diff --git a/mysql-test/mysql-test-run.pl b/mysql-test/mysql-test-run.pl
index 635b1e8f7f9..33d9c7b4ee5 100755
--- a/mysql-test/mysql-test-run.pl
+++ b/mysql-test/mysql-test-run.pl
@@ -751,8 +751,7 @@ sub run_test_server ($$$) {
 
 	  # Repeat test $opt_repeat number of times
 	  my $repeat= $result->{repeat} || 1;
-	  # Don't repeat if test was skipped
-	  if ($repeat < $opt_repeat && $result->{'result'} ne 'MTR_RES_SKIPPED')
+	  if ($repeat < $opt_repeat)
 	  {
 	    $result->{retries}= 0;
 	    $result->{rep_failures}++ if $result->{failures};
diff --git a/mysql-test/r/count_distinct.result b/mysql-test/r/count_distinct.result
index d55a232c715..760b2710586 100644
--- a/mysql-test/r/count_distinct.result
+++ b/mysql-test/r/count_distinct.result
@@ -106,3 +106,28 @@ count(distinct user_id)
 17
 drop table t1;
 set @@tmp_table_size = default;
+create table t1 (
+a VARCHAR(1020),
+b int
+);
+insert into t1 values
+( 0 , 1 ),
+( 1 , 2 ),
+( 2 , 3 ),
+( 3 , 4 ),
+( 4 , 5 ),
+( 5 , 6 ),
+( 6 , 7 ),
+( 7 , 8 ),
+( 8 , 9 ),
+( 9 , 10 ),
+( 0 , 11 ),
+( 1 , 12 ),
+( 2 , 13 ),
+( 3 , 14 );
+set @@tmp_table_size=1024;
+select count(distinct a) from t1;
+count(distinct a)
+10
+drop table t1;
+set @@tmp_table_size = default;
diff --git a/mysql-test/r/log_tables-big.result b/mysql-test/r/log_tables-big.result
index 1e189a7726f..4435d6d2723 100644
--- a/mysql-test/r/log_tables-big.result
+++ b/mysql-test/r/log_tables-big.result
@@ -1,3 +1,4 @@
+set @log_output.saved = @@global.log_output;
 set @@global.log_output = 'TABLE';
 set session long_query_time=10;
 select get_lock('bug27638', 1);
@@ -7,25 +8,25 @@ set session long_query_time=1;
 select get_lock('bug27638', 2);
 get_lock('bug27638', 2)
 0
-select if (query_time >= '00:00:01', 'OK', 'WRONG') as qt, sql_text from mysql.slow_log
+select if (query_time >= '00:00:01', 'OK', concat('WRONG: ',query_time)) as qt, sql_text from mysql.slow_log
 where sql_text = 'select get_lock(\'bug27638\', 2)';
 qt	sql_text
 OK	select get_lock('bug27638', 2)
 select get_lock('bug27638', 60);
 get_lock('bug27638', 60)
 0
-select if (query_time >= '00:00:59', 'OK', 'WRONG') as qt, sql_text from mysql.slow_log
+select if (query_time >= '00:00:59', 'OK', concat('WRONG: ',query_time)) as qt, sql_text from mysql.slow_log
 where sql_text = 'select get_lock(\'bug27638\', 60)';
 qt	sql_text
 OK	select get_lock('bug27638', 60)
 select get_lock('bug27638', 101);
 get_lock('bug27638', 101)
 0
-select if (query_time >= '00:01:40', 'OK', 'WRONG') as qt, sql_text from mysql.slow_log
+select if (query_time >= '00:01:40', 'OK', concat('WRONG: ',query_time)) as qt, sql_text from mysql.slow_log
 where sql_text = 'select get_lock(\'bug27638\', 101)';
 qt	sql_text
 OK	select get_lock('bug27638', 101)
 select release_lock('bug27638');
 release_lock('bug27638')
 1
-set @@global.log_output=default;
+set @@global.log_output = @log_output.saved;
diff --git a/mysql-test/r/view.result b/mysql-test/r/view.result
index 1cff9f378f8..c9889d7190b 100644
--- a/mysql-test/r/view.result
+++ b/mysql-test/r/view.result
@@ -5627,9 +5627,6 @@ CREATE TABLE t3 (a INT);
 CREATE ALGORITHM = MERGE VIEW v1 AS SELECT t2.a FROM t3 AS t1, t3 AS t2;
 CREATE ALGORITHM = MERGE VIEW v2 AS SELECT * FROM v1;
 PREPARE stmt FROM 'REPLACE INTO v2 SELECT a FROM t3';
-EXECUTE stmt;
-ERROR HY000: Can not insert into join view 'test.v2' without fields list
-EXECUTE stmt;
 ERROR HY000: Can not insert into join view 'test.v2' without fields list
 drop view v1,v2;
 drop table t3;
diff --git a/mysql-test/t/count_distinct.test b/mysql-test/t/count_distinct.test
index a00574b6cba..86045e862e7 100644
--- a/mysql-test/t/count_distinct.test
+++ b/mysql-test/t/count_distinct.test
@@ -120,6 +120,35 @@ select count(distinct user_id) from t1;
 drop table t1;
 set @@tmp_table_size = default;
 
