Problem:
========
- dict_stats_table_clone_create() does not initialize the
flag stats_error_printed in either dict_table_t or dict_index_t.
Because dict_stats_save_index_stat() is operating on a copy
of a dict_index_t object, it appears that
dict_index_t::stats_error_printed will always be false
for actual metadata objects, and uninitialized in
dict_stats_save_index_stat().
Solution:
=========
dict_stats_table_clone_create(): Assign stats_error_printed
for table and index while copying the statistics
Adding tests demonstrating that columns:
- mysql.innodb_table_stats.last_update
- mysql.innodb_index_stats.last_update
contain sane values close to NOW() rathar than a garbage.
Tests cover these three underlying TIMESTAMP data formats:
- MariaDB Field_timestamp0 - UINT4 based
Like in a MariaDB native installation running with mysql56_temporal_format=0
- MariaDB Field_timestampf - BINARY(4) based, with UNSIGNED_FLAG
Like in a MariaDB native installation running with mysql56_temporal_format=1
- MySQL-alike Field_timestampf - BINARY(4) based, without UNSIGNED_FLAG
Like with a MariaDB server running over a MySQL-5.6 directory
(e.g. during a migragion).
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.
