page = (BtPage)((uid)slot * bt->page_size + bt->pagepool);
#ifdef unix
posix_fadvise (bt->idx, page_no << bt->page_bits, bt->page_size, POSIX_FADV_WILLNEED);
page = (BtPage)((uid)slot * bt->page_size + bt->pagepool);
#ifdef unix
posix_fadvise (bt->idx, page_no << bt->page_bits, bt->page_size, POSIX_FADV_WILLNEED);