bugfix: partitioning and keyread on an indexed vcol

mysql-test/suite/vcol/r/partition.result

+CREATE TABLE t1 (
+id INT NOT NULL,
+store_id INT NOT NULL,
+x INT GENERATED ALWAYS AS (id + store_id)
+)
+PARTITION BY RANGE (store_id) (
+PARTITION p0 VALUES LESS THAN (6),
+PARTITION p1 VALUES LESS THAN (11),
+PARTITION p2 VALUES LESS THAN (16),
+PARTITION p3 VALUES LESS THAN (21)
+);
+INSERT t1 (id, store_id) VALUES(1, 2), (3, 4), (3, 12), (4, 18);
+CREATE INDEX idx ON t1(x);
+SELECT x FROM t1;
+x
+3
+7
+15
+22
+DROP TABLE t1;

mysql-test/suite/vcol/t/partition.test

+#
+# test keyread on an indexed vcol
+#
+--source include/have_partition.inc
+
+CREATE TABLE t1 (
+    id INT NOT NULL,
+    store_id INT NOT NULL,
+    x INT GENERATED ALWAYS AS (id + store_id)
+)
+PARTITION BY RANGE (store_id) (
+    PARTITION p0 VALUES LESS THAN (6),
+    PARTITION p1 VALUES LESS THAN (11),
+    PARTITION p2 VALUES LESS THAN (16),
+    PARTITION p3 VALUES LESS THAN (21)
+);
+INSERT t1 (id, store_id) VALUES(1, 2), (3, 4), (3, 12), (4, 18);
+CREATE INDEX idx ON t1(x);
+SELECT x FROM t1;
+DROP TABLE t1;

sql/ha_partition.cc

@@ -3434,7 +3434,7 @@ int ha_partition::open(const char *name, int mode, uint test_if_locked)
   }
   m_start_key.length= 0;
   m_rec0= table->record[0];
-  m_rec_length= table_share->stored_rec_length;
+  m_rec_length= table_share->reclength;
   if (!m_part_ids_sorted_by_num_of_records)
   {
     if (!(m_part_ids_sorted_by_num_of_records=