Bug #32617876: SIG11 IN SORT_PARAM::MAKE_SORTKEY|SQL/FILESORT.CC WITH HYPERGRAPH

If we have a sort by row ID, and we try to store a row from an
uninitialized temporary table (this can only happen if it is never
read, and below an outer join -- so we store a NULL-complemented row),
don't actually try to read the nonexistent row ID.

Change-Id: I75370600d64615a92753b410b63ab7447ba62501

Author: Steinar H. Gunderson

mysql-test/r/filesort.result

@@ -149,3 +149,27 @@ SELECT 1 AS a FROM t1 LEFT JOIN t2 ON FALSE GROUP BY a;
 a
 1
 DROP TABLE t1, t2;
+#
+# Bug #32617876: SIG11 IN SORT_PARAM::MAKE_SORTKEY|SQL/FILESORT.CC WITH HYPERGRAPH
+#
+CREATE TABLE t1 (
+a LONGBLOB,
+b INTEGER,
+c INTEGER
+);
+INSERT INTO t1 VALUES (NULL,1,3);
+INSERT INTO t1 VALUES (NULL,1,NULL);
+ANALYZE TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	analyze	status	OK
+SELECT *
+FROM t1
+LEFT JOIN (
+t1 AS t2 JOIN t1 AS t3 ON t2.c = t3.b
+JOIN ( SELECT DISTINCT b FROM t1 ) AS d1
+) ON TRUE
+ORDER BY t1.c;
+a	b	c	a	b	c	a	b	c	b
+NULL	1	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL
+NULL	1	3	NULL	NULL	NULL	NULL	NULL	NULL	NULL
+DROP TABLE t1;

mysql-test/t/filesort.test

@@ -137,3 +137,30 @@ INSERT INTO t1 VALUES ('a');
 CREATE TABLE t2 (a INTEGER PRIMARY KEY) PARTITION BY key() PARTITIONS 2;
 SELECT 1 AS a FROM t1 LEFT JOIN t2 ON FALSE GROUP BY a;
 DROP TABLE t1, t2;
+
+--echo #
+--echo # Bug #32617876: SIG11 IN SORT_PARAM::MAKE_SORTKEY|SQL/FILESORT.CC WITH HYPERGRAPH
+--echo #
+
+CREATE TABLE t1 (
+  a LONGBLOB,
+  b INTEGER,
+  c INTEGER
+);
+
+INSERT INTO t1 VALUES (NULL,1,3);
+INSERT INTO t1 VALUES (NULL,1,NULL);
+ANALYZE TABLE t1;
+
+# Set up a sort by row ID, where a temporary table (belonging to the
+# nonmergable derived table) has a NULL-complemented row, but never gets
+# properly initialized, and thus does not actually have a row ID.
+SELECT *
+FROM t1
+LEFT JOIN (
+  t1 AS t2 JOIN t1 AS t3 ON t2.c = t3.b
+  JOIN ( SELECT DISTINCT b FROM t1 ) AS d1
+) ON TRUE
+ORDER BY t1.c;
+
+DROP TABLE t1;

sql/filesort.cc

@@ -1544,7 +1544,13 @@ uint Sort_param::make_sortkey(Bounds_checked_array<uchar> dst,
       if (table->is_nullable()) {
         *to++ = table->has_null_row();
       }
-      memcpy(to, table->file->ref, table->file->ref_length);
+      if (table->is_nullable() && table->has_null_row()) {
+        // The contents are not used, but it's nice to have them
+        // defined when writing them to disk nevertheless.
+        memset(to, 0, table->file->ref_length);
+      } else {
+        memcpy(to, table->file->ref, table->file->ref_length);
+      }
       to += table->file->ref_length;
     }
   }