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@spetrunia
Created Oct 3, 2022
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diff --git a/sql/opt_subselect.cc b/sql/opt_subselect.cc
index f121a592d5b..ac447286a56 100644
--- a/sql/opt_subselect.cc
+++ b/sql/opt_subselect.cc
@@ -3635,12 +3636,12 @@ bool Duplicate_weedout_picker::check_qep(JOIN *join,
if (p->table->emb_sj_nest)
{
- sj_inner_fanout= COST_MULT(sj_inner_fanout, p->records_read);
+ sj_inner_fanout= COST_MULT(sj_inner_fanout, p->records_out);
dups_removed_fanout |= p->table->table->map;
}
else
{
- sj_outer_fanout= COST_MULT(sj_outer_fanout, p->records_read);
+ sj_outer_fanout= COST_MULT(sj_outer_fanout, p->records_out);
temptable_rec_size += p->table->table->file->ref_length;
}
}
@@ -3659,10 +3660,9 @@ bool Duplicate_weedout_picker::check_qep(JOIN *join,
sj_outer_fanout,
temptable_rec_size,
0, 0);
- double prefix_record_count= join->positions[first_tab].prefix_record_count;
double write_cost= (one_cost.create +
- prefix_record_count * sj_outer_fanout * one_cost.write);
- double full_lookup_cost= (prefix_record_count * sj_outer_fanout *
+ first_weedout_table_rec_count * sj_outer_fanout * one_cost.write);
+ double full_lookup_cost= (first_weedout_table_rec_count* sj_outer_fanout *
sj_inner_fanout * one_cost.lookup);
*read_time= dups_cost + write_cost + full_lookup_cost;
@@ -3674,7 +3674,7 @@ bool Duplicate_weedout_picker::check_qep(JOIN *join,
Json_writer_object trace(join->thd);
trace.
add("strategy", "DuplicateWeedout").
- add("prefix_record_count", prefix_record_count).
+ add("prefix_record_count", first_weedout_table_rec_count).
add("tmp_table_records", sj_outer_fanout).
add("sj_inner_fanout", sj_inner_fanout).
add("rows", *record_count).
diff --git a/sql/opt_subselect.h b/sql/opt_subselect.h
index 2eb5ff56b02..f59ce0dbb85 100644
--- a/sql/opt_subselect.h
+++ b/sql/opt_subselect.h
@@ -300,6 +300,7 @@ class Loose_scan_opt
if (best_loose_scan_cost != DBL_MAX)
{
pos->records_read= best_loose_scan_records;
+ pos->records_init= pos->records_out= pos->records_read;
pos->key= best_loose_scan_start_key;
pos->cond_selectivity= 1.0;
pos->loosescan_picker.loosescan_key= best_loose_scan_key;
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 02976201411..8517861f6c6 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -18250,6 +18280,14 @@ void optimize_wo_join_buffering(JOIN *join, uint first_tab, uint last_tab,
join->cur_sj_inner_tables= save_cur_sj_inner_tables;
*reopt_cost= cost;
+ if (rec_count < *outer_rec_count)
+ {
+ /*
+ The tables inside the subquery produce smaller fanout than outer tables.
+ This can happen in edge cases.
+ */
+ *outer_rec_count= rec_count;
+ }
}
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