Controls the way Sybase IQ determines whether to continue prefetching B-tree pages for a given query.
0 – 1000
2
Can be set for an individual connection or for the PUBLIC group. Takes effect immediately.
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 this option.
Experiment with different settings to find the one that gives the best performance. For most queries, useful settings are in the range of 1 to 10.
