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>

1 files changed, 60 insertions, 0 deletions

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())