To define Vision parameters and transaction processing options, select the Vision tab in the AcuODBC Configuration property sheet. You can also specify the map file for international characters. Complete the fields as indicated below.
Vision File Options
Max Files
This parameter is equivalent to the MAX_FILES variable in the runtime configuration file. It sets the maximum number of files that can be opened by AcuODBC. The default is "32". The maximum value is "256." Keeping this value small conserves memory.
Max Locks
This parameter is equivalent to the MAX_LOCKS variable in the runtime configuration file. It sets the maximum number of record locks that can be held by AcuODBC for all of the files together. The default matches the setting of "Max Files," in this case "32". The maximum value is "8191" for Vision files. Setting this variable to its maximum value can waste resources and is not recommended.
Locks Per File
This parameter is equivalent to the LOCKS_PER_FILE variable in the runtime configuration file. It sets the maximum number of record locks that can be held on a file when an SQL transaction has been issued by the Windows application. This value affects only the files that are maintaining multiple record locks. Typically, all read records for updating or deleting transaction data are locked. This field enables you to increase the number of locks per file so you can manage large transactions. The default setting is "10". The maximum value is "8191" for Vision files. Setting this variable to its maximum value can waste resources and is not recommended.
Buffers
This parameter is equivalent to the V_BUFFERS variable in the runtime configuration file. It lets you set the number of indexed block buffers to allocate. Each buffer is 512 bytes plus some overhead. These buffers are used to improve the performance of indexed files. The value can range from "0" (no buffering) to "256". The default is "32". Setting this number larger will generally improve file performance. Setting it smaller will save memory.
Transaction Support Options
Enable Transaction Processing Support
Select this check box to enable or disable transaction processing support in AcuODBC. If you are in a transaction processing environment, enable this feature to begin transaction management, locking, and other key functions. Selecting this check box activates the Enable Logging check box and the Temp File Directory field.
Enable Logging
Select/clear this check box to enable/disable transaction management logging and to activate the controls on this tab relating to logging. When this box is selected, file updates are logged to the transaction log file specified in the "Log File" field. By default, logging is off. This field is equivalent to the LOGGING configuration variable.
Encrypt Log File
Select this check box to encrypt records before writing them to the log file. By default, log encryption is off. This field is the equivalent to the LOG_ENCRYPTION configuration variable.
Log to Device
Selecting this box causes the transaction management system to assume that the log file is actually a device, rather than a file. This means that a special device locking method is on the log file. It also guarantees that the log file is opened "append" and that no seeks are performed on it. This allows for the use of a tape device for the log file on many systems. By default, this option is turned off. This field is equivalent to the LOG_DEVICE configuration variable.
Log File
Enter the name of the log file to be used for transaction management logging. (Activate transaction management logging by selecting the "Enable Logging" check box.) If the file does not exist, one is created. This field is equivalent to the LOG_FILE configuration variable.
You may store your transaction log file on a remote machine if your system utilizes AcuServer. To specify a remote filename for Log File, use remote name notation in this field. Note that AcuServer must be running on the remote machine.
Remote name notation has the following format:
@server-name:path-name/file-name
Log files prepended with @server-name:path-name are routed to AcuServer on the host specified by server-name, and stored in the directory specified by path-name.
Temp File Directory
This variable allows you to specify a directory to be used for holding the temporary files generated by the transaction management system. This field is equivalent to the TEMP_DIR configuration variable. If no directory is specified, temporary files are placed in the current directory.
Log Buffer Size
This sets the maximum buffer size, in bytes, for the transaction log file. It is equivalent to the LOG_BULLER_SIZE configuration variable. Acceptable values are from "0" to "32767". Log Buffer Size is examined before each write to the log file. Its default value is "512". If Log Buffer Size is set to "0", writes to the log file are synchronous (unbuffered). That is, if the log buffer size is "0", there is an operating system call after every write to the log buffer. If the number is large, there is a call only when the buffer is full. Acucorp recommends that you experiment to determine which size works best in your environment.