Server Mode
- 3 minutes to read
The ExpressQuantumGrid control supports server mode – a fast, efficient data loading mode specially designed to work with large datasets (those with more than 50,000 records). This topic describes the grid features supported in this mode and their limitations. Click the links below to jump to the required section of this topic.
Server Mode Data Sources and Views
Features Supported in Server Mode
Server Mode Limitations
Server Mode Data Sources and Views
To enable the server mode for the grid control, you need to use the Server Mode Table View or Server Mode Banded Table View and bind it to a database table via a specially designed data source component linked to a FireDAC, dbExpress, or ADO connection (TFDConnection/TADConnection, TSQLConnection, or TADOConnection). Note that a data source component cannot be shared between Views – upon linking to a View, the data source component will be unlinked from the currently linked View automatically.
Server mode data source components include:
FireDac connection-based data sources: TdxServerModeFireDACDataSource and TdxServerModeFireDACQueryDataSource.
dbExpress connection-based data sources: TdxServerModeDBXDataSource and TdxServerModeDBXQueryDataSource.
ADO connection-based data sources: TdxServerModeADODataSource and TdxServerModeADOQueryDataSource.
The current server mode implementation provides support for Microsoft SQL Server, Microsoft Access, MySQL, Firebird, InterBase (see the note below), Oracle, Advantage, PostgreSQL, and SQLite databases. Refer to the Connecting to Data in Server Mode topic, to learn how to bind the ExpressQuantumGrid control to a database table in this mode.
Important
Query-based server mode data sources (TdxServerModeFireDACQueryDataSource, TdxServerModeDBXQueryDataSource, and TdxServerModeADOQueryDataSource) do not support InterBase databases.
Features Supported in Server Mode
The main data shaping and data representation features of the grid control supported in server mode are listed below.
In-place editors
Record management (adding and deleting records) (*)
Sorting data by group values and by group summaries (*)
Grouping data including date/time grouping options (*)
Filtering data including Filter Row and Find Panel capabilities (*). Refer to the corresponding section in this topic for details on the Find Panel‘s limitations
Calculating summaries (*)
(*) supported with limitations (see below)
Server Mode Limitations
In server mode, the View does not have simultaneous access to bound data in its entirety. This imposes some limitations on the View’s features and capabilities that are still available in regular bound mode. The list below includes the features that are not supported in server mode.
In-place editing and record management if the View is linked either to a query-based server mode data source or a table-based server mode data source connected to a database view
Master-detail relationships
Custom sorting and sorting by displayed values are not supported
The date/time grouping options are not supported for InterBase and SQLite databases
Providing additional data via unbound columns
The focused row’s position is not maintained when an end-user sorts against a column
The inserted row is not focused when the linked server mode data source is connected to a Microsoft Access, MySQL, InterBase, Oracle, SQLite, or Advantage database table
The number of selected rows may significantly hinder the performance of record management operations
Data group indexes are not maintained when updating the internal cache in response to group changes
Additionally, query-based server mode data source have the following restrictions on the SQL statement specified via the data source SQL property:
An expression in the SELECT list must always have a column alias. The DX0, DXRESULTSET, and DXROWNUMBER column aliases are reserved for internal use;
Row constraint functions or clauses are supported only if you provide the ORDER BY clause.