MDEV-25727 Add FORMAT JSON support to JSON_TABLE

Allow explicit FORMAT JSON columns in JSON_TABLE for supported string, blob, and JSON targets. Preserve the explicit clause in view printing and add regression coverage for formatted extraction, unsupported targets, and SHOW CREATE VIEW. Signed-off-by: Varun Deep Saini <varun.23bcs10048@ms.sst.scaler.com> Signed-off-by: Varun Deep Saini <deepsainivarun@gmail.com>
2026-10-23 18:49:29 +03:00 · 2026-03-06 15:26:00 +05:30
parent f40ea8f4e6
commit c3ec2dc368
5 changed files with 193 additions and 6 deletions
--- a/mysql-test/suite/json/r/json_table_mysql.result
+++ b/mysql-test/suite/json/r/json_table_mysql.result
@@ -106,6 +106,86 @@ id	jpath	json_path	jexst
 3	NULL	NULL	1
 select * from
 json_table(
+'[{"name":"Jeans","sizes":[32,34,36],"details":{"fit":"regular"},"flag":true,"jsnull":null},
+      {"name":"T-Shirt","sizes":["Medium","Large"],"details":{"fit":"loose"},"flag":false,"jsnull":null},
+      {"name":"Cellphone"}]',
+'$[*]' columns (name varchar(10) path '$.name',
+sizes varchar(100) format json path '$.sizes',
+details text format json path '$.details',
+flag varchar(10) format json path '$.flag',
+jsnull varchar(10) format json path '$.jsnull')
+) as jt;
+name	sizes	details	flag	jsnull
+Jeans	[32,34,36]	{"fit":"regular"}	true	null
+T-Shirt	["Medium","Large"]	{"fit":"loose"}	false	null
+Cellphone	NULL	NULL	NULL	NULL
+select * from
+json_table(
+'[{"doc":[1,2]},{"doc":{"k":"v"}},{"doc":null},{}]',
+'$[*]' columns (doc json format json path '$.doc' null on empty)
+) as jt;
+doc
+[1,2]
+{"k":"v"}
+null
+NULL
+SELECT HEX(doc) FROM
+json_table(
+'[{"doc":[1,2]},{}]',
+'$[*]' columns (doc blob format json path '$.doc' null on empty)
+) as jt;
+HEX(doc)
+5B312C325D
+NULL
+select * from
+json_table(
+'[{"name":"Jeans","sizes":[32,34,36]},{"name":"Cellphone"}]',
+'$[*]' columns (name varchar(10) path '$.name',
+sizes varchar(100) format json path '$.sizes'
+               default '[99]' on empty)
+) as jt;
+name	sizes
+Jeans	[32,34,36]
+Cellphone	[99]
+select * from
+json_table(
+'[{"a":[1]},{"a":[2]}]',
+'$' columns (a varchar(20) format json path '$[*].a' error on error)
+) as jt;
+ERROR HY000: Can't store multiple matches of the path in the column 'a' of JSON_TABLE 'jt'.
+select * from
+json_table(
+'[{"a":[1,2,3]}]',
+'$[*]' columns (a int format json path '$.a')
+) as jt;
+ERROR HY000: Incorrect usage of FORMAT JSON and non-string JSON_TABLE column
+create view v_fmt as
+select * from
+json_table(
+'[{"sizes":[1,2]}]',
+'$[*]' columns (sizes varchar(20) format json path '$.sizes')
+) as jt;
+select * from v_fmt;
+sizes
+[1,2]
+show create view v_fmt;
+View	Create View	character_set_client	collation_connection
+v_fmt	CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v_fmt` AS select `jt`.`sizes` AS `sizes` from JSON_TABLE('[{"sizes":[1,2]}]', '$[*]' COLUMNS (`sizes` varchar(20) FORMAT JSON PATH '$.sizes')) `jt`	latin1	latin1_swedish_ci
+drop view v_fmt;
+create view v_fmt_cs as
+select * from
+json_table(
+'[{"sizes":[1,2]}]',
+'$[*]' columns (
+sizes varchar(20) character set utf8mb4 collate utf8mb4_bin
+format json path '$.sizes')
+) as jt;
+show create view v_fmt_cs;
+View	Create View	character_set_client	collation_connection
+v_fmt_cs	CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v_fmt_cs` AS select `jt`.`sizes` AS `sizes` from JSON_TABLE('[{"sizes":[1,2]}]', '$[*]' COLUMNS (`sizes` varchar(20) CHARSET utf8mb4 COLLATE utf8mb4_bin FORMAT JSON PATH '$.sizes')) `jt`	latin1	latin1_swedish_ci
+drop view v_fmt_cs;
+select * from
+json_table(
 '[{"a":"3"},{"a":2},{"b":1},{"a":0}]',
 '$[*]' columns (id for ordinality,
 jpath varchar(100) path '$.a' error on empty,
--- a/mysql-test/suite/json/t/json_table_mysql.test
+++ b/mysql-test/suite/json/t/json_table_mysql.test
@@ -84,6 +84,73 @@ select * from
 #eval $query;
 #eval explain  $query;

