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Fixed MDEV-14994 Assertion `join->best_read < double(1.79...15e+308L)' or

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server crash in JOIN::fix_all_splittings_in_plan

Cost formulas must take into account the case when a splittable table
has now rows.
This commit is contained in:
Igor Babaev
2018-01-30 21:12:11 -08:00
parent a1e0e64a47
commit 7a9611aee2
3 changed files with 37 additions and 2 deletions
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7
sql/opt_split.cc
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@ -645,7 +645,8 @@ double spl_postjoin_oper_cost(THD *thd, double join_record_count, uint rec_len)
cost+= get_tmp_table_lookup_cost(thd, join_record_count,rec_len) *
join_record_count; // cost to perform post join operation used here
cost+= get_tmp_table_lookup_cost(thd, join_record_count, rec_len) +
join_record_count * log2 (join_record_count) *
(join_record_count == 0 ? 0 :
join_record_count * log2 (join_record_count)) *
SORT_INDEX_CMP_COST; // cost to perform sorting
return cost;
}
@ -948,7 +949,9 @@ SplM_plan_info * JOIN_TAB::choose_best_splitting(double record_count,
spl_plan->table= best_table;
spl_plan->key= best_key;
spl_plan->parts= best_key_parts;
spl_plan->split_sel= best_rec_per_key / spl_opt_info->unsplit_card;
spl_plan->split_sel= best_rec_per_key /
(spl_opt_info->unsplit_card ?
spl_opt_info->unsplit_card : 1);
uint rec_len= table->s->rec_buff_length;