MDEV-30334 Optimizer trace produces invalid JSON with WHERE subquery

Simple code rearrangement to stop it displaying an unsigned int in a String.

Author: mariadb-RexJohnston

mysql-test/main/opt_trace.result

@@ -10374,6 +10374,23 @@ exp1	exp2
 ]	1
 DROP TABLE t1;
 #
+# MDEV-30334 Optimizer trace produces invalid JSON with WHERE subquery
+#  Simple code rearrangement to stop it displaying an unsigned int in a String.
+#
+SET optimizer_trace= 'enabled=on';
+CREATE TABLE t1 (id INT PRIMARY KEY);
+INSERT INTO t1 VALUES (1),(2);
+CREATE TABLE t2 (a INT);
+INSERT INTO t2 VALUES (3),(4);
+SELECT * FROM t1 WHERE id < ( SELECT SUM(a) FROM t2 );
+id
+1
+2
+SELECT JSON_VALID(trace) FROM information_schema.optimizer_trace;
+JSON_VALID(trace)
+1
+DROP TABLE t1, t2;
+#
 # End of 10.4 tests
 #
 set optimizer_trace='enabled=on';

mysql-test/main/opt_trace.test

@@ -883,6 +883,23 @@ SELECT b, a FROM t1 WHERE b <> 'p' OR a = 4 GROUP BY b, a HAVING a <= 7; SELECT
 DROP TABLE t1;
 --enable_view_protocol
 
+--echo #
+--echo # MDEV-30334 Optimizer trace produces invalid JSON with WHERE subquery
+--echo #  Simple code rearrangement to stop it displaying an unsigned int in a String.
+--echo #
+
+SET optimizer_trace= 'enabled=on';
+
+CREATE TABLE t1 (id INT PRIMARY KEY);
+INSERT INTO t1 VALUES (1),(2);
+CREATE TABLE t2 (a INT);
+INSERT INTO t2 VALUES (3),(4);
+
+SELECT * FROM t1 WHERE id < ( SELECT SUM(a) FROM t2 );
+SELECT JSON_VALID(trace) FROM information_schema.optimizer_trace;
+
+DROP TABLE t1, t2;
+
 --echo #
 --echo # End of 10.4 tests
 --echo #

sql/sql_select.cc

@@ -30812,6 +30812,8 @@ void st_select_lex::print(THD *thd, String *str, enum_query_type query_type)
       }
     }
     str->append(STRING_WITH_LEN(" */ "));
+    if (join && join->cleaned) // if this join has been cleaned
+      return;                  // the select_number printed above is all we have
   }
 
   if (sel_type == SELECT_CMD ||
@@ -30826,10 +30828,11 @@ void st_select_lex::print(THD *thd, String *str, enum_query_type query_type)
       because temporary tables they pointed on could be freed.
     */
     str->append('#');
-    str->append(select_number);
+    str->append_ulonglong(select_number);
     return;
   }
 
+
   /* First add options */
   if (options & SELECT_STRAIGHT_JOIN)
     str->append(STRING_WITH_LEN("straight_join "));