Controls the way Sybase IQ determines whether to continue prefetching B-tree pages for a given query.
Use only if instructed to do so by Sybase Technical Support. For queries that use HG (High_Group) indexes, Sybase IQ prefetches B-tree pages sequentially until it determines that prefetching is no longer useful. For some queries, it might turn off prefetching prematurely. Increasing the value of BT_PREFETCH_MAX_MISS makes it more likely that Sybase IQ continues prefetching, but also might increase I/O unnecessarily.
If queries using HG indexes run more slowly than expected, try gradually increasing the value of BT_PREFETCH_MAX_MISS.
Experiment with different settings to find the setting that gives the best performance. For most queries, useful settings are in the range of 1 to 10.