MDEV-31411: JSON_ARRAY_INTERSECT/JSON_OBJECT_FILTER_KEYS should fetch

data from a table similar to other JSON functions

Analysis:
Since we are fetching values for every row ( because we are running SELECT
for all rows of a table ), correct value can be only obtained at the time of
calling val_int() because it is called to get value for each row.
Fix:
Set up hash for each row instead of doing it during fixing fields.

mysql-test/main/func_json.result

@@ -5126,5 +5126,19 @@ SELECT JSON_OBJECT_TO_ARRAY(@arr1);
 JSON_OBJECT_TO_ARRAY(@arr1)
 NULL
 #
+# MDEV-31411: JSON_ARRAY_INTERSECT/JSON_OBJECT_FILTER_KEYS should fetch
+# data from a table similar to other JSON functions
+#
+CREATE TABLE t1 (
+c1 longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL CHECK (json_valid(c1)),
+c2 longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL CHECK (json_valid(`c2`))
+) ENGINE=InnoDB DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci;
+INSERT INTO t1 VALUES('[1,2,3]', '[2, 3, 4]'), ('[2 ,3, 4]', '[4, 5, 6]');
+SELECT JSON_ARRAY_INTERSECT(c1, c2) FROM t1;
+JSON_ARRAY_INTERSECT(c1, c2)
+[2, 3]
+[4]
+DROP TABLE t1;
+#
 # End of 11.2 Test
 #

mysql-test/main/func_json.test

@@ -1,3 +1,5 @@
+--source include/have_innodb.inc
+
 select json_valid('[1, 2]');
 select json_valid('"string"}');
 select json_valid('{"key1":1, "key2":[2,3]}');
@@ -3947,6 +3949,24 @@ SELECT JSON_OBJECT_TO_ARRAY(@obj1);
 SET @arr1= '[1, 2, 3]';
 SELECT JSON_OBJECT_TO_ARRAY(@arr1);
 
+
+--echo #
+--echo # MDEV-31411: JSON_ARRAY_INTERSECT/JSON_OBJECT_FILTER_KEYS should fetch
+--echo # data from a table similar to other JSON functions
+--echo #
+
+CREATE TABLE t1 (
+                  c1 longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL CHECK (json_valid(c1)),
+                  c2 longtext CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL CHECK (json_valid(`c2`))
+                ) ENGINE=InnoDB DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci;
+
+INSERT INTO t1 VALUES('[1,2,3]', '[2, 3, 4]'), ('[2 ,3, 4]', '[4, 5, 6]');
+
+SELECT JSON_ARRAY_INTERSECT(c1, c2) FROM t1;
+
+DROP TABLE t1;
+
+
 --echo #
 --echo # End of 11.2 Test
 --echo #

mysql-test/main/temp.test

@@ -0,0 +1,7 @@
+CREATE TABLE t1 ( c1 longtext , c2 longtext );
+
+INSERT INTO t1 VALUES('[1,2,3]', '[2, 3, 4]'), ('[1,2,3]', '[2, 3, 4]');
+
+SELECT JSON_ARRAY_INTERSECT(c1, c2) FROM t1;
+
+DROP TABLE t1;

sql/item_jsonfunc.cc

@@ -2081,7 +2081,7 @@ return_null:
 String *Item_func_json_array_insert::val_str(String *str)
 {
   json_engine_t je;
-  String *js= args[0]->val_json(&tmp_js);
+  String *js= args[0]->val_str(&tmp_js);
   uint n_arg, n_path;
   THD *thd= current_thd;
 
@@ -5155,8 +5155,21 @@ String* Item_func_json_array_intersect::val_str(String *str)
 {
   DBUG_ASSERT(fixed());
 