+select * from
+  json_table(
+    '[{"name":"Jeans","sizes":[32,34,36],"details":{"fit":"regular"},"flag":true,"jsnull":null},
+      {"name":"T-Shirt","sizes":["Medium","Large"],"details":{"fit":"loose"},"flag":false,"jsnull":null},
+      {"name":"Cellphone"}]',
+    '$[*]' columns (name varchar(10) path '$.name',
+             sizes varchar(100) format json path '$.sizes',
+             details text format json path '$.details',
+             flag varchar(10) format json path '$.flag',
+             jsnull varchar(10) format json path '$.jsnull')
+  ) as jt;
+
+select * from
+  json_table(
+    '[{"doc":[1,2]},{"doc":{"k":"v"}},{"doc":null},{}]',
+    '$[*]' columns (doc json format json path '$.doc' null on empty)
+  ) as jt;
+
+SELECT HEX(doc) FROM
+  json_table(
+    '[{"doc":[1,2]},{}]',
+    '$[*]' columns (doc blob format json path '$.doc' null on empty)
+  ) as jt;
+
+select * from
+  json_table(
+    '[{"name":"Jeans","sizes":[32,34,36]},{"name":"Cellphone"}]',
+    '$[*]' columns (name varchar(10) path '$.name',
+             sizes varchar(100) format json path '$.sizes'
+               default '[99]' on empty)
+  ) as jt;
+
+--error ER_JSON_TABLE_MULTIPLE_MATCHES
+select * from
+  json_table(
+    '[{"a":[1]},{"a":[2]}]',
+    '$' columns (a varchar(20) format json path '$[*].a' error on error)
+  ) as jt;
+
+--error ER_WRONG_USAGE
+select * from
+  json_table(
+    '[{"a":[1,2,3]}]',
+    '$[*]' columns (a int format json path '$.a')
+  ) as jt;
+
+create view v_fmt as
+select * from
+  json_table(
+    '[{"sizes":[1,2]}]',
+    '$[*]' columns (sizes varchar(20) format json path '$.sizes')
+  ) as jt;
+select * from v_fmt;
+show create view v_fmt;
+drop view v_fmt;
+
+create view v_fmt_cs as
+select * from
+  json_table(
+    '[{"sizes":[1,2]}]',
+    '$[*]' columns (
+      sizes varchar(20) character set utf8mb4 collate utf8mb4_bin
+        format json path '$.sizes')
+  ) as jt;
+show create view v_fmt_cs;
+drop view v_fmt_cs;
+
 --error ER_JSON_TABLE_ERROR_ON_FIELD
 select * from
  json_table(
--- a/sql/json_table.cc
+++ b/sql/json_table.cc
@@ -418,7 +418,7 @@ static void store_json_in_field(Field *f, const json_engine_t *je)
 }


-static int store_json_in_json(Field *f, json_engine_t *je)
+static int store_json_in_field_as_json(Field *f, json_engine_t *je)
 {
  const uchar *from= je->value_begin;
  const uchar *to;
@@ -617,7 +617,7 @@ int ha_json_table::fill_column_values(THD *thd, uchar * buf, uchar *pos)
          {
            if (jc->m_format_json)
            {
-              if (!(error= store_json_in_json(*f, &je)))
+              if (!(error= store_json_in_field_as_json(*f, &je)))
                error= er_handler.errors;
            }
            else if (!(error= !json_value_scalar(&je)))
@@ -931,6 +931,21 @@ TABLE *create_table_for_function(THD *thd, TABLE_LIST *sql_table)
 }


