/***************************************************************************** Copyright (c) 1997, 2009, Innobase Oy. All Rights Reserved. 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; version 2 of the License. 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 *****************************************************************************/ /**************************************************//** @file pars/pars0opt.c Simple SQL optimizer Created 12/21/1997 Heikki Tuuri *******************************************************/ #include "pars0opt.h" #ifdef UNIV_NONINL #include "pars0opt.ic" #endif #include "row0sel.h" #include "row0ins.h" #include "row0upd.h" #include "dict0dict.h" #include "dict0mem.h" #include "que0que.h" #include "pars0grm.h" #include "pars0pars.h" #include "lock0lock.h" #define OPT_EQUAL 1 /* comparison by = */ #define OPT_COMPARISON 2 /* comparison by <, >, <=, or >= */ #define OPT_NOT_COND 1 #define OPT_END_COND 2 #define OPT_TEST_COND 3 #define OPT_SCROLL_COND 4 /*******************************************************************//** Inverts a comparison operator. @return the equivalent operator when the order of the arguments is switched */ static int opt_invert_cmp_op( /*==============*/ int op) /*!< in: operator */ { if (op == '<') { return('>'); } else if (op == '>') { return('<'); } else if (op == '=') { return('='); } else if (op == PARS_LE_TOKEN) { return(PARS_GE_TOKEN); } else if (op == PARS_GE_TOKEN) { return(PARS_LE_TOKEN); } else { ut_error; } return(0); } /*******************************************************************//** Checks if the value of an expression can be calculated BEFORE the nth table in a join is accessed. If this is the case, it can possibly be used in an index search for the nth table. @return TRUE if already determined */ static ibool opt_check_exp_determined_before( /*============================*/ que_node_t* exp, /*!< in: expression */ sel_node_t* sel_node, /*!< in: select node */ ulint nth_table) /*!< in: nth table will be accessed */ { func_node_t* func_node; sym_node_t* sym_node; dict_table_t* table; que_node_t* arg; ulint i; ut_ad(exp && sel_node); if (que_node_get_type(exp) == QUE_NODE_FUNC) { func_node = exp; arg = func_node->args; while (arg) { if (!opt_check_exp_determined_before(arg, sel_node, nth_table)) { return(FALSE); } arg = que_node_get_next(arg); } return(TRUE); } ut_a(que_node_get_type(exp) == QUE_NODE_SYMBOL); sym_node = exp; if (sym_node->token_type != SYM_COLUMN) { return(TRUE); } for (i = 0; i < nth_table; i++) { table = sel_node_get_nth_plan(sel_node, i)->table; if (sym_node->table == table) { return(TRUE); } } return(FALSE); } /*******************************************************************//** Looks in a comparison condition if a column value is already restricted by it BEFORE the nth table is accessed. @return expression restricting the value of the column, or NULL if not known */ static que_node_t* opt_look_for_col_in_comparison_before( /*==================================*/ ulint cmp_type, /*!< in: OPT_EQUAL, OPT_COMPARISON */ ulint col_no, /*!< in: column number */ func_node_t* search_cond, /*!< in: comparison condition */ sel_node_t* sel_node, /*!< in: select node */ ulint nth_table, /*!< in: nth table in a join (a query from a single table is considered a join of 1 table) */ ulint* op) /*!< out: comparison operator ('=', PARS_GE_TOKEN, ... ); this is inverted if the column appears on the right side */ { sym_node_t* sym_node; dict_table_t* table; que_node_t* exp; que_node_t* arg; ut_ad(search_cond); ut_a((search_cond->func == '<') || (search_cond->func == '>') || (search_cond->func == '=') || (search_cond->func == PARS_GE_TOKEN) || (search_cond->func == PARS_LE_TOKEN)); table = sel_node_get_nth_plan(sel_node, nth_table)->table; if ((cmp_type == OPT_EQUAL) && (search_cond->func != '=')) { return(NULL); } else if ((cmp_type == OPT_COMPARISON) && (search_cond->func != '<') && (search_cond->func != '>') && (search_cond->func != PARS_GE_TOKEN) && (search_cond->func != PARS_LE_TOKEN)) { return(NULL); } arg = search_cond->args; if (que_node_get_type(arg) == QUE_NODE_SYMBOL) { sym_node = arg; if ((sym_node->token_type == SYM_COLUMN) && (sym_node->table == table) && (sym_node->col_no == col_no)) { /* sym_node contains the desired column id */ /* Check if the expression on the right side of the operator is already determined */ exp = que_node_get_next(arg); if (opt_check_exp_determined_before(exp, sel_node, nth_table)) { *op = search_cond->func; return(exp); } } } exp = search_cond->args; arg = que_node_get_next(arg); if (que_node_get_type(arg) == QUE_NODE_SYMBOL) { sym_node = arg; if ((sym_node->token_type == SYM_COLUMN) && (sym_node->table == table) && (sym_node->col_no == col_no)) { if (opt_check_exp_determined_before(exp, sel_node, nth_table)) { *op = opt_invert_cmp_op(search_cond->func); return(exp); } } } return(NULL); } /*******************************************************************//** Looks in a search condition if a column value is already restricted by the search condition BEFORE the nth table is accessed. Takes into account that if we will fetch in an ascending order, we cannot utilize an upper limit for a column value; in a descending order, respectively, a lower limit. @return expression restricting the value of the column, or NULL if not known */ static que_node_t* opt_look_for_col_in_cond_before( /*============================*/ ulint cmp_type, /*!< in: OPT_EQUAL, OPT_COMPARISON */ ulint col_no, /*!< in: column number */ func_node_t* search_cond, /*!< in: search condition or NULL */ sel_node_t* sel_node, /*!< in: select node */ ulint nth_table, /*!< in: nth table in a join (a query from a single table is considered a join of 1 table) */ ulint* op) /*!< out: comparison operator ('=', PARS_GE_TOKEN, ... ) */ { func_node_t* new_cond; que_node_t* exp; if (search_cond == NULL) { return(NULL); } ut_a(que_node_get_type(search_cond) == QUE_NODE_FUNC); ut_a(search_cond->func != PARS_OR_TOKEN); ut_a(search_cond->func != PARS_NOT_TOKEN); if (search_cond->func == PARS_AND_TOKEN) { new_cond = search_cond->args; exp = opt_look_for_col_in_cond_before(cmp_type, col_no, new_cond, sel_node, nth_table, op); if (exp) { return(exp); } new_cond = que_node_get_next(new_cond); exp = opt_look_for_col_in_cond_before(cmp_type, col_no, new_cond, sel_node, nth_table, op); return(exp); } exp = opt_look_for_col_in_comparison_before(cmp_type, col_no, search_cond, sel_node, nth_table, op); if (exp == NULL) { return(NULL); } /* If we will fetch in an ascending order, we cannot utilize an upper limit for a column value; in a descending order, respectively, a lower limit */ if (sel_node->asc && ((*op == '<') || (*op == PARS_LE_TOKEN))) { return(NULL); } else if (!sel_node->asc && ((*op == '>') || (*op == PARS_GE_TOKEN))) { return(NULL); } return(exp); } /*******************************************************************//** Calculates the goodness for an index according to a select node. The goodness is 4 times the number of first fields in index whose values we already know exactly in the query. If we have a comparison condition for an additional field, 2 point are added. If the index is unique, and we know all the unique fields for the index we add 1024 points. For a clustered index we add 1 point. @return goodness */ static ulint opt_calc_index_goodness( /*====================*/ dict_index_t* index, /*!< in: index */ sel_node_t* sel_node, /*!< in: parsed select node */ ulint nth_table, /*!< in: nth table in a join */ que_node_t** index_plan, /*!< in/out: comparison expressions for this index */ ulint* last_op) /*!< out: last comparison operator, if goodness > 1 */ { que_node_t* exp; ulint goodness; ulint n_fields; ulint col_no; ulint op; ulint j; goodness = 0; /* Note that as higher level node pointers in the B-tree contain page addresses as the last field, we must not put more fields in the search tuple than dict_index_get_n_unique_in_tree(index); see the note in btr_cur_search_to_nth_level. */ n_fields = dict_index_get_n_unique_in_tree(index); for (j = 0; j < n_fields; j++) { col_no = dict_index_get_nth_col_no(index, j); exp = opt_look_for_col_in_cond_before( OPT_EQUAL, col_no, sel_node->search_cond, sel_node, nth_table, &op); if (exp) { /* The value for this column is exactly known already at this stage of the join */ index_plan[j] = exp; *last_op = op; goodness += 4; } else { /* Look for non-equality comparisons */ exp = opt_look_for_col_in_cond_before( OPT_COMPARISON, col_no, sel_node->search_cond, sel_node, nth_table, &op); if (exp) { index_plan[j] = exp; *last_op = op; goodness += 2; } break; } } if (goodness >= 4 * dict_index_get_n_unique(index)) { goodness += 1024; if (dict_index_is_clust(index)) { goodness += 1024; } } /* We have to test for goodness here, as last_op may note be set */ if (goodness && dict_index_is_clust(index)) { goodness++; } return(goodness); } /*******************************************************************//** Calculates the number of matched fields based on an index goodness. @return number of excatly or partially matched fields */ UNIV_INLINE ulint opt_calc_n_fields_from_goodness( /*============================*/ ulint goodness) /*!< in: goodness */ { return(((goodness % 1024) + 2) / 4); } /*******************************************************************//** Converts a comparison operator to the corresponding search mode PAGE_CUR_GE, ... @return search mode */ UNIV_INLINE ulint opt_op_to_search_mode( /*==================*/ ibool asc, /*!< in: TRUE if the rows should be fetched in an ascending order */ ulint op) /*!< in: operator '=', PARS_GE_TOKEN, ... */ { if (op == '=') { if (asc) { return(PAGE_CUR_GE); } else { return(PAGE_CUR_LE); } } else if (op == '<') { ut_a(!asc); return(PAGE_CUR_L); } else if (op == '>') { ut_a(asc); return(PAGE_CUR_G); } else if (op == PARS_GE_TOKEN) { ut_a(asc); return(PAGE_CUR_GE); } else if (op == PARS_LE_TOKEN) { ut_a(!asc); return(PAGE_CUR_LE); } else { ut_error; } return(0); } /*******************************************************************//** Determines if a node is an argument node of a function node. @return TRUE if is an argument */ static ibool opt_is_arg( /*=======*/ que_node_t* arg_node, /*!< in: possible argument node */ func_node_t* func_node) /*!< in: function node */ { que_node_t* arg; arg = func_node->args; while (arg) { if (arg == arg_node) { return(TRUE); } arg = que_node_get_next(arg); } return(FALSE); } /*******************************************************************//** Decides if the fetching of rows should be made in a descending order, and also checks that the chosen query plan produces a result which satisfies the order-by. */ static void opt_check_order_by( /*===============*/ sel_node_t* sel_node) /*!< in: select node; asserts an error if the plan does not agree with the order-by */ { order_node_t* order_node; dict_table_t* order_table; ulint order_col_no; plan_t* plan; ulint i; if (!sel_node->order_by) { return; } order_node = sel_node->order_by; order_col_no = order_node->column->col_no; order_table = order_node->column->table; /* If there is an order-by clause, the first non-exactly matched field in the index used for the last table in the table list should be the column defined in the order-by clause, and for all the other tables we should get only at most a single row, otherwise we cannot presently calculate the order-by, as we have no sort utility */ for (i = 0; i < sel_node->n_tables; i++) { plan = sel_node_get_nth_plan(sel_node, i); if (i < sel_node->n_tables - 1) { ut_a(dict_index_get_n_unique(plan->index) <= plan->n_exact_match); } else { ut_a(plan->table == order_table); ut_a((dict_index_get_n_unique(plan->index) <= plan->n_exact_match) || (dict_index_get_nth_col_no(plan->index, plan->n_exact_match) == order_col_no)); } } } /*******************************************************************//** Optimizes a select. Decides which indexes to tables to use. The tables are accessed in the order that they were written to the FROM part in the select statement. */ static void opt_search_plan_for_table( /*======================*/ sel_node_t* sel_node, /*!< in: parsed select node */ ulint i, /*!< in: this is the ith table */ dict_table_t* table) /*!