Mode 

Description 

fmManual 

The records are not fetched automatically by AnyDAC. A programmer must write code to fetch records at appropriate moments, using following methods:

• TADDataSet.FetchAll to fetch all records;
• TADDataSet.GetNextPacket to fetch next record set (packet), containing RowsetSize records;
• IADPhysCommand.Fetch to fetch all records or next record set;

 

fmOnDemand 

The records are fetched automatically by AnyDAC, when they are demanded by the navigation or other dataset methods. At each demand AnyDAC will fetch one or more record sets, containing RowsetSize records.
This mode allows to open big result set without a significant delay, like a fmAll mode. But total time of fetching of the all records will be more than in fmAll mode. For example, on Microsoft SQL Server will be used server side static cursor. 

fmAll 

All result set records are fetched automatically by AnyDAC at the dataset Open call or at the first IADPhysCommand.Fetch call.
On a big resultset it may take a time, but then navigation through a dataset will be fast, because all records will be stored in an AnyDAC internal data storage. For many DBMS's, like a Microsoft SQL Server, MySQL Server, Sybase SQL Anywhere:

• it releases client result set buffer and allows to execute next command returning resultsets;
• gives maximum fetch performance. For example, on Microsoft SQL Server will be used fast forward-only cursor.

 

fmExactRecsMax 

Similar to fmAll, but if the amount of the fetched records differs from specified in RecsMax, then exception is raised.