00679: How to access 4 Gigabyte Files with PRO/5 2.0

Title:

How to access 4 Gigabyte Files with PRO/5 2.0

Description:

Four Gigabyte MKEYED Files 
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By default, the MKEYED verb only creates 2GB files. PRO/5 2.0 has the capability to use 4GB MKEYED files on operating and file systems that can support 4GB files. See the PRO/5 readme file to see if your system supports this feature. 

LOCKMAX Adjustment 
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On 4GB files, the LOCKMAX value automatically adds 80000000 to either the default LOCKMAX value or to the value set in the config.bbx file. Do not set LOCKMAX to a value greater than 7fffffff, as adding 80000000 returns a negative value. 

Creating a New 4GB MKEYED File 
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Creating an MEKYED file with the SETOPTS Byte 7, Bit $80$ set automatically creates a 4GB file, provided that the operating system can support, and the file system is configured to support, 4GB files. 

Converting an MKEYED file from 2GB to 4GB 
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The following issues pertain to converting a 2GB file to a 4GB file: 

To instruct PRO/5 to convert an MKEYED file from 2GB to 4GB, include MODE=”4GB” in the OPEN statement. Performing this more than once slows down the OPEN process. 

If you use MODE=”4GB” in the OPEN statement a file that is already 4GB-enabled, PRO/5 will not return an error, but will take much longer to open the file. 

If you attempt to OPEN a 4GB file on systems that do not support 4GB files, the OPEN and conversion process will fail. No changes will be made to the state of the MKEYED file. 

Converting an MKEYED file from 4GB to 2GB 
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The following issues pertain to converting a 4GB file back to a 2GB file: 

You can only convert a 4GB file back to a 2GB file if the file size has not exceeded 2GB. 

To change the file back, OPEN the file and specify MODE=”2GB”. If the file size is over 2GB, opening the file will result in a failure of the OPEN and no conversion will take place. 

If a 4GB file ever exceeds 2GB, it cannot be converted back to 2GB using the MODE=””2GB” option. Deleting records to bring it under 2GB will not shrink the file. You can, however, create a new 2GB file, then copy the existing data into it. 

Additional Information 
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For clarification purposes, OPENing a file with MODE=”4GB” needs to be done ONE time on a file. Subsequent use of this mode will only slow the OPEN process down. 

However, Byte 7, bit $80$ needs to STAY turned on to provide 4 GB support.

Last Modified: 08/08/2003 Product: PRO/5 Operating System: N/A

BASIS structures five components of their technology into the BBx Generations.