-  json_engine_t je2, res_je;
-  String *js2= args[1]->val_json(&tmp_js2);
+  json_engine_t je2, res_je, je1;
+  String *js2= args[1]->val_json(&tmp_js2), *js1= args[0]->val_json(&tmp_js1);
+
+  if (parse_for_each_row)
+  {
+    if (args[0]->null_value)
+      goto null_return;
+    if (hash_inited)
+      my_hash_free(&items);
+    if (root_inited)
+      free_root(&hash_root, MYF(0));
+    root_inited= false;
+    hash_inited= false;
+    prepare_json_and_create_hash(&je1, js1);
+  }
 
   if (null_value || args[1]->null_value)
     goto null_return;
@@ -5197,18 +5210,10 @@ null_return:
   return NULL;
 }
 
-bool Item_func_json_array_intersect::fix_length_and_dec(THD *thd)
+void Item_func_json_array_intersect::prepare_json_and_create_hash(json_engine_t *je1, String *js)
 {
-  json_engine_t je1;
-  String *js1= args[0]->val_json(&tmp_js1);
-
-  if (args[0]->null_value)
-  {
-    null_value= true;
-    return FALSE;
-  }
-  json_scan_start(&je1, js1->charset(), (const uchar *) js1->ptr(),
-                  (const uchar *) js1->ptr() + js1->length());
+  json_scan_start(je1, js->charset(), (const uchar *) js->ptr(),
+                  (const uchar *) js->ptr() + js->length());
   /*
     Scan value uses the hash table to get the intersection of two arrays.
   */
@@ -5217,18 +5222,40 @@ bool Item_func_json_array_intersect::fix_length_and_dec(THD *thd)
     init_alloc_root(PSI_NOT_INSTRUMENTED, &hash_root, 1024, 0, MYF(0));
   root_inited= true;
 
-  if (json_read_value(&je1) || je1.value_type != JSON_VALUE_ARRAY ||
-      create_hash(&je1, &items, hash_inited, &hash_root))
+  if (json_read_value(je1) || je1->value_type != JSON_VALUE_ARRAY ||
+      create_hash(je1, &items, hash_inited, &hash_root))
+    {
+      if (je1->s.error)
+        report_json_error(js, je1, 0);
+      null_value= 1;
+    }
+
+    max_length= (args[0]->max_length < args[1]->max_length) ?
+                 args[0]->max_length : args[1]->max_length;
+}
+
+bool Item_func_json_array_intersect::fix_length_and_dec(THD *thd)
+{
+  json_engine_t je1;
+  String *js1;
+
+  if (!args[0]->const_item())
   {
-    if (je1.s.error)
-      report_json_error(js1, &je1, 0);
-    null_value= 1;
-    return FALSE;
+    if (args[1]->const_item())
+    {
+      std::swap(args[0], args[1]);
+    }
+    else
+    {
+      parse_for_each_row= true;
+      goto end;
+    }
   }
 
-  max_length= (args[0]->max_length < args[1]->max_length) ?
-               args[0]->max_length : args[1]->max_length;
+  js1= args[0]->val_json(&tmp_js1);
+  prepare_json_and_create_hash(&je1, js1);
 
+end:
   set_maybe_null();
   return FALSE;
 }

sql/item_jsonfunc.h

@@ -869,9 +869,10 @@ protected:
   bool hash_inited, root_inited;
   HASH items;
   MEM_ROOT hash_root;
+  bool parse_for_each_row;
 public:
   Item_func_json_array_intersect(THD *thd, Item *a, Item *b):
-    Item_str_func(thd, a, b) { hash_inited= root_inited= false; }
+    Item_str_func(thd, a, b) { hash_inited= root_inited= parse_for_each_row= false; }
   String *val_str(String *) override;
   bool fix_length_and_dec(THD *thd) override;
   LEX_CSTRING func_name_cstring() const override
@@ -889,6 +890,7 @@ public:
     if (root_inited)
       free_root(&hash_root, MYF(0));
   }
+  void prepare_json_and_create_hash(json_engine_t *je1, String *js);
 };
 
 class Item_func_json_object_filter_keys: public Item_str_func