+bool Json_table_column::enable_format_json()
+{
+  if (!m_field->type_handler()->is_general_purpose_string_type())
+  {
+    my_error(ER_WRONG_USAGE, MYF(0), "FORMAT JSON",
+             "non-string JSON_TABLE column");
+    return true;
+  }
+
+  m_format_json= true;
+  m_explicit_format_json= true;
+  return false;
+}
+
+
 int Json_table_column::set(THD *thd, enum_type ctype, const LEX_CSTRING &path,
                           CHARSET_INFO *cs)
 {
@@ -955,8 +970,11 @@ int Json_table_column::set(THD *thd, enum_type ctype, const LEX_CSTRING &path,
  */
  m_path.s.c_str= (const uchar *) path.str;

-  if (ctype == PATH)
-    m_format_json= m_field->type_handler() == &type_handler_long_blob_json;
+  if (ctype == PATH &&
+      Type_handler_json_common::is_json_type_handler(m_field->type_handler()))
+  {
+    m_format_json= true;
+  }

  return 0;
 }
@@ -1018,10 +1036,13 @@ int Json_table_column::print(THD *thd, Field **f, String *str)
  {
    static const LEX_CSTRING path= { STRING_WITH_LEN(" PATH ") };
    static const LEX_CSTRING exists_path= { STRING_WITH_LEN(" EXISTS PATH ") };
+    bool is_json_type=
+      Type_handler_json_common::is_json_type_handler(m_field->type_handler());

    (*f)->sql_type(column_type);

-    if ((m_format_json ? str->append(STRING_WITH_LEN(" JSON ")) : str->append(column_type)))
+    if (is_json_type ? str->append(STRING_WITH_LEN("JSON")) :
+                       str->append(column_type))
      return 1;
    if (((*f)->has_charset() && m_explicit_cs &&
         (str->append(STRING_WITH_LEN(" CHARSET ")) ||
@@ -1029,6 +1050,8 @@ int Json_table_column::print(THD *thd, Field **f, String *str)
          (Charset(m_explicit_cs).can_have_collate_clause() &&
           (str->append(STRING_WITH_LEN(" COLLATE ")) ||
            str->append(&m_explicit_cs->coll_name))))) ||
+        (m_explicit_format_json &&
+         str->append(STRING_WITH_LEN(" FORMAT JSON"))) ||
        str->append(m_column_type == PATH ? &path : &exists_path) ||
        print_path(str, &m_path))
      return 1;
--- a/sql/json_table.h
+++ b/sql/json_table.h
@@ -151,6 +151,8 @@ public:

  enum_type m_column_type;
  bool m_format_json;
+  /* FORMAT JSON was explicitly specified and should be preserved. */
+  bool m_explicit_format_json;
  json_path_t m_path;
  On_response m_on_error;
  On_response m_on_empty;
@@ -165,12 +167,14 @@ public:
  int set(THD *thd, enum_type ctype, const LEX_CSTRING &path, CHARSET_INFO *cs);
  int set(THD *thd, enum_type ctype, const LEX_CSTRING &path,
          const Lex_column_charset_collation_attrs_st &cl);
+  bool enable_format_json();
  Json_table_column(Create_field *f, Json_table_nested_path *nest) :
    m_field(f), m_nest(nest), m_explicit_cs(NULL)
  {
    m_on_error.m_response= RESPONSE_NOT_SPECIFIED;
    m_on_empty.m_response= RESPONSE_NOT_SPECIFIED;
    m_format_json= false;
+    m_explicit_format_json= false;
  }
  int print(THD *tnd, Field **f, String *str);
 };
@@ -291,4 +295,3 @@ table_map add_table_function_dependencies(List<TABLE_LIST> *join_list,
                                          table_map nest_tables, bool *error);

 #endif /* JSON_TABLE_INCLUDED */
-
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -12323,6 +12323,20 @@ json_table_column_type:
              MYSQL_YYABORT;
            }
          }
+        | json_table_field_type FORMAT_SYM JSON_SYM PATH_SYM json_text_literal
+            json_opt_on_empty_or_error
+          {
+            if (Lex->last_field->set_attributes(thd, $1,
+                                                COLUMN_DEFINITION_TABLE_FIELD))
+              MYSQL_YYABORT;
+            if (Lex->json_table->m_cur_json_table_column->enable_format_json() ||
+                Lex->json_table->m_cur_json_table_column->
+                  set(thd, Json_table_column::PATH, $5,
+                      $1.charset_collation_attrs()))
+            {
+              MYSQL_YYABORT;
+            }
+          }
        | json_table_field_type EXISTS PATH_SYM json_text_literal
          {
            if (Lex->last_field->set_attributes(thd, $1,