MDEV-5037: Server crash on a JOIN on a derived table with join_cache_level > 2

- The crash was caused because the optimizer called handler->multi_range_read_info()
  on a derived temporary table.  That table has been created, but not opened yet.
  Because of that, handler::table was NULL, which caused crash.
  Fixed by changing DS-MRR methods to use handler::table_share instead. 
  handler::table_share is set in handler ctor, so this should be safe.

1 files changed, 11 insertions, 9 deletions

diff --git a/sql/multi_range_read.cc b/sql/multi_range_read.cc
index 1f624f4bc63..d9aeff21400 100644
--- a/sql/multi_range_read.cc
+++ b/sql/multi_range_read.cc
@@ -1494,10 +1494,10 @@ ha_rows DsMrr_impl::dsmrr_info_const(uint keyno, RANGE_SEQ_IF *seq,
   @retval FALSE  No
 */
 
-bool key_uses_partial_cols(TABLE *table, uint keyno)
+bool key_uses_partial_cols(TABLE_SHARE *share, uint keyno)
 {
-  KEY_PART_INFO *kp= table->key_info[keyno].key_part;
-  KEY_PART_INFO *kp_end= kp + table->key_info[keyno].key_parts;
+  KEY_PART_INFO *kp= share->key_info[keyno].key_part;
+  KEY_PART_INFO *kp_end= kp + share->key_info[keyno].key_parts;
   for (; kp != kp_end; kp++)
   {
     if (!kp->field->part_of_key.is_set(keyno))
@@ -1518,10 +1518,11 @@ bool key_uses_partial_cols(TABLE *table, uint keyno)
   @retval FALSE  Otherwise
 */
 
-bool DsMrr_impl::check_cpk_scan(THD *thd, uint keyno, uint mrr_flags)
+bool DsMrr_impl::check_cpk_scan(THD *thd, TABLE_SHARE *share, uint keyno, 
+                                uint mrr_flags)
 {
   return test((mrr_flags & HA_MRR_SINGLE_POINT) &&
-              keyno == table->s->primary_key && 
+              keyno == share->primary_key && 
               primary_file->primary_key_is_clustered() && 
               optimizer_flag(thd, OPTIMIZER_SWITCH_MRR_SORT_KEYS));
 }
@@ -1557,14 +1558,15 @@ bool DsMrr_impl::choose_mrr_impl(uint keyno, ha_rows rows, uint *flags,
   COST_VECT dsmrr_cost;
   bool res;
   THD *thd= current_thd;
+  TABLE_SHARE *share= primary_file->get_table_share();
 
-  bool doing_cpk_scan= check_cpk_scan(thd, keyno, *flags); 
-  bool using_cpk= test(keyno == table->s->primary_key &&
+  bool doing_cpk_scan= check_cpk_scan(thd, share, keyno, *flags); 
+  bool using_cpk= test(keyno == share->primary_key &&
                        primary_file->primary_key_is_clustered());
   *flags &= ~HA_MRR_IMPLEMENTATION_FLAGS;
   if (!optimizer_flag(thd, OPTIMIZER_SWITCH_MRR) ||
       *flags & HA_MRR_INDEX_ONLY ||
-      (using_cpk && !doing_cpk_scan) || key_uses_partial_cols(table, keyno))
+      (using_cpk && !doing_cpk_scan) || key_uses_partial_cols(share, keyno))
   {
     /* Use the default implementation */
     *flags |= HA_MRR_USE_DEFAULT_IMPL;
@@ -1572,7 +1574,7 @@ bool DsMrr_impl::choose_mrr_impl(uint keyno, ha_rows rows, uint *flags,
     return TRUE;
   }
 
-  uint add_len= table->key_info[keyno].key_length + primary_file->ref_length; 
+  uint add_len= share->key_info[keyno].key_length + primary_file->ref_length; 
   *bufsz -= add_len;
   if (get_disk_sweep_mrr_cost(keyno, rows, *flags, bufsz, &dsmrr_cost))
     return TRUE;