< in: table */ { plan_t* plan; dict_index_t* index; dict_index_t* best_index; ulint n_fields; ulint goodness; ulint last_op = 75946965; /* Eliminate a Purify warning */ ulint best_goodness; ulint best_last_op = 0; /* remove warning */ que_node_t* index_plan[256]; que_node_t* best_index_plan[256]; plan = sel_node_get_nth_plan(sel_node, i); plan->table = table; plan->asc = sel_node->asc; plan->pcur_is_open = FALSE; plan->cursor_at_end = FALSE; /* Calculate goodness for each index of the table */ index = dict_table_get_first_index(table); best_index = index; /* Eliminate compiler warning */ best_goodness = 0; /* should be do ... until ? comment by Jani */ while (index) { goodness = opt_calc_index_goodness(index, sel_node, i, index_plan, &last_op); if (goodness > best_goodness) { best_index = index; best_goodness = goodness; n_fields = opt_calc_n_fields_from_goodness(goodness); ut_memcpy(best_index_plan, index_plan, n_fields * sizeof(void*)); best_last_op = last_op; } index = dict_table_get_next_index(index); } plan->index = best_index; n_fields = opt_calc_n_fields_from_goodness(best_goodness); if (n_fields == 0) { plan->tuple = NULL; plan->n_exact_match = 0; } else { plan->tuple = dtuple_create(pars_sym_tab_global->heap, n_fields); dict_index_copy_types(plan->tuple, plan->index, n_fields); plan->tuple_exps = mem_heap_alloc(pars_sym_tab_global->heap, n_fields * sizeof(void*)); ut_memcpy(plan->tuple_exps, best_index_plan, n_fields * sizeof(void*)); if (best_last_op == '=') { plan->n_exact_match = n_fields; } else { plan->n_exact_match = n_fields - 1; } plan->mode = opt_op_to_search_mode(sel_node->asc, best_last_op); } if (dict_index_is_clust(best_index) && (plan->n_exact_match >= dict_index_get_n_unique(best_index))) { plan->unique_search = TRUE; } else { plan->unique_search = FALSE; } plan->old_vers_heap = NULL; btr_pcur_init(&(plan->pcur)); btr_pcur_init(&(plan->clust_pcur)); } /*******************************************************************//** Looks at a comparison condition and decides if it can, and need, be tested for a table AFTER the table has been accessed. @return OPT_NOT_COND if not for this table, else OPT_END_COND, OPT_TEST_COND, or OPT_SCROLL_COND, where the last means that the condition need not be tested, except when scroll cursors are used */ static ulint opt_classify_comparison( /*====================*/ sel_node_t* sel_node, /*!< in: select node */ ulint i, /*!< in: ith table in the join */ func_node_t* cond) /*!< in: comparison condition */ { plan_t* plan; ulint n_fields; ulint op; ulint j; ut_ad(cond && sel_node); plan = sel_node_get_nth_plan(sel_node, i); /* Check if the condition is determined after the ith table has been accessed, but not after the i - 1:th */ if (!opt_check_exp_determined_before(cond, sel_node, i + 1)) { return(OPT_NOT_COND); } if ((i > 0) && opt_check_exp_determined_before(cond, sel_node, i)) { return(OPT_NOT_COND); } /* If the condition is an exact match condition used in constructing the search tuple, it is classified as OPT_END_COND */ if (plan->tuple) { n_fields = dtuple_get_n_fields(plan->tuple); } else { n_fields = 0; } for (j = 0; j < plan->n_exact_match; j++) { if (opt_is_arg(plan->tuple_exps[j], cond)) { return(OPT_END_COND); } } /* If the condition is an non-exact match condition used in constructing the search tuple, it is classified as OPT_SCROLL_COND. When the cursor is positioned, and if a non-scroll cursor is used, there is no need to test this condition; if a scroll cursor is used the testing is necessary when the cursor is reversed. */ if ((n_fields > plan->n_exact_match) && opt_is_arg(plan->tuple_exps[n_fields - 1], cond)) { return(OPT_SCROLL_COND); } /* If the condition is a non-exact match condition on the first field in index for which there is no exact match, and it limits the search range from the opposite side of the search tuple already BEFORE we access the table, it is classified as OPT_END_COND */ if ((dict_index_get_n_fields(plan->index) > plan->n_exact_match) && opt_look_for_col_in_comparison_before( OPT_COMPARISON, dict_index_get_nth_col_no(plan->index, plan->n_exact_match), cond, sel_node, i, &op)) { if (sel_node->asc && ((op == '<') || (op == PARS_LE_TOKEN))) { return(OPT_END_COND); } if (!sel_node->asc && ((op == '>') || (op == PARS_GE_TOKEN))) { return(OPT_END_COND); } } /* Otherwise, cond is classified as OPT_TEST_COND */ return(OPT_TEST_COND); } /*******************************************************************//** Recursively looks for test conditions for a table in a join. */ static void opt_find_test_conds( /*================*/ sel_node_t* sel_node, /*!