MDEV-23143 Add JSON_EQUALS functionbb-10.7-mdev23143

This patch implements JSON_EQUALS SQL function.  The function takes
advantage of the json_normalize functionality and does the following:

norm_a = json_normalize(a)
norm_b = json_normalize(b)
return strcmp(norm_a, norm_b)

Co-authored-by: Vicențiu Ciorbaru <vicentiu@mariadb.org>

3 files changed, 101 insertions, 0 deletions

diff --git a/sql/item_create.cc b/sql/item_create.cc
index 79f558ee844..e019ac6f8bb 100644
--- a/sql/item_create.cc
+++ b/sql/item_create.cc
@@ -915,6 +915,19 @@ protected:
 };
 
 
+class Create_func_json_equals : public Create_func_arg2
+{
+public:
+  virtual Item *create_2_arg(THD *thd, Item *arg1, Item *arg2);
+
+  static Create_func_json_equals s_singleton;
+
+protected:
+  Create_func_json_equals() {}
+  virtual ~Create_func_json_equals() {}
+};
+
+
 class Create_func_json_exists : public Create_func_arg2
 {
 public:
@@ -3619,6 +3632,16 @@ Create_func_json_normalize::create_1_arg(THD *thd, Item *arg1)
 }
 
 
+Create_func_json_equals Create_func_json_equals::s_singleton;
+
+Item*
+Create_func_json_equals::create_2_arg(THD *thd, Item *arg1, Item *arg2)
+{
+  status_var_increment(thd->status_var.feature_json);
+  return new (thd->mem_root) Item_func_json_equals(thd, arg1, arg2);
+}
+
+
 Create_func_json_exists Create_func_json_exists::s_singleton;
 
 Item*
@@ -5574,6 +5597,7 @@ Native_func_registry func_array[] =
   { { STRING_WITH_LEN("JSON_CONTAINS_PATH") }, BUILDER(Create_func_json_contains_path)},
   { { STRING_WITH_LEN("JSON_DEPTH") }, BUILDER(Create_func_json_depth)},
   { { STRING_WITH_LEN("JSON_DETAILED") }, BUILDER(Create_func_json_detailed)},
+  { { STRING_WITH_LEN("JSON_EQUALS") }, BUILDER(Create_func_json_equals)},
   { { STRING_WITH_LEN("JSON_EXISTS") }, BUILDER(Create_func_json_exists)},
   { { STRING_WITH_LEN("JSON_EXTRACT") }, BUILDER(Create_func_json_extract)},
   { { STRING_WITH_LEN("JSON_INSERT") }, BUILDER(Create_func_json_insert)},
diff --git a/sql/item_jsonfunc.cc b/sql/item_jsonfunc.cc
index 32043b8f6a7..2fd729ba469 100644
--- a/sql/item_jsonfunc.cc
+++ b/sql/item_jsonfunc.cc
@@ -393,6 +393,66 @@ longlong Item_func_json_valid::val_int()
 }
 
 
+bool Item_func_json_equals::fix_length_and_dec()
+{
+  if (Item_bool_func::fix_length_and_dec())
+    return TRUE;
+  set_maybe_null();
+  return FALSE;
+}
+
+
+longlong Item_func_json_equals::val_int()
+{
+  longlong result= 0;
+
+  String a_tmp, b_tmp;
+
+  String *a= args[0]->val_json(&a_tmp);
+  String *b= args[1]->val_json(&b_tmp);
+
+  DYNAMIC_STRING a_res;
+  if (init_dynamic_string(&a_res, NULL, 0, 0))
+  {
+    null_value= 1;
+    return 1;
+  }
+
+  DYNAMIC_STRING b_res;
+  if (init_dynamic_string(&b_res, NULL, 0, 0))
+  {
+    dynstr_free(&a_res);
+    null_value= 1;
+    return 1;
+  }
+
+  if ((null_value= args[0]->null_value || args[1]->null_value))
+  {
+    null_value= 1;
+    goto end;
+  }
+
+  if (json_normalize(&a_res, a->c_ptr(), a->length(), a->charset()))
+  {
+    null_value= 1;
+    goto end;
+  }
+
+  if (json_normalize(&b_res, b->c_ptr(), b->length(), b->charset()))
+  {
+    null_value= 1;
+    goto end;
+  }
+
+  result= strcmp(a_res.str, b_res.str) ? 0 : 1;
+
+end:
+  dynstr_free(&b_res);
+  dynstr_free(&a_res);
+  return result;
+}
+
+
 bool Item_func_json_exists::fix_length_and_dec()
 {
   if (Item_bool_func::fix_length_and_dec())
diff --git a/sql/item_jsonfunc.h b/sql/item_jsonfunc.h
index 04d06a0ebf7..518a98d95df 100644
--- a/sql/item_jsonfunc.h
+++ b/sql/item_jsonfunc.h
@@ -107,6 +107,23 @@ public:
 };
 
 
+class Item_func_json_equals: public Item_bool_func
+{
+public:
+  Item_func_json_equals(THD *thd, Item *a, Item *b):
+    Item_bool_func(thd, a, b) {}
+  LEX_CSTRING func_name_cstring() const override
+  {
+    static LEX_CSTRING name= {STRING_WITH_LEN("json_equals") };
+    return name;
+  }
+  bool fix_length_and_dec() override;
+  Item *get_copy(THD *thd) override
+  { return get_item_copy<Item_func_json_equals>(thd, this); }
+  longlong val_int() override;
+};
+
+
 class Item_func_json_exists: public Item_bool_func
 {
 protected: