MDEV-22844 JSON_ARRAYAGG is limited by group_concat_max_len.

Warning message and function result fixed

mysql-test/main/func_json.result

@@ -1308,6 +1308,18 @@ SELECT JSON_ARRAYAGG(a ORDER BY a ASC) FROM t1;
 JSON_ARRAYAGG(a ORDER BY a ASC)
 [null,"blue","red"]
 DROP TABLE t1;
+set group_concat_max_len=64;
+create table t1 (a varchar(254));
+insert into t1 values (concat('x64-', repeat('a', 60)));
+insert into t1 values (concat('x64-', repeat('b', 60)));
+insert into t1 values (concat('x64-', repeat('c', 60)));
+select json_arrayagg(a) from t1;
+json_arrayagg(a)
+["x64-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"]
+Warnings:
+Warning	1260	Row 1 was cut by JSON_ARRAYAGG()
+drop table t1;
+SET group_concat_max_len= default;
 #
 # End of 10.5 tests
 #

mysql-test/main/func_json.test

@@ -812,6 +812,14 @@ SELECT JSON_ARRAYAGG(a ORDER BY a DESC) FROM t1;
 SELECT JSON_ARRAYAGG(a ORDER BY a ASC) FROM t1;
 DROP TABLE t1;
 
+set group_concat_max_len=64;
+create table t1 (a varchar(254));
+insert into t1 values (concat('x64-', repeat('a', 60)));
+insert into t1 values (concat('x64-', repeat('b', 60)));                                            insert into t1 values (concat('x64-', repeat('c', 60)));
+select json_arrayagg(a) from t1; 
+drop table t1;
+SET group_concat_max_len= default;
+
 --echo #
 --echo # End of 10.5 tests
 --echo #

sql/item_jsonfunc.cc

@@ -3689,6 +3689,24 @@ String *Item_func_json_arrayagg::get_str_from_field(Item *i,Field *f,
 }
 
 
+void Item_func_json_arrayagg::cut_max_length(String *result,
+       uint old_length, uint max_length) const
+{
+  if (result->length() == 0)
+    return;
+
+  if (result->ptr()[result->length() - 1] != '"' ||
+      max_length == 0)
+  {
+    Item_func_group_concat::cut_max_length(result, old_length, max_length);
+    return;
+  }
+
+  Item_func_group_concat::cut_max_length(result, old_length, max_length-1);
+  result->append('"');
+}
+
+
 String* Item_func_json_arrayagg::val_str(String *str)
 {
   if ((str= Item_func_group_concat::val_str(str)))

sql/item_jsonfunc.h

@@ -546,7 +546,8 @@ class Item_func_json_arrayagg : public Item_func_group_concat
   String *get_str_from_item(Item *i, String *tmp);
   String *get_str_from_field(Item *i, Field *f, String *tmp,
                              const uchar *key, size_t offset);
-
+  void cut_max_length(String *result,
+                      uint old_length, uint max_length) const;
 public:
   String m_tmp_json; /* Used in get_str_from_*.. */
   Item_func_json_arrayagg(THD *thd, Name_resolution_context *context_arg,

sql/item_sum.cc

@@ -3733,6 +3733,37 @@ int group_concat_key_cmp_with_order_with_nulls(void *arg, const void *key1_arg,
 }
 
 
+static void report_cut_value_error(THD *thd, uint row_count, const char *fname)
+{
+  size_t fn_len= strlen(fname);
+  char *fname_upper= (char *) my_alloca(fn_len + 1);
+  fname_upper[fn_len]= 0;
+  for (; fn_len; fn_len--)
+    fname_upper[fn_len-1]= my_toupper(&my_charset_latin1, fname[fn_len-1]);
+  push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
+                      ER_CUT_VALUE_GROUP_CONCAT,
+                      ER_THD(thd, ER_CUT_VALUE_GROUP_CONCAT),
+                      row_count, fname_upper);
+}
+
+
+void Item_func_group_concat::cut_max_length(String *result,
+        uint old_length, uint max_length) const
+{
+  const char *ptr= result->ptr();
+  /*
+    It's ok to use item->result.length() as the fourth argument
+    as this is never used to limit the length of the data.
+    Cut is done with the third argument.
+  */
+  size_t add_length= Well_formed_prefix(collation.collation,
+                                      ptr + old_length,
+                                      ptr + max_length,
+                                      result->length()).length();
+  result->length(old_length + add_length);
+}
+
+
 /**
   Append data from current leaf to item->result.
 */
@@ -3812,24 +3843,10 @@ int dump_leaf_key(void* key_arg, element_count count __attribute__((unused)),
   /* stop if length of result more than max_length */
   if (result->length() > max_length)
   {
-    CHARSET_INFO *cs= item->collation.collation;
-    const char *ptr= result->ptr();
     THD *thd= current_thd;
-    /*
-      It's ok to use item->result.length() as the fourth argument
-      as this is never used to limit the length of the data.
-      Cut is done with the third argument.
-    */
-    size_t add_length= Well_formed_prefix(cs,
-                                        ptr + old_length,
-                                        ptr + max_length,
-                                        result->length()).length();
-    result->length(old_length + add_length);
+    item->cut_max_length(result, old_length, max_length);
     item->warning_for_row= TRUE;
-    push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
-                        ER_CUT_VALUE_GROUP_CONCAT,
-                        ER_THD(thd, ER_CUT_VALUE_GROUP_CONCAT),
-                        item->row_count);
+    report_cut_value_error(thd, item->row_count, item->func_name());
 
     /**
        To avoid duplicated warnings in Item_func_group_concat::val_str()
@@ -4427,9 +4444,7 @@ String* Item_func_group_concat::val_str(String* str)
       table->blob_storage->is_truncated_value())
   {
     warning_for_row= true;
-    push_warning_printf(current_thd, Sql_condition::WARN_LEVEL_WARN,
-                        ER_CUT_VALUE_GROUP_CONCAT, ER(ER_CUT_VALUE_GROUP_CONCAT),
-                        row_count);
+    report_cut_value_error(current_thd, row_count, func_name());
   }
 
   return &result;

sql/item_sum.h

@@ -1941,6 +1941,8 @@ class Item_func_group_concat : public Item_sum
   virtual String *get_str_from_field(Item *i, Field *f, String *tmp,
                                      const uchar *key, size_t offset)
     { return f->val_str(tmp, key + offset); }
+  virtual void cut_max_length(String *result,
+                              uint old_length, uint max_length) const;
 public:
   // Methods used by ColumnStore
   bool get_distinct() const { return distinct; }

sql/share/errmsg-utf8.txt

@@ -4940,7 +4940,7 @@ ER_ZLIB_Z_DATA_ERROR
         por "ZLIB: Dados de entrada está corrupto"
         spa "ZLIB: Dato de entrada fué corrompido para zlib"
 ER_CUT_VALUE_GROUP_CONCAT  
-        eng "Row %u was cut by GROUP_CONCAT()"
+        eng "Row %u was cut by %s)"
 ER_WARN_TOO_FEW_RECORDS 01000 
         eng "Row %lu doesn't contain data for all columns"
         ger "Zeile %lu enthält nicht für alle Felder Daten"