00001 /* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*- 00002 * vim:expandtab:shiftwidth=2:tabstop=2:smarttab: 00003 * 00004 * Copyright (C) 2008-2009 Sun Microsystems, Inc. 00005 * 00006 * This program is free software; you can redistribute it and/or modify 00007 * it under the terms of the GNU General Public License as published by 00008 * the Free Software Foundation; version 2 of the License. 00009 * 00010 * This program is distributed in the hope that it will be useful, 00011 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00013 * GNU General Public License for more details. 00014 * 00015 * You should have received a copy of the GNU General Public License 00016 * along with this program; if not, write to the Free Software 00017 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 00018 */ 00019 00020 #pragma once 00021 00022 #include <drizzled/memory/sql_alloc.h> 00023 00024 namespace drizzled 00025 { 00026 00027 namespace optimizer 00028 { 00029 00030 class RangeParameter; 00031 class SEL_TREE; 00032 class SEL_ARG; 00033 00034 /* 00035 SEL_IMERGE is a list of possible ways to do index merge, i.e. it is 00036 a condition in the following form: 00037 (t_1||t_2||...||t_N) && (next) 00038 00039 where all t_i are optimizer::SEL_TREEs, next is another SEL_IMERGE and no pair 00040 (t_i,t_j) contains SEL_ARGS for the same index. 00041 00042 optimizer::SEL_TREE contained in SEL_IMERGE always has merges=NULL. 00043 00044 This class relies on memory manager to do the cleanup. 00045 */ 00046 class SEL_IMERGE : public memory::SqlAlloc 00047 { 00048 enum { PREALLOCED_TREES= 10}; 00049 public: 00050 SEL_TREE *trees_prealloced[PREALLOCED_TREES]; 00051 SEL_TREE **trees; /* trees used to do index_merge */ 00052 SEL_TREE **trees_next; /* last of these trees */ 00053 SEL_TREE **trees_end; /* end of allocated space */ 00054 00055 SEL_ARG ***best_keys; /* best keys to read in optimizer::SEL_TREEs */ 00056 00057 SEL_IMERGE(); 00058 00059 /* 00060 Add optimizer::SEL_TREE to this index_merge without any checks, 00061 00062 NOTES 00063 This function implements the following: 00064 (x_1||...||x_N) || t = (x_1||...||x_N||t), where x_i, t are optimizer::SEL_TREEs 00065 00066 RETURN 00067 0 - OK 00068 -1 - Out of memory. 00069 */ 00070 int or_sel_tree(RangeParameter *param, SEL_TREE *tree); 00071 00072 /* 00073 Perform OR operation on this SEL_IMERGE and supplied optimizer::SEL_TREE new_tree, 00074 combining new_tree with one of the trees in this SEL_IMERGE if they both 00075 have SEL_ARGs for the same key. 00076 00077 SYNOPSIS 00078 or_sel_tree_with_checks() 00079 param Parameter from SqlSelect::test_quick_select 00080 new_tree optimizer::SEL_TREE with type KEY or KEY_SMALLER. 00081 00082 NOTES 00083 This does the following: 00084 (t_1||...||t_k)||new_tree = 00085 either 00086 = (t_1||...||t_k||new_tree) 00087 or 00088 = (t_1||....||(t_j|| new_tree)||...||t_k), 00089 00090 where t_i, y are optimizer::SEL_TREEs. 00091 new_tree is combined with the first t_j it has a SEL_ARG on common 00092 key with. As a consequence of this, choice of keys to do index_merge 00093 read may depend on the order of conditions in WHERE part of the query. 00094 00095 RETURN 00096 0 OK 00097 1 One of the trees was combined with new_tree to optimizer::SEL_TREE::ALWAYS, 00098 and (*this) should be discarded. 00099 -1 An error occurred. 00100 */ 00101 int or_sel_tree_with_checks(optimizer::RangeParameter *param, optimizer::SEL_TREE *new_tree); 00102 00103 /* 00104 Perform OR operation on this index_merge and supplied index_merge list. 00105 00106 RETURN 00107 0 - OK 00108 1 - One of conditions in result is always true and this SEL_IMERGE 00109 should be discarded. 00110 -1 - An error occurred 00111 */ 00112 int or_sel_imerge_with_checks(optimizer::RangeParameter *param, SEL_IMERGE* imerge); 00113 00114 }; 00115 00116 00117 } /* namespace optimizer */ 00118 00119 } /* namespace drizzled */ 00120