+#
+# MDEV-13457: Wrong result for aggregate function with distinct clause when the value for 
+# tmp_table_size is small
+#
+
+create table t1 (
+a VARCHAR(1020),
+b int
+);
+insert into t1 values
+( 0 , 1 ),
+( 1 , 2 ),
+( 2 , 3 ),
+( 3 , 4 ),
+( 4 , 5 ),
+( 5 , 6 ),
+( 6 , 7 ),
+( 7 , 8 ),
+( 8 , 9 ),
+( 9 , 10 ),
+( 0 , 11 ),
+( 1 , 12 ),
+( 2 , 13 ),
+( 3 , 14 );
+set @@tmp_table_size=1024;
+select count(distinct a) from t1;
+drop table t1;
+set @@tmp_table_size = default;
+
 #
 # End of 5.5 tests
 #
diff --git a/mysql-test/t/log_tables-big.test b/mysql-test/t/log_tables-big.test
index 8936a163d73..fa8810ecd3b 100644
--- a/mysql-test/t/log_tables-big.test
+++ b/mysql-test/t/log_tables-big.test
@@ -7,6 +7,7 @@
 # check that CSV engine was compiled in
 --source include/have_csv.inc
 
+set @log_output.saved = @@global.log_output;
 set @@global.log_output = 'TABLE';
 
 connect (con1,localhost,root,,);
@@ -21,13 +22,13 @@ select get_lock('bug27638', 1);
 connection con2;
 set session long_query_time=1;
 select get_lock('bug27638', 2);
-select if (query_time >= '00:00:01', 'OK', 'WRONG') as qt, sql_text from mysql.slow_log
+select if (query_time >= '00:00:01', 'OK', concat('WRONG: ',query_time)) as qt, sql_text from mysql.slow_log
        where sql_text = 'select get_lock(\'bug27638\', 2)';
 select get_lock('bug27638', 60);
-select if (query_time >= '00:00:59', 'OK', 'WRONG') as qt, sql_text from mysql.slow_log
+select if (query_time >= '00:00:59', 'OK', concat('WRONG: ',query_time)) as qt, sql_text from mysql.slow_log
        where sql_text = 'select get_lock(\'bug27638\', 60)';
 select get_lock('bug27638', 101);
-select if (query_time >= '00:01:40', 'OK', 'WRONG') as qt, sql_text from mysql.slow_log
+select if (query_time >= '00:01:40', 'OK', concat('WRONG: ',query_time)) as qt, sql_text from mysql.slow_log
        where sql_text = 'select get_lock(\'bug27638\', 101)';
 connection con1;
 select release_lock('bug27638');
@@ -36,4 +37,4 @@ connection default;
 disconnect con1;
 disconnect con2;
 
-set @@global.log_output=default;
+set @@global.log_output = @log_output.saved;
diff --git a/mysql-test/t/view.test b/mysql-test/t/view.test
index 89f9c744a5f..cbccbb5d656 100644
--- a/mysql-test/t/view.test
+++ b/mysql-test/t/view.test
@@ -5573,11 +5573,8 @@ drop table t1,t2,t3;
 CREATE TABLE t3 (a INT);
 CREATE ALGORITHM = MERGE VIEW v1 AS SELECT t2.a FROM t3 AS t1, t3 AS t2;
 CREATE ALGORITHM = MERGE VIEW v2 AS SELECT * FROM v1;
+--error ER_VIEW_NO_INSERT_FIELD_LIST
 PREPARE stmt FROM 'REPLACE INTO v2 SELECT a FROM t3';
---error ER_VIEW_NO_INSERT_FIELD_LIST
-EXECUTE stmt;
---error ER_VIEW_NO_INSERT_FIELD_LIST
-EXECUTE stmt;
 drop view v1,v2;
 drop table t3;
 
