From 5392b4a32c9da296f7b2e6a5b83e3bff6c24871e Mon Sep 17 00:00:00 2001
From: Sergei Golubchik <serg@mariadb.org>
Date: Wed, 30 Oct 2019 19:31:26 +0100
Subject: MDEV-20354 All but last insert ignored in InnoDB tables when table
 locked

mysql_insert() first opens all affected tables (which implicitly
starts a transaction in InnoDB), then stat tables.
A failure to open a stat table caused open_tables() to abort
the current stmt transaction (trans_rollback_stmt()). So, from the
server point of view the following ha_write_row()-s happened outside
of a transactions, and the server didn't bother to commit them.

The server has a mechanism to prevent a transaction being
unexpectedly committed or rolled back in the middle of a statement -
if an operation takes place _in a sub-statement_ it cannot change
the transaction state. Operations on stat tables are exactly that -
they are not allowed to change a transaction state. Put them in
a sub-statement to make sure they don't.
---
 mysql-test/suite/innodb/r/stat_tables.result | 15 +++++++++++++++
 mysql-test/suite/innodb/t/stat_tables.test   | 17 +++++++++++++++++
 sql/sql_class.h                              |  4 ++++
 sql/sql_statistics.cc                        |  2 ++
 4 files changed, 38 insertions(+)
 create mode 100644 mysql-test/suite/innodb/r/stat_tables.result
 create mode 100644 mysql-test/suite/innodb/t/stat_tables.test

diff --git a/mysql-test/suite/innodb/r/stat_tables.result b/mysql-test/suite/innodb/r/stat_tables.result
new file mode 100644
index 00000000000..bb449570479
--- /dev/null
+++ b/mysql-test/suite/innodb/r/stat_tables.result
@@ -0,0 +1,15 @@
+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;
diff --git a/mysql-test/suite/innodb/t/stat_tables.test b/mysql-test/suite/innodb/t/stat_tables.test
new file mode 100644
index 00000000000..68344b3f425
--- /dev/null
+++ b/mysql-test/suite/innodb/t/stat_tables.test
@@ -0,0 +1,17 @@
+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;
diff --git a/sql/sql_class.h b/sql/sql_class.h
index 6c622648ac7..56bb9f45877 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -1444,12 +1444,16 @@ public:
 /**
   @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
diff --git a/sql/sql_statistics.cc b/sql/sql_statistics.cc
index 4a1ed9cde4e..f002a5a5eab 100644
--- a/sql/sql_statistics.cc
+++ b/sql/sql_statistics.cc
@@ -268,7 +268,9 @@ 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();
 
 
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