't reflect changes made concurrently to the source data by other users.
To force an update of all the cached data, set the CacheSize property of the Recordset object to 0, set it to the size of the cache you originally requested, and then use the FillCache method.
See Also
CacheSize property.
Specifics (Microsoft Access)
When you use the CacheStart property in a Microsoft Access module, you must include an Option Compare Binary statement in the Declarations section of the module. The bookmark set or returned by the CacheStart property is a Variant array of Byte data, so the string comparison method for the module must be binary. If a bookmark is evaluated with a text-based string comparison method, such as the Option Compare Text statement or the default setting for the Option Compare Database statement, the current record may be set to an incorrect record.