Hi,
On Windows 7 64-bit I am reading data from a large dBase .DBF file that includes an .MDX index file through ODBC/ADO. When the table is on a read/write location performance is good, but when it is stored at a read-only location performance drops radically. From the process monitor (by SysInternals) I can tell that the .MDX index file is not used when I am reading the read-only .DBF file, where it is used correcly when read from the read/write location.
In read-only mode I can see that the driver first tries to open the DBF file with read/write access, resulting in "ACCESS DENIED". Next, the entire table (around 800 MB) is read as can be seen from the task manager. In read/write mode this is not
the case.
The connection strings I used are:
DRIVER={Microsoft Access dBASE Driver (*.dbf, *.ndx, *.mdx)}; DBQ=C:\somedir; DriverID=277;
and
Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\somedir;Extended Properties=dBase IV;'
The driver was obtained by installing the "Microsoft Access Database Engine 2010 Redistributable" (AccessDatabaseEngine_x64.exe) from http://www.microsoft.com/en-us/download/details.aspx?id=13255.
Any help on this problem is appreciated. I was unable to find existing forum posts related to this problem.
Regards,
Lennert.