Question

Large datasets, millions of records, need special programming to maintain speed in DBGrids.

I want to know if there are any ready-made components for Delphi (DBGrids) that do this automatically?

EDIT For Example: Some databases have features such as fetch 1st X records (eg 100 records). When I reach the bottom with scrolling, I want to auto fetch the next 100. Conversely when I reach the beginning, I want to fetch the previous 100. I know I can program this, but it sure is possible to propagate that feature to a DBGrid control where the DBGrid does the buffering. It will save quite a bit of programming – you simply have to set the ‘buffer size’ so to speak.

Answer 1

I would have a look at Developer Express QuantumGrid Suite. (@birger: you just were a tick faster 😉 ) So I’m not just duplicating the answer, some elaboration:

The DevExpress Grid uses a data controller that has several modes to controll the data bound to the grid. One of these is exactly what you are looking for:

Grid Mode

When using Grid Mode, only a fixed number of dataset records is loaded into memory. Because only a limited set of records are retrieved from the dataset, automatic sorting, filtering and summary calculations are disabled in Grid Mode (must be controlled manually instead). By default, this mode is disabled and the ExpressDataController loads all records in a dataset.

It does have some drawbacks, which seem pretty obvious: you cannot make a summary, sort, or filter if you do not have all records at hand.