MDEV-17333 Assertion in update_auto_increment() upon exotic LOAD

While `handler::next_insert_id` is restored on duplicate key errors
`part_share->next_auto_inc_val` is not restored which causes
discrepancy.

1 files changed, 15 insertions, 0 deletions

diff --git a/sql/ha_partition.h b/sql/ha_partition.h
index d795502600f..0c945e5b317 100644
--- a/sql/ha_partition.h
+++ b/sql/ha_partition.h
@@ -92,6 +92,7 @@ public:
   bool auto_inc_initialized;
   mysql_mutex_t auto_inc_mutex;                /**< protecting auto_inc val */
   ulonglong next_auto_inc_val;                 /**< first non reserved value */
+  ulonglong prev_auto_inc_val;                 /**< stored next_auto_inc_val */
   /**
     Hash of partition names. Initialized in the first ha_partition::open()
     for the table_share. After that it is read-only, i.e. no locking required.
@@ -103,6 +104,7 @@ public:
   Partition_share()
     : auto_inc_initialized(false),
     next_auto_inc_val(0),
+    prev_auto_inc_val(0),
     partition_name_hash_initialized(false),
     partition_names(NULL)
   {
@@ -371,6 +373,19 @@ private:
   MY_BITMAP m_locked_partitions;
   /** Stores shared auto_increment etc. */
   Partition_share *part_share;
+  /** Store and restore next_auto_inc_val over duplicate key errors. */
+  virtual void store_auto_increment()
+  {
+    DBUG_ASSERT(part_share);
+    part_share->prev_auto_inc_val= part_share->next_auto_inc_val;
+    handler::store_auto_increment();
+  }
+  virtual void restore_auto_increment()
+  {
+    DBUG_ASSERT(part_share);
+    part_share->next_auto_inc_val= part_share->prev_auto_inc_val;
+    handler::restore_auto_increment();
+  }
   /** Temporary storage for new partitions Handler_shares during ALTER */
   List<Parts_share_refs> m_new_partitions_share_refs;
   /** Sorted array of partition ids in descending order of number of rows. */