Overview

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The DBISAM ODBC Driver is contained within a single DLL with no external libraries required. It can be used with Visual Studio using the ODBCDirect access layer, and with Visual Studio .NET or higher with the ODBC.NET Data Provider.

The DBISAM ODBC Driver contains an easy-to-use configuration wizard for creating and modifying user and system data sources, and also supports direct driver connections using a connection string.

The complete source code for all utilities provided, and source code for DBISAM itself is available for an additional charge.

The utilities provided with DBISAM are:


Engine Features

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DBISAM can be used as a single-user, multi-user, or client-server engine.

DBISAM does not pre-allocate large blocks of memory and uses, by default, a very small 128k of memory for each physical table in a session that contains BLOB fields and 96k for each physical table in a session that does not contain BLOB fields - 32k for records, 64k for indexes, and 32k for BLOBs (if present). These figures can be adjusted in the engine to allow for more memory consumption, if so desired. It uses a LRU cache management algorithm that also includes intelligent read-ahead buffering, optimized, serialized writes, and support for read-only devices like CD-ROMs with optimized buffering.

Automatic record locking and manual table locking is provided in DBISAM. Record locking can be configured to be pessmistic (default) or optimistic.

DBISAM offers transaction support in the form of buffered, serialized transactions that allow tables to survive unexpected client workstation power-downs with little, or in most cases, no data corruption. They are not, however, completely fail-safe.

DBISAM includes automatic change detection with a change detection policy that can be configured as "lazy" or "strict" on a per-session basis. This allows you to specify how current data should be when it is accessed by the application.

The in-memory tables in DBISAM are identical to disk-based tables and can be shared among multiple threads in the same application. You can create and use both local in-memory tables, which are stored in the client application's memory, or remote in-memory tables, which are stored in the database server's memory. In-memory tables can be used in SQL and can be mixed with disk-based tables.
Table Format Features

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The default maximum file size in DBISAM is 128GB. DBISAM uses up to 3 physical files per logical table. All free space in DBISAM tables is automatically recycled. In addition, any free space can be removed from a table immediately by optimizing the table. DBISAM uses fixed-length record sizes and variable index page and BLOB block sizes. When creating or altering tables, some of the most useful feature include:






SQL Support

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DBISAM includes a subset of the SQL-92 standard, including a query optimizer, live and canned result sets, parameterized queries, scripts, and extended SQL syntax for DBISAM-specific features.
Client-Server Access

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DBISAM includes support for remote client-server access to a DBISAM database server. You can switch between local or multi-user usage and client-server usage with just a simple change to a connection string. Remote sessions include support for keep-alive pinging or the ability to maintain sessions that can survive connection interruptions, complete with dead session management for sessions that will never be reconnected due to a fatal client problem. Connection timeouts for remote sessions can be adjusted, and an event is fired whenever DBISAM is about to disconnect a remote session due to inactivity.

Remote sessions can be configured to use compression and strong encryption when accessing a DBISAM database server.
Administration

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DBISAM provides full local and remote administration capabilities. Databases can be backed up and restored manually or within scheduled events that automatically run at specified intervals. In fact, any administrative function can be run using a scheduled event.

DBISAM includes table creation and structure alteration, table verification and repair, table optimization, and import and export functionality. All of this functionality comes complete with progress, data conversion error, and log events to ensure that their execution can be customized and reported upon.