MDEV-22014: Rowid Filtering is not displayed well in the optimizer tracebb-10.5-mdev22014

- Print the rowid filters that are available for use with each table.
- Make print_best_access_for_table() print which filter it has picked.
- Make best_access_path() print the filter for considered ref accesses.

5 files changed, 47 insertions, 8 deletions

diff --git a/sql/opt_trace.cc b/sql/opt_trace.cc
index a8676eec411..ddec6d5ed2d 100644
--- a/sql/opt_trace.cc
+++ b/sql/opt_trace.cc
@@ -24,6 +24,8 @@
 #include "my_json_writer.h"
 #include "sp_head.h"
 
+#include "rowid_filter.h"
+
 const char I_S_table_name[]= "OPTIMIZER_TRACE";
 
 /**
@@ -664,14 +666,17 @@ void print_best_access_for_table(THD *thd, POSITION *pos,
 {
   DBUG_ASSERT(thd->trace_started());
 
-  Json_writer_object trace_best_access(thd, "chosen_access_method");
-  trace_best_access.add("type", type == JT_ALL ? "scan" :
-                                                 join_type_str[type]);
-  trace_best_access.add("records", pos->records_read);
-  trace_best_access.add("cost", pos->read_time);
-  trace_best_access.add("uses_join_buffering", pos->use_join_buffer);
-  trace_best_access.add("filter_used",
-                         pos->range_rowid_filter_info != NULL);
+  Json_writer_object obj(thd, "chosen_access_method");
+  obj.add("type", type == JT_ALL ? "scan" : join_type_str[type]);
+  obj.add("records", pos->records_read);
+  obj.add("cost", pos->read_time);
+  obj.add("uses_join_buffering", pos->use_join_buffer);
+  if (pos->range_rowid_filter_info)
+  {
+    uint key_no= pos->range_rowid_filter_info->key_no;
+    obj.add("rowid_filter_key",
+            pos->table->table->key_info[key_no].name);
+  }
 }
 
 
diff --git a/sql/rowid_filter.cc b/sql/rowid_filter.cc
index 865f22b431a..6ab9e40de32 100644
--- a/sql/rowid_filter.cc
+++ b/sql/rowid_filter.cc
@@ -20,6 +20,7 @@
 #include "opt_range.h"
 #include "rowid_filter.h"
 #include "sql_select.h"
+#include "opt_trace.h"
 
 
 inline
@@ -403,9 +404,37 @@ void TABLE::init_cost_info_for_usable_range_rowid_filters(THD *thd)
   }
 
   prune_range_rowid_filters();
+
+  if (unlikely(thd->trace_started()))
+    trace_range_rowid_filters(thd);
 }
 
 
+void TABLE::trace_range_rowid_filters(THD *thd) const
+{
+  if (!range_rowid_filter_cost_info_elems)
+    return;
+
+  Range_rowid_filter_cost_info **p= range_rowid_filter_cost_info_ptr;
+  Range_rowid_filter_cost_info **end= p + range_rowid_filter_cost_info_elems;
+
+  Json_writer_object js_obj(thd);
+  js_obj.add_table_name(this);
+  Json_writer_array js_arr(thd, "rowid_filters");
+
+  for (; p < end; p++)
+    (*p)->trace_info(thd);
+}
+
+
+void Range_rowid_filter_cost_info::trace_info(THD *thd)
+{
+  Json_writer_object js_obj(thd);
+  js_obj.add("key", table->key_info[key_no].name);
+  js_obj.add("build_cost", b);
+  js_obj.add("rows", est_elements);
+}
+
 /**
   @brief
     Choose the best range filter for the given access of the table
diff --git a/sql/rowid_filter.h b/sql/rowid_filter.h
index a9930dcbca8..467b6884ca6 100644
--- a/sql/rowid_filter.h
+++ b/sql/rowid_filter.h
@@ -452,6 +452,8 @@ public:
 
   double get_a() { return a; }
 
+  void trace_info(THD *thd);
+
   friend
   void TABLE::prune_range_rowid_filters();
 
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 35b5665d1d0..d8d984404cd 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -7756,6 +7756,8 @@ best_access_path(JOIN      *join,
           filter->get_cmp_gain(rows);
           tmp-= filter->get_adjusted_gain(rows) - filter->get_cmp_gain(rows);
           DBUG_ASSERT(tmp >= 0);
+          trace_access_idx.add("rowid_filter_key",
+                               s->table->key_info[filter->key_no].name);
         }
       }
       trace_access_idx.add("rows", records).add("cost", tmp);
diff --git a/sql/table.h b/sql/table.h
index 9430ceb5fe3..13eaee869ce 100644
--- a/sql/table.h
+++ b/sql/table.h
@@ -1579,6 +1579,7 @@ public:
 
   void init_cost_info_for_usable_range_rowid_filters(THD *thd);
   void prune_range_rowid_filters();
+  void trace_range_rowid_filters(THD *thd) const;
   Range_rowid_filter_cost_info *
   best_range_rowid_filter_for_partial_join(uint access_key_no,
                                            double records,