diff options
Diffstat (limited to 'sql/opt_split.cc')
| -rw-r--r-- | sql/opt_split.cc | 35 |
1 files changed, 21 insertions, 14 deletions
diff --git a/sql/opt_split.cc b/sql/opt_split.cc index 8cb82693d96..8848c1820df 100644 --- a/sql/opt_split.cc +++ b/sql/opt_split.cc @@ -188,6 +188,7 @@ #include "mariadb.h" #include "sql_select.h" #include "opt_trace.h" +#include "optimizer_defaults.h" /* Info on a splitting field */ struct SplM_field_info @@ -665,6 +666,8 @@ add_ext_keyuses_for_splitting_field(Dynamic_array<KEYUSE_EXT> *ext_keyuses, /* @brief Cost of the post join operation used in specification of splittable table + This does not include the cost of creating the temporary table as this + operation can be executed many times for the same temporary table. */ static @@ -673,13 +676,18 @@ double spl_postjoin_oper_cost(THD *thd, double join_record_count, uint rec_len) double cost; TMPTABLE_COSTS tmp_cost= get_tmp_table_costs(thd, join_record_count, rec_len, 0, 1); - // cost to fill tmp table - cost= tmp_cost.create + tmp_cost.write * join_record_count; - // cost to perform post join operation used here + /* cost to fill tmp table */ + cost= tmp_cost.write * join_record_count; + /* cost to perform post join operation used here */ cost+= tmp_cost.lookup * join_record_count; - cost+= (join_record_count == 0 ? 0 : - join_record_count * log2 (join_record_count)) * - SORT_INDEX_CMP_COST; // cost to perform sorting + /* cost to preform sorting */ + /* QQQ + We should use cost_of_filesort() for computing sort. + Do we always preform sorting ? If not, this should be done conditionally + */ + cost+= ((join_record_count == 0 ? 0 : + join_record_count * log2 (join_record_count)) * + SORT_INDEX_CMP_COST); return cost; } @@ -873,7 +881,7 @@ void reset_validity_vars_for_keyuses(KEYUSE_EXT *key_keyuse_ext_start, splitting the function set it as the true plan of materialization of the table T. The function caches the found plans for materialization of table T - together if the info what key was used for splitting. Next time when + together with the info what key was used for splitting. Next time when the optimizer prefers to use the same key the plan is taken from the cache of plans @@ -1004,12 +1012,11 @@ SplM_plan_info * JOIN_TAB::choose_best_splitting(double record_count, spl_opt_info->unsplit_card : 1); uint rec_len= table->s->rec_buff_length; - double split_card= spl_opt_info->unsplit_card * spl_plan->split_sel; - double oper_cost= split_card * - spl_postjoin_oper_cost(thd, split_card, rec_len); - spl_plan->cost= join->best_positions[join->table_count-1].read_time + - + oper_cost; + double oper_cost= (split_card * + spl_postjoin_oper_cost(thd, split_card, rec_len)); + spl_plan->cost= (join->best_positions[join->table_count-1].read_time + + oper_cost); if (unlikely(thd->trace_started())) { @@ -1030,7 +1037,7 @@ SplM_plan_info * JOIN_TAB::choose_best_splitting(double record_count, } if (spl_plan) { - if(record_count * spl_plan->cost < spl_opt_info->unsplit_cost - 0.01) + if (record_count * spl_plan->cost + COST_EPS < spl_opt_info->unsplit_cost) { /* The best plan that employs splitting is cheaper than @@ -1054,7 +1061,7 @@ SplM_plan_info * JOIN_TAB::choose_best_splitting(double record_count, trace. add("startup_cost", startup_cost). add("splitting_cost", spl_plan->cost). - add("records", records); + add("rows", records); } } else |