Merge branch 'github/10.1' into 10.2

mysql-test/suite/innodb/r/stat_tables.result

+rename table mysql.table_stats to mysql.table_stats_save;
+flush tables;
+set use_stat_tables= PREFERABLY;
+create table t1 (a int) engine=InnoDB;
+start transaction;
+insert t1 values (1);
+insert t1 values (2);
+commit;
+select * from t1;
+a
+1
+2
+drop table t1;
+rename table mysql.table_stats_save to mysql.table_stats;
+flush tables;

mysql-test/suite/innodb/t/stat_tables.test

+source include/have_innodb.inc;
+
+#
+# MDEV-20354 All but last insert ignored in InnoDB tables when table locked
+#
+rename table mysql.table_stats to mysql.table_stats_save;
+flush tables;
+set use_stat_tables= PREFERABLY;
+create table t1 (a int) engine=InnoDB;
+start transaction;
+insert t1 values (1);
+insert t1 values (2);
+commit;
+select * from t1;
+drop table t1;
+rename table mysql.table_stats_save to mysql.table_stats;
+flush tables;

sql/sql_class.h

@@ -1579,12 +1579,16 @@ class Open_tables_backup: public Open_tables_state
 /**
   @class Sub_statement_state
   @brief Used to save context when executing a function or trigger
+
+  operations on stat tables aren't technically a sub-statement, but they are
+  similar in a sense that they cannot change the transaction status.
 */
 
 /* Defines used for Sub_statement_state::in_sub_stmt */
 
 #define SUB_STMT_TRIGGER 1
 #define SUB_STMT_FUNCTION 2
+#define SUB_STMT_STAT_TABLES 4
 
 
 class Sub_statement_state

sql/sql_statistics.cc

@@ -258,10 +258,8 @@ index_stat_def= {INDEX_STAT_N_FIELDS, index_stat_fields, 4, index_stat_pk_col};
   Open all statistical tables and lock them
 */
 
-static
-inline int open_stat_tables(THD *thd, TABLE_LIST *tables,
-                            Open_tables_backup *backup,
-                            bool for_write)
+static int open_stat_tables(THD *thd, TABLE_LIST *tables,
+                            Open_tables_backup *backup, bool for_write)
 {
   int rc;
 
@@ -269,12 +267,14 @@ inline int open_stat_tables(THD *thd, TABLE_LIST *tables,
   thd->push_internal_handler(&deh);
   init_table_list_for_stat_tables(tables, for_write);
   init_mdl_requests(tables);
+  thd->in_sub_stmt|= SUB_STMT_STAT_TABLES;
   rc= open_system_tables_for_read(thd, tables, backup);
+  thd->in_sub_stmt&= ~SUB_STMT_STAT_TABLES;
   thd->pop_internal_handler();
 
 
   /* If the number of tables changes, we should revise the check below. */
-  DBUG_ASSERT(STATISTICS_TABLES == 3);
+  compile_time_assert(STATISTICS_TABLES == 3);
 
   if (!rc &&
       (stat_table_intact.check(tables[TABLE_STAT].table, &table_stat_def) ||
@@ -3276,10 +3276,7 @@ int read_statistics_for_tables(THD *thd, TABLE_LIST *tables)
     DBUG_RETURN(0);
 
   if (open_stat_tables(thd, stat_tables, &open_tables_backup, FALSE))
-  {
-    thd->clear_error();
     DBUG_RETURN(1);
-  }
 
   for (TABLE_LIST *tl= tables; tl; tl= tl->next_global)
   {