< in: select node */ ulint i, /*!< in: ith table in the join */ func_node_t* cond) /*!< in: conjunction of search conditions or NULL */ { func_node_t* new_cond; ulint class; plan_t* plan; if (cond == NULL) { return; } if (cond->func == PARS_AND_TOKEN) { new_cond = cond->args; opt_find_test_conds(sel_node, i, new_cond); new_cond = que_node_get_next(new_cond); opt_find_test_conds(sel_node, i, new_cond); return; } plan = sel_node_get_nth_plan(sel_node, i); class = opt_classify_comparison(sel_node, i, cond); if (class == OPT_END_COND) { UT_LIST_ADD_LAST(cond_list, plan->end_conds, cond); } else if (class == OPT_TEST_COND) { UT_LIST_ADD_LAST(cond_list, plan->other_conds, cond); } } /*******************************************************************//** Normalizes a list of comparison conditions so that a column of the table appears on the left side of the comparison if possible. This is accomplished by switching the arguments of the operator. */ static void opt_normalize_cmp_conds( /*====================*/ func_node_t* cond, /*!< in: first in a list of comparison conditions, or NULL */ dict_table_t* table) /*!< in: table */ { que_node_t* arg1; que_node_t* arg2; sym_node_t* sym_node; while (cond) { arg1 = cond->args; arg2 = que_node_get_next(arg1); if (que_node_get_type(arg2) == QUE_NODE_SYMBOL) { sym_node = arg2; if ((sym_node->token_type == SYM_COLUMN) && (sym_node->table == table)) { /* Switch the order of the arguments */ cond->args = arg2; que_node_list_add_last(NULL, arg2); que_node_list_add_last(arg2, arg1); /* Invert the operator */ cond->func = opt_invert_cmp_op(cond->func); } } cond = UT_LIST_GET_NEXT(cond_list, cond); } } /*******************************************************************//** Finds out the search condition conjuncts we can, and need, to test as the ith table in a join is accessed. The search tuple can eliminate the need to test some conjuncts. */ static void opt_determine_and_normalize_test_conds( /*===================================*/ sel_node_t* sel_node, /*!< in: select node */ ulint i) /*!< in: ith table in the join */ { plan_t* plan; plan = sel_node_get_nth_plan(sel_node, i); UT_LIST_INIT(plan->end_conds); UT_LIST_INIT(plan->other_conds); /* Recursively go through the conjuncts and classify them */ opt_find_test_conds(sel_node, i, sel_node->search_cond); opt_normalize_cmp_conds(UT_LIST_GET_FIRST(plan->end_conds), plan->table); ut_a(UT_LIST_GET_LEN(plan->end_conds) >= plan->n_exact_match); } /*******************************************************************//** Looks for occurrences of the columns of the table in the query subgraph and adds them to the list of columns if an occurrence of the same column does not already exist in the list. If the column is already in the list, puts a value indirection to point to the occurrence in the column list, except if the column occurrence we are looking at is in the column list, in which case nothing is done. */ UNIV_INTERN void opt_find_all_cols( /*==============*/ ibool copy_val, /*!< in: if TRUE, new found columns are added as columns to copy */ dict_index_t* index, /*!< in: index of the table to use */ sym_node_list_t* col_list, /*!< in: base node of a list where to add new found columns */ plan_t* plan, /*!< in: plan or NULL */ que_node_t* exp) /*!