MDEV-18501 Partition pruning doesn't work for historical queries (fix)

Pruning fix for SYSTEM_TIME INTERVAL partitioning.

Allocating one more element in range_int_array for CURRENT partition
is required for RANGE pruning to work correctly
(get_partition_id_range_for_endpoint()).

mysql-test/suite/versioning/r/partition_rotation.result

@@ -47,7 +47,7 @@ id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	pn_pnsp0,pn_pnsp1	ALL	NULL	NULL	NULL	NULL	2	Using where
 explain partitions select * from t1 for system_time as of '2001-02-04 10:20:30';
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	p1_p1sp0,p1_p1sp1,p0_p0sp0,p0_p0sp1,p2_p2sp0,p2_p2sp1,pn_pnsp0,pn_pnsp1	ALL	NULL	NULL	NULL	NULL	#	Using where
+1	SIMPLE	t1	p0_p0sp0,p0_p0sp1,p2_p2sp0,p2_p2sp1,pn_pnsp0,pn_pnsp1	ALL	NULL	NULL	NULL	NULL	#	Using where
 set @ts=(select row_end from t1 for system_time all where i=1);
 select * from t1 for system_time all where row_end = @ts;
 i

sql/sql_lex.cc

@@ -8171,8 +8171,6 @@ bool LEX::part_values_current(THD *thd)
   elem->type= partition_element::CURRENT;
   DBUG_ASSERT(part_info->vers_info);
   part_info->vers_info->now_part= elem;
-  if (unlikely(part_info->init_column_part(thd)))
-    return true;
   return false;
 }
 
@@ -8203,8 +8201,6 @@ bool LEX::part_values_history(THD *thd)
     return true;
   }
   elem->type= partition_element::HISTORY;
-  if (unlikely(part_info->init_column_part(thd)))
-    return true;
   return false;
 }
 

sql/sql_partition.cc

@@ -1563,7 +1563,7 @@ static bool check_vers_constants(THD *thd, partition_info *part_info)
     return 0;
 
   part_info->range_int_array=
-    (longlong*) thd->alloc(hist_parts * sizeof(longlong));
+    (longlong*) thd->alloc(part_info->num_parts * sizeof(longlong));
 
   MYSQL_TIME ltime;
   List_iterator<partition_element> it(part_info->partitions);
@@ -1582,6 +1582,9 @@ static bool check_vers_constants(THD *thd, partition_info *part_info)
     if (vers_info->hist_part->range_value <= thd->query_start())
       vers_info->hist_part= el;
   }
+  DBUG_ASSERT(el == vers_info->now_part);
+  el->max_value= true;
+  part_info->range_int_array[el->id]= el->range_value= LONGLONG_MAX;
   return 0;
 err:
   my_error(ER_DATA_OUT_OF_RANGE, MYF(0), "TIMESTAMP", "INTERVAL");
@@ -7671,6 +7674,11 @@ static void set_up_range_analysis_info(partition_info *part_info)
     partitioning
   */
   switch (part_info->part_type) {
+  case VERSIONING_PARTITION:
+    if (!part_info->vers_info->interval.is_set())
+    {
+      break;
+    }
   case RANGE_PARTITION:
   case LIST_PARTITION:
     if (!part_info->column_list)
@@ -8107,7 +8115,8 @@ static int get_part_iter_for_interval_via_mapping(partition_info *part_info,
   part_iter->ret_null_part= part_iter->ret_null_part_orig= FALSE;
   part_iter->ret_default_part= part_iter->ret_default_part_orig= FALSE;
 
-  if (part_info->part_type == RANGE_PARTITION)
+  if (part_info->part_type == RANGE_PARTITION ||
+      part_info->part_type == VERSIONING_PARTITION)
   {
     if (part_info->part_charset_field_array)
       get_endpoint=        get_partition_id_range_for_endpoint_charset;