Use Speed Sort (-TB) primarily to improve sort performance.

Operating system and syntax UNIX / Windows -TB blocksize
Use with Maximum value Minimum value Single-user default Multi-user default
Client Session    31 1 8 8
blocksize
The block size in kilobytes, to allocate when sorting records for reports. The default block size is 8K but can be reset anywhere from 1KB to 31KB.

If you increase the block size beyond 8KB, OpenEdge sorts records faster but uses more memory and disk space in the process. If system memory is severely limited, you might actually choose to lower the block size.

Sort space is allocated in the SRT file, a temporary session file having a system-generated unique name with the prefix srt. OpenEdge uses the SRT file to store session-compile modules and as temporary work space during sorting (including rebuilding indexes). Use -TB to set the SRT file block size (that is, the increments by which the SRT file grows).

In summary, increase -TB to at least 8 to improve index rebuild operations by 15 percent or more. Or, decrease -TB to 1 to relieve severe Windows memory shortages during sort operations.

See also the Merge Number (-TM) and Maximum Memory (-mmax) startup parameters.