< in: expression or condition or NULL */ { func_node_t* func_node; que_node_t* arg; sym_node_t* sym_node; sym_node_t* col_node; ulint col_pos; if (exp == NULL) { return; } if (que_node_get_type(exp) == QUE_NODE_FUNC) { func_node = exp; arg = func_node->args; while (arg) { opt_find_all_cols(copy_val, index, col_list, plan, arg); arg = que_node_get_next(arg); } return; } ut_a(que_node_get_type(exp) == QUE_NODE_SYMBOL); sym_node = exp; if (sym_node->token_type != SYM_COLUMN) { return; } if (sym_node->table != index->table) { return; } /* Look for an occurrence of the same column in the plan column list */ col_node = UT_LIST_GET_FIRST(*col_list); while (col_node) { if (col_node->col_no == sym_node->col_no) { if (col_node == sym_node) { /* sym_node was already in a list: do nothing */ return; } /* Put an indirection */ sym_node->indirection = col_node; sym_node->alias = col_node; return; } col_node = UT_LIST_GET_NEXT(col_var_list, col_node); } /* The same column did not occur in the list: add it */ UT_LIST_ADD_LAST(col_var_list, *col_list, sym_node); sym_node->copy_val = copy_val; /* Fill in the field_no fields in sym_node */ sym_node->field_nos[SYM_CLUST_FIELD_NO] = dict_index_get_nth_col_pos( dict_table_get_first_index(index->table), sym_node->col_no); if (!dict_index_is_clust(index)) { ut_a(plan); col_pos = dict_index_get_nth_col_pos(index, sym_node->col_no); if (col_pos == ULINT_UNDEFINED) { plan->must_get_clust = TRUE; } sym_node->field_nos[SYM_SEC_FIELD_NO] = col_pos; } } /*******************************************************************//** Looks for occurrences of the columns of the table in conditions which are not yet determined AFTER the join operation has fetched a row in the ith table. The values for these column must be copied to dynamic memory for later use. */ static void opt_find_copy_cols( /*===============*/ sel_node_t* sel_node, /*!< in: select node */ ulint i, /*!< in: ith table in the join */ func_node_t* search_cond) /*!< in: search condition or NULL */ { func_node_t* new_cond; plan_t* plan; if (search_cond == NULL) { return; } ut_ad(que_node_get_type(search_cond) == QUE_NODE_FUNC); if (search_cond->func == PARS_AND_TOKEN) { new_cond = search_cond->args; opt_find_copy_cols(sel_node, i, new_cond); new_cond = que_node_get_next(new_cond); opt_find_copy_cols(sel_node, i, new_cond); return; } if (!opt_check_exp_determined_before(search_cond, sel_node, i + 1)) { /* Any ith table columns occurring in search_cond should be copied, as this condition cannot be tested already on the fetch from the ith table */ plan = sel_node_get_nth_plan(sel_node, i); opt_find_all_cols(TRUE, plan->index, &(plan->columns), plan, search_cond); } } /*******************************************************************//** Classifies the table columns according to whether we use the column only while holding the latch on the page, or whether we have to copy the column value to dynamic memory. Puts the first occurrence of a column to either list in the plan node, and puts indirections to later occurrences of the column. */ static void opt_classify_cols( /*==============*/ sel_node_t* sel_node, /*!< in: select node */ ulint i) /*!< in: ith table in the join */ { plan_t* plan; que_node_t* exp; plan = sel_node_get_nth_plan(sel_node, i); /* The final value of the following field will depend on the environment of the select statement: */ plan->must_get_clust = FALSE; UT_LIST_INIT(plan->columns); /* All select list columns should be copied: therefore TRUE as the first argument */ exp = sel_node->select_list; while (exp) { opt_find_all_cols(TRUE, plan->index, &(plan->columns), plan, exp); exp = que_node_get_next(exp); } opt_find_copy_cols(sel_node, i, sel_node->search_cond); /* All remaining columns in the search condition are temporary columns: therefore FALSE */ opt_find_all_cols(FALSE, plan->index, &(plan->columns), plan, sel_node->search_cond); } /*******************************************************************//** Fills in the info in plan which is used in accessing a clustered index record. The columns must already be classified for the plan node. */ static void opt_clust_access( /*=============*/ sel_node_t* sel_node, /*!< in: select node */ ulint n) /*!