/* Copyright (C) 2000 MySQL AB & Alexey Botchkov & MySQL Finland AB & TCX DataKonsult AB This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #include "myisamdef.h" #include "rt_index.h" #include "rt_key.h" #include "rt_mbr.h" typedef struct { double square; int n_node; uchar *key; double *coords; } SplitStruct; inline static double *reserve_coords(double **d_buffer, int n_dim) { double *coords = *d_buffer; (*d_buffer) += n_dim * 2; return coords; } static void mbr_join(double *a, const double *b, int n_dim) { double *end = a + n_dim * 2; do { if (a[0] > b[0]) a[0] = b[0]; if (a[1] < b[1]) a[1] = b[1]; a += 2; b += 2; }while (a != end); } /* Counts the square of mbr which is a join of a and b */ static double mbr_join_square(const double *a, const double *b, int n_dim) { const double *end = a + n_dim * 2; double square = 1.0; do { square *= ((a[1] < b[1]) ? b[1] : a[1]) - ((a[0] > b[0]) ? b[0] : a[0]); a += 2; b += 2; }while (a != end); return square; } static double count_square(const double *a, int n_dim) { const double *end = a + n_dim * 2; double square = 1.0; do { square *= a[1] - a[0]; a += 2; }while (a != end); return square; } inline static void copy_coords(double *dst, const double *src, int n_dim) { memcpy(dst, src, sizeof(double) * (n_dim * 2)); } /* Select two nodes to collect group upon */ static void pick_seeds(SplitStruct *node, int n_entries, SplitStruct **seed_a, SplitStruct **seed_b, int n_dim) { SplitStruct *cur1; SplitStruct *lim1 = node + (n_entries - 1); SplitStruct *cur2; SplitStruct *lim2 = node + n_entries; double max_d = -DBL_MAX; double d; for (cur1 = node; cur1 < lim1; ++cur1) { for (cur2=cur1 + 1; cur2 < lim2; ++cur2) { d = mbr_join_square(cur1->coords, cur2->coords, n_dim) - cur1->square - cur2->square; if (d > max_d) { max_d = d; *seed_a = cur1; *seed_b = cur2; } } } } /* Select next node and group where to add */ static void pick_next(SplitStruct *node, int n_entries, double *g1, double *g2, SplitStruct **choice, int *n_group, int n_dim) { SplitStruct *cur = node; SplitStruct *end = node + n_entries; double max_diff = -DBL_MAX; for (; cur<end; ++cur) { double diff; double abs_diff; if (cur->n_node) { continue; } diff = mbr_join_square(g1, cur->coords, n_dim) - mbr_join_square(g2, cur->coords, n_dim); abs_diff = fabs(diff); if (abs_diff > max_diff) { max_diff = abs_diff; *n_group = 1 + (diff > 0); *choice = cur; } } } /* Mark not-in-group entries as n_group */ static void mark_all_entries(SplitStruct *node, int n_entries, int n_group) { SplitStruct *cur = node; SplitStruct *end = node + n_entries; for (; cur<end; ++cur) { if (cur->n_node) { continue; } cur->n_node = n_group; } } static int split_rtree_node(SplitStruct *node, int n_entries, int all_size, /* Total key's size */ int key_size, int min_size, /* Minimal group size */ int size1, int size2 /* initial group sizes */, double **d_buffer, int n_dim) { SplitStruct *cur; SplitStruct *a; SplitStruct *b; double *g1 = reserve_coords(d_buffer, n_dim); double *g2 = reserve_coords(d_buffer, n_dim); SplitStruct *next; int next_node; int i; SplitStruct *end = node + n_entries; if (all_size < min_size * 2) { return 1; } cur = node; for (; cur<end; ++cur) { cur->square = count_square(cur->coords, n_dim); cur->n_node = 0; } pick_seeds(node, n_entries, &a, &b, n_dim); a->n_node = 1; b->n_node = 2; copy_coords(g1, a->coords, n_dim); size1 += key_size; copy_coords(g2, b->coords, n_dim); size2 += key_size; for (i=n_entries - 2; i>0; --i) { if (all_size - (size2 + key_size) < min_size) /* Can't write into group 2 */ { mark_all_entries(node, n_entries, 1); break; } if (all_size - (size1 + key_size) < min_size) /* Can't write into group 1 */ { mark_all_entries(node, n_entries, 2); break; } pick_next(node, n_entries, g1, g2, &next, &next_node, n_dim); if (next_node == 1) { size1 += key_size; mbr_join(g1, next->coords, n_dim); } else { size2 += key_size; mbr_join(g2, next->coords, n_dim); } next->n_node = next_node; } return 0; } int rtree_split_page(MI_INFO *info, MI_KEYDEF *keyinfo, uchar *page, uchar *key, uint key_length, my_off_t *new_page_offs) { int n1, n2; /* Number of items in groups */ SplitStruct *task; SplitStruct *cur; SplitStruct *stop; double *coord_buf; double *next_coord; double *old_coord; int n_dim; uchar *source_cur, *cur1, *cur2; uchar *new_page; int err_code = 0; uint nod_flag = mi_test_if_nod(page); uint full_length = key_length + (nod_flag ? nod_flag : info->s->base.rec_reflength); int max_keys = (mi_getint(page)-2) / (full_length); n_dim = (keyinfo->keysegs-1) / 2; { int coord_buf_size = n_dim * 2 * sizeof(double) * (max_keys + 1 + 4); coord_buf = my_alloca(coord_buf_size + sizeof(SplitStruct) * (max_keys + 1)); task = (SplitStruct *)(((char *)coord_buf) + coord_buf_size); } next_coord = coord_buf; stop = task + max_keys; source_cur = rt_PAGE_FIRST_KEY(page, nod_flag); for (cur = task; cur < stop; ++cur, source_cur = rt_PAGE_NEXT_KEY(source_cur, key_length, nod_flag)) { cur->coords = reserve_coords(&next_coord, n_dim); cur->key = source_cur; rtree_d_mbr(keyinfo->seg, source_cur, key_length, cur->coords); } cur->coords = reserve_coords(&next_coord, n_dim); rtree_d_mbr(keyinfo->seg, key, key_length, cur->coords); cur->key = key; old_coord = next_coord; if (split_rtree_node(task, max_keys + 1, mi_getint(page) + full_length + 2, full_length, rt_PAGE_MIN_SIZE(keyinfo->block_length), 2, 2, &next_coord, n_dim)) { err_code = 1; goto split_err; } if (!(new_page = (uchar*)my_alloca((uint)keyinfo->block_length))) return -1; stop = task + (max_keys + 1); cur1 = rt_PAGE_FIRST_KEY(page, nod_flag); cur2 = rt_PAGE_FIRST_KEY(new_page, nod_flag); n1 = 0; n2 = 0; for (cur = task; cur < stop; ++cur) { uchar *to; if (cur->n_node == 1) { to = cur1; cur1 = rt_PAGE_NEXT_KEY(cur1, key_length, nod_flag); ++n1; } else { to = cur2; cur2 = rt_PAGE_NEXT_KEY(cur2, key_length, nod_flag); ++n2; } memcpy(to - nod_flag, cur->key - nod_flag, full_length); } mi_putint(page, 2 + n1 * full_length, nod_flag); mi_putint(new_page, 2 + n2 * full_length, nod_flag); *new_page_offs=_mi_new(info, keyinfo); _mi_write_keypage(info, keyinfo, *new_page_offs, new_page); my_afree((byte*)new_page); split_err: my_afree((byte*)coord_buf); return err_code; }