Set the PREFETCH_BUFFER_LIMIT and BT_PREFETCH_MAX_MISS options to control prefetch memory behavior.
The PREFETCH_BUFFER_LIMIT option defines the number of cache pages available to Sybase IQ for use in prefetching (the read ahead of database pages). This option has a default value of 0. Set this option only if advised to do so by Sybase Technical Support.
The BT_PREFETCH_MAX_MISS option determines whether to continue prefetching pages for a given query. If queries using HG indexes run more slowly than expected, try gradually increasing the value of this option.