TCustomMSDataSet.FetchAll Property

Used to decrease the time of retrieving additional records to the client side when calling TMemDataSet.Locate and TMemDataSet.LocateEx for the first time.

Class

TCustomMSDataSet

Syntax

property FetchAll: boolean default True;

Remarks

When the FetchAll property is False, the first call to the TMemDataSet.Locate and TMemDataSet.LocateEx methods may take a lot of time to retrieve additional records to the client side. The default value is True.

Since SDAC 4.20, changing the value of the FetchAll option to True for a dataset open in the FetchAll=False mode will not lead to closing this dataset. This fill forces all records to be fetched to the client.

Note: When setting TCustomMSDataSet.FetchAll = False you should keep in mind that execution of such queries blocks the current session. In order to avoid blocking OLE DB creates additional session that causes the following problems:

• Each additional session runs outside the transaction context thus the TCustomDAConnection.Commit and TCustomDAConnection.Rollback operations in the main session won't apply changes made in additional sessions. This also concerns changes made by TDataSet.Post.
• No transactions can be started if there are underfetched datasets within the connection.
• Temporary tables created in one session are not accessible from other sessions therefore simultaneous using of FetchAll = False and temporary tables is impossible.
• When editing compound queries with ORDER BY clause setting FetchAll = False may lead to deadlock during TDataSet.Post.

Important: If there is more than one dataset attached to TMSConnection, setting FetchAll = False even in one of them may lead to the problems described above.

To prevent the TMSConnection object from creating additional connections for datasets that work in the FetchAll=False mode, you should enable the TMSConnectionOptions.MultipleActiveResultSets option. This option is supported since SQL Server 2005 with using SQL Native Client as OLE DB provider.

See Also

• Performance of Obtaining Data
• TMSConnectionOptions.MultipleActiveResultSets
• TMSConnectionOptions.Provider