MDEV-17070 Table corruption or Assertion `table->file->stats.records > 0 || error' or Assertion `!is_set() || (m_status == DA_OK_BULK && is_bulk_op())' failed upon actions on temporary table

This was caused by a combination of factors:
* MyISAM/Aria temporary tables historically never saved the state
  to disk (MYI/MAI), because the state never needed to persist
* certain ALTER TABLE operations modify the original TABLE structure
  and if they fail, the original table has to be reopened to
  revert all changes (m_needs_reopen=1)

as a result, when ALTER fails and MyISAM/Aria temp table gets reopened,
it reads the stale state from the disk.

As a fix, MyISAM/Aria tables now *always* write the state to disk
on close, *unless* HA_EXTRA_PREPARE_FOR_DROP was done first. And
the server now always does HA_EXTRA_PREPARE_FOR_DROP before dropping
a temporary table.

1 files changed, 5 insertions, 6 deletions

diff --git a/sql/temporary_tables.cc b/sql/temporary_tables.cc
index 29c9910f332..ed23dae06d2 100644
--- a/sql/temporary_tables.cc
+++ b/sql/temporary_tables.cc
@@ -491,6 +491,7 @@ bool THD::close_temporary_tables()
     /* Traverse the table list. */
     while ((table= share->all_tmp_tables.pop_front()))
     {
+      table->file->extra(HA_EXTRA_PREPARE_FOR_DROP);
       free_temporary_table(table);
     }
   }
@@ -579,9 +580,7 @@ bool THD::rename_temporary_table(TABLE *table,
   @return false                       Table was dropped
           true                        Error
 */
-bool THD::drop_temporary_table(TABLE *table,
-                               bool *is_trans,
-                               bool delete_table)
+bool THD::drop_temporary_table(TABLE *table, bool *is_trans, bool delete_table)
 {
   DBUG_ENTER("THD::drop_temporary_table");
 
@@ -624,7 +623,8 @@ bool THD::drop_temporary_table(TABLE *table,
       parallel replication
     */
     tab->in_use= this;
-
+    if (delete_table)
+      tab->file->extra(HA_EXTRA_PREPARE_FOR_DROP);
     free_temporary_table(tab);
   }
 
@@ -1419,8 +1419,7 @@ bool THD::log_events_and_free_tmp_shares()
 
   @return void
 */
-void THD::free_tmp_table_share(TMP_TABLE_SHARE *share,
-                               bool delete_table)
+void THD::free_tmp_table_share(TMP_TABLE_SHARE *share, bool delete_table)
 {
   DBUG_ENTER("THD::free_tmp_table_share");