MDEV-17613 MIN/MAX Optimization (Select tables optimized away) does not work

Current easy fix is not possible, because SELECT clones ha_partition
and then closes the clone which leads to unclosed transaction in
partitions we forcely prune out. We cound solve this by closing these
partitions (and release from transaction) in
change_partitions_to_open() at versioning conditions stage, but this
is problematic because table lock is acquired for each partition at
open stage and therefore must be released when we close partition
handler in change_partitions_to_open(). More details in MDEV-20376.

This should change after MDEV-20250 where mechanism of opening
partitions will be improved.

This reverts commit cdbac54d.

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

@@ -547,17 +547,6 @@ t1	CREATE TABLE `t1` (
 create or replace table t1 (f int) with system versioning partition by hash(f);
 insert delayed into t1 values (1);
 #
-# MDEV-17613 MIN/MAX Optimization (Select tables optimized away) does not work
-#
-create or replace table t1 (pk int primary key) with system versioning
-partition by system_time (
-partition p1 history,
-partition pn current);
-insert into t1 values (1), (2);
-explain select max(pk) from t1;
-id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
-#
 # MDEV-20068 History partition rotation is not done under LOCK TABLES
 #
 create or replace table t1 (x int) with system versioning partition by system_time limit 1

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

@@ -44,7 +44,7 @@ i
 6
 explain partitions select * from t1;
 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	
+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

mysql-test/suite/versioning/t/partition.test

@@ -497,27 +497,6 @@ create or replace table t1 (f int) with system versioning partition by hash(f);
 --error 0,ER_DELAYED_NOT_SUPPORTED
 insert delayed into t1 values (1);
 
---echo #
---echo # MDEV-17613 MIN/MAX Optimization (Select tables optimized away) does not work
---echo #
---disable_query_log
-set @saved_storage_engine= @@default_storage_engine;
-if ($MTR_COMBINATION_HEAP)
-{
-  # This case does not work with HEAP
-  set default_storage_engine= myisam;
-}
---enable_query_log
-create or replace table t1 (pk int primary key) with system versioning
-partition by system_time (
-  partition p1 history,
-  partition pn current);
-insert into t1 values (1), (2);
-explain select max(pk) from t1;
---disable_query_log
-set default_storage_engine= @saved_storage_engine;
---enable_query_log
-
 --echo #
 --echo # MDEV-20068 History partition rotation is not done under LOCK TABLES
 --echo #

sql/sql_select.cc

@@ -721,19 +721,6 @@ void vers_select_conds_t::print(String *str, enum_query_type query_type) const
   }
 }
 
-/**
-  Setup System Versioning conditions
-
-  Add WHERE condition according to FOR SYSTEM_TIME clause.
-
-  If the table is partitioned by SYSTEM_TIME and there is no FOR SYSTEM_TIME
-  clause, then select now-partition instead of modifying WHERE condition.
-
-  @retval
-    -1    on error
-  @retval
-    0     on success
-*/
 int SELECT_LEX::vers_setup_conds(THD *thd, TABLE_LIST *tables)
 {
   DBUG_ENTER("SELECT_LEX::vers_setup_cond");
@@ -801,13 +788,12 @@ int SELECT_LEX::vers_setup_conds(THD *thd, TABLE_LIST *tables)
     vers_select_conds_t &vers_conditions= table->vers_conditions;
 
 #ifdef WITH_PARTITION_STORAGE_ENGINE
-    Vers_part_info *vers_info;
-    if (table->table->part_info && (vers_info= table->table->part_info->vers_info))
-    {
-      if (table->partition_names)
+      /*
+        if the history is stored in partitions, then partitions
+        themselves are not versioned
+      */
+      if (table->partition_names && table->table->part_info->vers_info)
       {
-        /* If the history is stored in partitions, then partitions
-            themselves are not versioned. */
         if (vers_conditions.is_set())
         {
           my_error(ER_VERS_QUERY_IN_PARTITION, MYF(0), table->alias.str);
@@ -816,19 +802,6 @@ int SELECT_LEX::vers_setup_conds(THD *thd, TABLE_LIST *tables)
         else
           vers_conditions.init(SYSTEM_TIME_ALL);
       }
-      else if (!vers_conditions.is_set() &&
-               /* We cannot optimize REPLACE .. SELECT because it may need
-                  to call vers_set_hist_part() to update history. */
-               thd->lex->sql_command != SQLCOM_REPLACE_SELECT)
-      {
-        table->partition_names= newx List<String>;
-        String *s= newx String(vers_info->now_part->partition_name,
-                               system_charset_info);
-        table->partition_names->push_back(s);
-        table->table->file->change_partitions_to_open(table->partition_names);
-        vers_conditions.init(SYSTEM_TIME_ALL);
-      }
-    }
 #endif
 
     if (outer_table && !vers_conditions.is_set())
@@ -978,7 +951,6 @@ int SELECT_LEX::vers_setup_conds(THD *thd, TABLE_LIST *tables)
   DBUG_RETURN(0);
 #undef newx
 }
-#undef newx
 
 /*****************************************************************************
   Check fields, find best join, do the select and output fields.