< in: nth table in select */ { plan_t* plan; dict_table_t* table; dict_index_t* clust_index; dict_index_t* index; mem_heap_t* heap; ulint n_fields; ulint pos; ulint i; plan = sel_node_get_nth_plan(sel_node, n); index = plan->index; /* The final value of the following field depends on the environment of the select statement: */ plan->no_prefetch = FALSE; if (dict_index_is_clust(index)) { plan->clust_map = NULL; plan->clust_ref = NULL; return; } table = index->table; clust_index = dict_table_get_first_index(table); n_fields = dict_index_get_n_unique(clust_index); heap = pars_sym_tab_global->heap; plan->clust_ref = dtuple_create(heap, n_fields); dict_index_copy_types(plan->clust_ref, clust_index, n_fields); plan->clust_map = mem_heap_alloc(heap, n_fields * sizeof(ulint)); for (i = 0; i < n_fields; i++) { pos = dict_index_get_nth_field_pos(index, clust_index, i); ut_a(pos != ULINT_UNDEFINED); /* We optimize here only queries to InnoDB's internal system tables, and they should not contain column prefix indexes. */ if (dict_index_get_nth_field(index, pos)->prefix_len != 0 || dict_index_get_nth_field(clust_index, i) ->prefix_len != 0) { fprintf(stderr, "InnoDB: Error in pars0opt.c:" " table %s has prefix_len != 0\n", index->table_name); } *(plan->clust_map + i) = pos; ut_ad(pos != ULINT_UNDEFINED); } } /*******************************************************************//** Optimizes a select. Decides which indexes to tables to use. The tables are accessed in the order that they were written to the FROM part in the select statement. */ UNIV_INTERN void opt_search_plan( /*============*/ sel_node_t* sel_node) /*!< in: parsed select node */ { sym_node_t* table_node; dict_table_t* table; order_node_t* order_by; ulint i; sel_node->plans = mem_heap_alloc(pars_sym_tab_global->heap, sel_node->n_tables * sizeof(plan_t)); /* Analyze the search condition to find out what we know at each join stage about the conditions that the columns of a table should satisfy */ table_node = sel_node->table_list; if (sel_node->order_by == NULL) { sel_node->asc = TRUE; } else { order_by = sel_node->order_by; sel_node->asc = order_by->asc; } for (i = 0; i < sel_node->n_tables; i++) { table = table_node->table; /* Choose index through which to access the table */ opt_search_plan_for_table(sel_node, i, table); /* Determine the search condition conjuncts we can test at this table; normalize the end conditions */ opt_determine_and_normalize_test_conds(sel_node, i); table_node = que_node_get_next(table_node); } table_node = sel_node->table_list; for (i = 0; i < sel_node->n_tables; i++) { /* Classify the table columns into those we only need to access but not copy, and to those we must copy to dynamic memory */ opt_classify_cols(sel_node, i); /* Calculate possible info for accessing the clustered index record */ opt_clust_access(sel_node, i); table_node = que_node_get_next(table_node); } /* Check that the plan obeys a possible order-by clause: if not, an assertion error occurs */ opt_check_order_by(sel_node); #ifdef UNIV_SQL_DEBUG opt_print_query_plan(sel_node); #endif } /********************************************************************//** Prints info of a query plan. */ UNIV_INTERN void opt_print_query_plan( /*=================*/ sel_node_t* sel_node) /*!< in: select node */ { plan_t* plan; ulint n_fields; ulint i; fputs("QUERY PLAN FOR A SELECT NODE\n", stderr); fputs(sel_node->asc ? "Asc. search; " : "Desc. search; ", stderr); if (sel_node->set_x_locks) { fputs("sets row x-locks; ", stderr); ut_a(sel_node->row_lock_mode == LOCK_X); ut_a(!sel_node->consistent_read); } else if (sel_node->consistent_read) { fputs("consistent read; ", stderr); } else { ut_a(sel_node->row_lock_mode == LOCK_S); fputs("sets row s-locks; ", stderr); } putc('\n', stderr); for (i = 0; i < sel_node->n_tables; i++) { plan = sel_node_get_nth_plan(sel_node, i); if (plan->tuple) { n_fields = dtuple_get_n_fields(plan->tuple); } else { n_fields = 0; } fputs("Table ", stderr); dict_index_name_print(stderr, NULL, plan->index); fprintf(stderr,"; exact m. %lu, match %lu, end conds %lu\n", (unsigned long) plan->n_exact_match, (unsigned long) n_fields, (unsigned long) UT_LIST_GET_LEN(plan->end_conds)); } }