diff --git a/sql/sql_class.h b/sql/sql_class.h
index 6d2c9ef89fd..57ff65cb416 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -4617,7 +4617,7 @@ public:
   {
     DBUG_ENTER("unique_add");
     DBUG_PRINT("info", ("tree %u - %lu", tree.elements_in_tree, max_elements));
-    if (!(tree.flag & TREE_ONLY_DUPS) && 
+    if (!(tree.flag & TREE_ONLY_DUPS) &&
         tree.elements_in_tree >= max_elements && flush())
       DBUG_RETURN(1);
     DBUG_RETURN(!tree_insert(&tree, ptr, 0, tree.custom_arg));
diff --git a/sql/sql_derived.cc b/sql/sql_derived.cc
index 2ca97a32071..4578bcec394 100644
--- a/sql/sql_derived.cc
+++ b/sql/sql_derived.cc
@@ -520,6 +520,8 @@ bool mysql_derived_merge_for_insert(THD *thd, LEX *lex, TABLE_LIST *derived)
                       derived->merge_underlying_list != 0));
   if (derived->merged_for_insert)
     DBUG_RETURN(FALSE);
+  if (derived->init_derived(thd, FALSE))
+    DBUG_RETURN(TRUE);
   if (derived->is_materialized_derived())
     DBUG_RETURN(mysql_derived_prepare(thd, lex, derived));
   if ((thd->lex->sql_command == SQLCOM_UPDATE_MULTI ||
@@ -537,8 +539,6 @@ bool mysql_derived_merge_for_insert(THD *thd, LEX *lex, TABLE_LIST *derived)
       DBUG_ASSERT(derived->table);
     }
   }
-  else
-    derived->table= derived->merge_underlying_list->table;
   DBUG_RETURN(FALSE);
 }
 
diff --git a/sql/uniques.cc b/sql/uniques.cc
index 31c00667440..8dd028c93f5 100644
--- a/sql/uniques.cc
+++ b/sql/uniques.cc
@@ -100,6 +100,9 @@ Unique::Unique(qsort_cmp2 comp_func, void * comp_func_fixed_arg,
   */
   max_elements= (ulong) (max_in_memory_size /
                          ALIGN_SIZE(sizeof(TREE_ELEMENT)+size));
+  if (!max_elements)
+    max_elements= 1;
+
   (void) open_cached_file(&file, mysql_tmpdir,TEMP_PREFIX, DISK_BUFFER_SIZE,
                           MYF(MY_WME));
 }
@@ -643,11 +646,12 @@ bool Unique::walk(TABLE *table, tree_walk_action action, void *walk_action_arg)
   if (flush_io_cache(&file) || reinit_io_cache(&file, READ_CACHE, 0L, 0, 0))
     return 1;
   /*
-    merge_buffer must fit at least MERGEBUFF2 keys, because
-    merge_index() can merge that many BUFFPEKs at once.
+    merge_buffer must fit at least MERGEBUFF2 + 1 keys, because
+    merge_index() can merge that many BUFFPEKs at once. The extra space for one key 
+    is needed when a piece of merge buffer is re-read, see merge_walk()
   */
-  size_t buff_sz= MY_MAX(MERGEBUFF2, max_in_memory_size/full_size+1) * full_size;
-  if (!(merge_buffer = (uchar *)my_malloc(buff_sz, MYF(MY_THREAD_SPECIFIC|MY_WME))))
+  size_t buff_sz= MY_MAX(MERGEBUFF2+1, max_in_memory_size/full_size+1) * full_size;
+  if (!(merge_buffer = (uchar *)my_malloc(buff_sz, MYF(MY_WME))))
     return 1;
   if (buff_sz < full_size * (file_ptrs.elements + 1UL))
     res= merge(table, merge_buffer, buff_sz >= full_size * MERGEBUFF2) ;
@@ -708,8 +712,8 @@ bool Unique::merge(TABLE *table, uchar *buff, bool without_last_merge)
    full_size;
   sort_param.min_dupl_count= min_dupl_count;
   sort_param.res_length= 0;
-  sort_param.max_keys_per_buffer= 
-    (uint) (max_in_memory_size / sort_param.sort_length);
+  sort_param.keys= (uint) MY_MAX((max_in_memory_size / sort_param.sort_length),
+                                 MERGEBUFF2);
   sort_param.not_killable= 1;
 
   sort_param.unique_buff= buff +(sort_param.max_keys_per_buffer *