Fixed MDEV-306 / LP:1007967 - Assertion `table->file->stats.records > 0 || error' failed join_read_const_table on concurrent SELECT and DROP/ADD INDEX

sql/sql_table.cc:
  Added comment
storage/maria/ma_close.c:
  Don't store history if it's visible to all.
  This fixed the MDEV-306 bug
storage/maria/ma_delete_table.c:
  Removed old comment
  Delete history state for deleted tables
storage/maria/ma_info.c:
  More DBUG_PRINT
storage/maria/ma_open.c:
  More DBUG_PRINT

4 files changed, 11 insertions, 9 deletions

diff --git a/storage/maria/ma_close.c b/storage/maria/ma_close.c
index 973adf2b91e..d1b90dc826e 100644
--- a/storage/maria/ma_close.c
+++ b/storage/maria/ma_close.c
@@ -193,9 +193,10 @@ int maria_close(register MARIA_HA *info)
     else
       share_can_be_freed= TRUE;
 
-    if (share->state_history)
+    if (share->state_history && share->state_history->trid)
     {
       MARIA_STATE_HISTORY_CLOSED *history;
+      DBUG_PRINT("info", ("Storing state history"));
       /*
         Here we ignore the unlikely case that we don't have memory to
         store the state. In the worst case what happens is that any transaction
diff --git a/storage/maria/ma_delete_table.c b/storage/maria/ma_delete_table.c
index 9e91638fa27..09d5cde5ad0 100644
--- a/storage/maria/ma_delete_table.c
+++ b/storage/maria/ma_delete_table.c
@@ -38,14 +38,8 @@ int maria_delete_table(const char *name)
   /** @todo LOCK take X-lock on table */
   /*
     We need to know if this table is transactional.
-    When built with RAID support, we also need to determine if this table
-    makes use of the raid feature. If yes, we need to remove all raid
-    chunks. This is done with my_raid_delete(). Unfortunately it is
-    necessary to open the table just to check this. We use
-    'open_for_repair' to be able to open even a crashed table. If even
-    this open fails, we assume no raid configuration for this table
-    and try to remove the normal data file only. This may however
-    leave the raid chunks behind.
+    Unfortunately it is necessary to open the table just to check this. We use
+    'open_for_repair' to be able to open even a crashed table.
   */
   if (!(info= maria_open(name, O_RDONLY, HA_OPEN_FOR_REPAIR)))
   {
@@ -56,6 +50,8 @@ int maria_delete_table(const char *name)
     sync_dir= (info->s->now_transactional && !info->s->temporary &&
                !maria_in_recovery) ?
       MY_SYNC_DIR : 0;
+    /* Remove history for table */
+    _ma_reset_state(info);
     maria_close(info);
   }
 
diff --git a/storage/maria/ma_info.c b/storage/maria/ma_info.c
index 97b5b8b7f7b..341ea147785 100644
--- a/storage/maria/ma_info.c
+++ b/storage/maria/ma_info.c
@@ -42,6 +42,7 @@ int maria_status(MARIA_HA *info, register MARIA_INFO *x, uint flag)
   MY_STAT state;
   MARIA_SHARE *share= info->s;
   DBUG_ENTER("maria_status");
+  DBUG_PRINT("info", ("records: %lld", info->state->records));
 
   x->recpos= info->cur_row.lastpos;
   if (flag == HA_STATUS_POS)
diff --git a/storage/maria/ma_open.c b/storage/maria/ma_open.c
index a526c0d4276..5f90f61c786 100644
--- a/storage/maria/ma_open.c
+++ b/storage/maria/ma_open.c
@@ -866,6 +866,9 @@ MARIA_HA *maria_open(const char *name, int mode, uint open_flags)
           _ma_remove_not_visible_states(history->state_history, 0, 0);
         history->state_history= 0;
         (void) my_hash_delete(&maria_stored_state, (uchar*) history);
+        DBUG_PRINT("info", ("Reading state history.  trid: %lu  records: %lld",
+                            (ulong) share->state_history->trid,
+                            share->state_history->state.records));
       }
       else
       {
@@ -988,6 +991,7 @@ MARIA_HA *maria_open(const char *name, int mode, uint open_flags)
   mysql_mutex_unlock(&THR_LOCK_maria);
 
   m_info->open_flags= open_flags;
+  DBUG_PRINT("exit", ("table: %p  name: %s",m_info, name));
   DBUG_RETURN(m_info);
 
 err: