MDEV-7856: EXPLAIN FORMAT=JSON should show partitions

1 files changed, 25 insertions, 33 deletions

diff --git a/sql/sql_explain.cc b/sql/sql_explain.cc
index 15f6753130c..3fbb720e6c5 100644
--- a/sql/sql_explain.cc
+++ b/sql/sql_explain.cc
@@ -37,6 +37,18 @@ Explain_query::Explain_query(THD *thd_arg, MEM_ROOT *root) :
 {
 }
 
+static void print_json_array(Json_writer *writer,
+                             const char *title, String_list &list)
+{
+  List_iterator_fast<char> it(list);
+  const char *name;
+  writer->add_member(title).start_array();
+  while ((name= it++))
+    writer->add_str(name);
+  writer->end_array();
+}
+
+
 
 Explain_query::~Explain_query()
 {
@@ -1219,17 +1231,9 @@ void add_json_keyset(Json_writer *writer, const char *elem_name,
                      String_list *keyset)
 {
   if (!keyset->is_empty())
-  {
-    List_iterator_fast<char> it(*keyset);
-    const char *name;
-    writer->add_member(elem_name).start_array();
-    while ((name= it++))
-      writer->add_str(name);
-    writer->end_array();
-  }
+    print_json_array(writer, elem_name, *keyset);
 }
 
-
 void Explain_table_access::print_explain_json(Explain_query *query,
                                               Json_writer *writer,
                                               bool is_analyze)
@@ -1252,7 +1256,10 @@ void Explain_table_access::print_explain_json(Explain_query *query,
   writer->add_member("table").start_object();
 
   writer->add_member("table_name").add_str(table_name);
-  // partitions
+
+  if (used_partitions_set)
+    print_json_array(writer, "partitions", used_partitions_list);
+
   writer->add_member("access_type").add_str(join_type_str[type]);
 
   add_json_keyset(writer, "possible_keys", &possible_keys);
@@ -1281,14 +1288,7 @@ void Explain_table_access::print_explain_json(Explain_query *query,
     parts_list= &key.key_parts_list;
 
   if (parts_list && !parts_list->is_empty())
-  {
-    List_iterator_fast<char> it(*parts_list);
-    const char *name;
-    writer->add_member("used_key_parts").start_array();
-    while ((name= it++))
-      writer->add_str(name);
-    writer->end_array();
-  }
+    print_json_array(writer, "used_key_parts", *parts_list);
 
   if (quick_info && !quick_info->is_basic())
   {
@@ -1299,14 +1299,7 @@ void Explain_table_access::print_explain_json(Explain_query *query,
   
   /* `ref` */
   if (!ref_list.is_empty())
-  {
-    List_iterator_fast<char> it(ref_list);
-    const char *str;
-    writer->add_member("ref").start_array();
-    while ((str= it++))
-      writer->add_str(str);
-    writer->end_array();
-  }
+    print_json_array(writer, "ref", ref_list);
 
   /* r_loops (not present in tabular output) */
   if (is_analyze)
@@ -1554,13 +1547,8 @@ void Explain_quick_select::print_json(Json_writer *writer)
     writer->add_member("range").start_object();
 
     writer->add_member("key").add_str(range.get_key_name());
-    
-    List_iterator_fast<char> it(range.key_parts_list);
-    const char *name;
-    writer->add_member("used_key_parts").start_array();
-    while ((name= it++))
-        writer->add_str(name);
-    writer->end_array();
+
+    print_json_array(writer, "used_key_parts", range.key_parts_list);
 
     writer->end_object();
   }
@@ -1845,6 +1833,10 @@ void Explain_update::print_explain_json(Explain_query *query,
     writer->add_member("delete").add_ll(1);
 
   writer->add_member("table_name").add_str(table_name);
+
+  if (used_partitions_set)
+    print_json_array(writer, "partitions", used_partitions_list);
+
   writer->add_member("access_type").add_str(join_type_str[jtype]);
 
   if (!possible_keys.is_empty())