Because the index data stored in index segments is often much smaller than the record data contained in data segments of Vision 5 and Vision 6 files, a large pre-allocate or extension factor typically allocates many more blocks than are needed. V_INDEX_BLOCK_PERCENT allows you to determine the ratio of index block to data blocks that are created for a Vision file, which can help trim file size when disk space is tight.
The value range for V_INDEX_BLOCK_PERCENT is 1 to 1000, and the default value is 100.
For example, if you have a file with an extension factor of 10 and set V_INDEX_BLOCK_PERCENT to 50, the next time the file is extended, 10 new data blocks and 5 new index blocks are created. If you set V_INDEX_BLOCK_PERCENT to 200 for the same file, the next time the file is extended, 10 new data blocks and 20 new index blocks are created.