MDEV-20440: Optimizer trace: print more details about semi-join optimization

Followup patch: fix typos

Author: spetrunia

mysql-test/main/opt_trace.result

@@ -2970,7 +2970,7 @@ explain extended select * from t1 where a in (select pk from t10)	{
                         "read_time": 27.129
                       },
                       {
-                        "chosen_strategy": "SJ-Materialize"
+                        "chosen_strategy": "SJ-Materialization"
                       }
                     ],
                     "estimated_join_cardinality": 3
@@ -4609,7 +4609,7 @@ explain select * from t1 where a in (select t_inner_1.a from t1 t_inner_1, t1 t_
                             "read_time": 18.315
                           },
                           {
-                            "chosen_strategy": "SJ-Materialize"
+                            "chosen_strategy": "SJ-Materialization"
                           }
                         ],
                         "estimated_join_cardinality": 3
@@ -6309,7 +6309,14 @@ t_outer_2.a in (select t_inner_3.a from t2 t_inner_3, t1 t_inner_4)	{
             ]
           },
           {
-            "fix_semijoin_strategies_for_picked_join_order": []
+            "fix_semijoin_strategies_for_picked_join_order": [
+              {
+                "semi_join_strategy": "DuplicateWeedout"
+              },
+              {
+                "semi_join_strategy": "DuplicateWeedout"
+              }
+            ]
           },
           {
             "best_join_order": [
@@ -6833,7 +6840,7 @@ t_outer_2.a in (select t_inner_3.a from t2 t_inner_3, t1 t_inner_4)	{
                             "read_time": 37.226
                           },
                           {
-                            "chosen_strategy": "SJ-Materialize"
+                            "chosen_strategy": "SJ-Materialization"
                           }
                         ],
                         "rest_of_plan": [
@@ -6935,7 +6942,7 @@ t_outer_2.a in (select t_inner_3.a from t2 t_inner_3, t1 t_inner_4)	{
                                         "read_time": 294.96
                                       },
                                       {
-                                        "chosen_strategy": "SJ-Materialize"
+                                        "chosen_strategy": "SJ-Materialization"
                                       }
                                     ],
                                     "estimated_join_cardinality": 27

sql/opt_subselect.cc

@@ -2938,10 +2938,10 @@ void advance_sj_state(JOIN *join, table_map remaining_tables, uint idx,
       const char *sname;
       switch (pos->sj_strategy) {
         case SJ_OPT_MATERIALIZE:
-          sname= "SJ-Materialize";
+          sname= "SJ-Materialization";
           break;
         case SJ_OPT_MATERIALIZE_SCAN:
-          sname= "SJ-Materialize-Scan";
+          sname= "SJ-Materialization-Scan";
           break;
         case SJ_OPT_FIRST_MATCH:
           sname= "FirstMatch";
@@ -3203,7 +3203,7 @@ bool LooseScan_picker::check_qep(JOIN *join,
       (new_join_tab->table->map & loosescan_need_tables))
   {
     Json_writer_object trace(join->thd);
-    trace.add("strategy", "SJ-Materialization-Scan");
+    trace.add("strategy", "LooseScan");
     /* 
       Ok we have LooseScan plan and also have all LooseScan sj-nest's
       inner tables and outer correlated tables into the prefix.
@@ -3899,6 +3899,8 @@ void fix_semijoin_strategies_for_picked_join_order(JOIN *join)
 
     if (pos->sj_strategy == SJ_OPT_DUPS_WEEDOUT)
     {
+      Json_writer_object semijoin_strategy(thd);
+      semijoin_strategy.add("semi_join_strategy","DuplicateWeedout");
       /* 
         Duplicate Weedout starting at pos->first_dupsweedout_table, ending at
         this table.