MDEV-25381: JSON_TABLE: ER_WRONG_OUTER_JOIN upon query with LEFT and RIGHT joins and view

Table_function_json_table::m_dep_tables attempts to cache the value of
m_json->used_tables(), poorly. Remove the cache and use the value
directly.

Author: spetrunia

mysql-test/suite/json/r/json_table.result

@@ -750,5 +750,48 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	jt	ALL	NULL	NULL	NULL	NULL	40	Table function: json_table; Using where; FirstMatch(t1)
 drop table t1;
 #
+# MDEV-25381: JSON_TABLE: ER_WRONG_OUTER_JOIN upon query with LEFT and RIGHT joins and view
+#
+CREATE TABLE t1 (a INT);
+INSERT INTO t1 VALUES (1),(2);
+CREATE TABLE t2 (b INT, c TEXT);
+INSERT INTO t2 VALUES (1,'{}'),(2,'[]');
+CREATE VIEW v2 AS SELECT * FROM t2;
+SELECT *
+FROM
+t1 RIGHT JOIN
+t2 AS tt
+LEFT JOIN
+JSON_TABLE(tt.c, '$' COLUMNS(o FOR ORDINALITY)) AS jt
+ON tt.b = jt.o
+ON t1.a = tt.b;
+a	b	c	o
+1	1	{}	1
+2	2	[]	NULL
+SELECT *
+FROM
+t1 RIGHT JOIN
+v2 AS tt
+LEFT JOIN
+JSON_TABLE(tt.c, '$' COLUMNS(o FOR ORDINALITY)) AS jt
+ON tt.b = jt.o
+ON t1.a = tt.b;
+a	b	c	o
+1	1	{}	1
+2	2	[]	NULL
+SELECT *
+FROM
+t1 RIGHT JOIN
+v2 AS tt
+LEFT JOIN
+JSON_TABLE(CONCAT(tt.c,''), '$' COLUMNS(o FOR ORDINALITY)) AS jt
+ON tt.b = jt.o
+ON t1.a = tt.b;
+a	b	c	o
+1	1	{}	1
+2	2	[]	NULL
+DROP VIEW v2;
+DROP TABLE t1, t2;
+#
 # End of 10.6 tests
 #

mysql-test/suite/json/t/json_table.test

@@ -644,6 +644,47 @@ WHERE
 
 drop table t1;
 
+--echo #
+--echo # MDEV-25381: JSON_TABLE: ER_WRONG_OUTER_JOIN upon query with LEFT and RIGHT joins and view
+--echo #
+
+CREATE TABLE t1 (a INT);
+INSERT INTO t1 VALUES (1),(2);
+
+CREATE TABLE t2 (b INT, c TEXT);
+INSERT INTO t2 VALUES (1,'{}'),(2,'[]');
+CREATE VIEW v2 AS SELECT * FROM t2;
+
+SELECT *
+FROM
+  t1 RIGHT JOIN
+     t2 AS tt
+     LEFT JOIN
+     JSON_TABLE(tt.c, '$' COLUMNS(o FOR ORDINALITY)) AS jt
+     ON tt.b = jt.o
+  ON t1.a = tt.b;
+
+SELECT *
+FROM
+  t1 RIGHT JOIN
+    v2 AS tt
+    LEFT JOIN
+    JSON_TABLE(tt.c, '$' COLUMNS(o FOR ORDINALITY)) AS jt
+    ON tt.b = jt.o
+  ON t1.a = tt.b;
+
+SELECT *
+FROM
+  t1 RIGHT JOIN
+    v2 AS tt
+    LEFT JOIN
+    JSON_TABLE(CONCAT(tt.c,''), '$' COLUMNS(o FOR ORDINALITY)) AS jt
+    ON tt.b = jt.o
+ ON t1.a = tt.b;
+
+DROP VIEW v2;
+DROP TABLE t1, t2;
+
 --echo #
 --echo # End of 10.6 tests
 --echo #

sql/json_table.cc

@@ -1324,20 +1324,6 @@ int Table_function_json_table::setup(THD *thd, TABLE_LIST *sql_table,
       jc->m_field->charset= jc->m_explicit_cs;
     }
   }
-
-  m_dep_tables= m_json->used_tables();
-
-  if (m_dep_tables)
-  {
-    t->no_cache= TRUE;
-    if (unlikely(m_dep_tables & sql_table->get_map()))
-    {
-      /* Table itself is used in the argument. */
-      my_error(ER_WRONG_USAGE, MYF(0), "JSON_TABLE", "argument"); 
-      return TRUE;
-    }
-  }
-
   return FALSE;
 }
 
@@ -1475,12 +1461,8 @@ int Table_function_json_table::print(THD *thd, TABLE_LIST *sql_table,
 void Table_function_json_table::fix_after_pullout(TABLE_LIST *sql_table,
        st_select_lex *new_parent, bool merge)
 {
-  sql_table->dep_tables&= ~m_dep_tables;
-
   m_json->fix_after_pullout(new_parent, &m_json, merge);
-  m_dep_tables= m_json->used_tables();
-
-  sql_table->dep_tables|= m_dep_tables;
+  sql_table->dep_tables= used_tables();
 }
 
 

sql/json_table.h

@@ -208,8 +208,16 @@ class Table_function_json_table : public Sql_alloc
                          st_select_lex *new_parent, bool merge);
   void update_used_tables() { m_json->update_used_tables(); }
 
-  table_map used_tables() const { return m_dep_tables; }
-  bool join_cache_allowed() const { return !m_dep_tables; }
+  table_map used_tables() const { return m_json->used_tables(); }
+  bool join_cache_allowed() const
+  {
+    /*
+      Can use join cache when we have an outside reference.
+      If there's dependency on any other table or randomness,
+      cannot use it.
+    */
+    return !(used_tables() & ~OUTER_REF_TABLE_BIT);
+  }
   void get_estimates(ha_rows *out_rows,
                      double *scan_time, double *startup_cost);
 
@@ -242,13 +250,6 @@ class Table_function_json_table : public Sql_alloc
   /* Context to be used for resolving the first argument. */
   Name_resolution_context *m_context;
 
-  /*
-    the JSON argument can be taken from other tables.
-    We have to mark these tables as dependent so the
-    mask of these dependent tables is calculated in ::setup().
-  */
-  table_map m_dep_tables;
-
   /* Current NESTED PATH level being parsed */
   Json_table_nested_path *cur_parent;