The fix broke mariabackup --prepare --incremental.

The restore of an incremental backup starts up (parts of) InnoDB twice.
First, all data files are discovered for applying .delta files. Then,
after the .delta files have been applied, InnoDB will be restarted
more completely, so that the redo log records will be applied via the
buffer pool.

During the first startup, the buffer pool is not initialized, and thus
trx_rseg_get_n_undo_tablespaces() must not be invoked. The apply of
the .delta files will currently assume that the --innodb-undo-tablespaces
option correctly specifies the number of undo tablespace files, just
like --backup does.

The second InnoDB startup of --prepare for applying the redo log will
properly invoke trx_rseg_get_n_undo_tablespaces().

enum srv_operation_mode: Add SRV_OPERATION_RESTORE_DELTA for
distinguishing the apply of .delta files from SRV_OPERATION_RESTORE.

srv_undo_tablespaces_init(): In mariabackup --prepare --incremental,
in the initial SRV_OPERATION_RESTORE_DELTA phase, do not invoke
trx_rseg_get_n_undo_tablespaces() because the buffer pool or the
redo logs are not available. Instead, blindly rely on the parameter
--innodb-undo-tablespaces.

If previous tests opened system tables, the test could fail because
it crashes the server. Added FLUSH TABLES to avoid it

fails with ERROR_INVALID_FUNCTION

This DeviceIoControl seems to happen on different boxes from time to time,
and there is not much user can do about it.
Instead of error, log a single INFO message, so it does not disturb users
much.

srv_undo_tablespaces_init(): In Mariabackup backup and restore modes,
do initialize the array of undo_tablespace_ids[].

MDEV-11240: Server crashes in check_view_single_update or Assertion `derived->table' failed in mysql_derived_merge_for_insert

Before "merge" view shoud be inited to maintaing transitive attributes like "multitable".

don't assume that the table always has a primary key,
head->s->primary_key might be MAX_KEY, which won't start keyread.

tabtyp was defined under ODBC_SUPPORT, but used
outside of it too (under JDBC_SUPPORT).

(socket connection ignores the port and CONNECT connects to the wrong host)

we'll copy it from 5.7 when we'll need it

Apply this patch from upstream:

commit 2c8deddfb67f1cd41ea3d1ac95aa1aa9327e3406
Author: Yoshinori Matsunobu <yoshinorim@users.noreply.github.com>
Date:   Tue Aug 15 16:21:58 2017 -0700

    Set exclusive_manual_compaction = false on manual compactions

    Summary:
    Combining exclusive manual compaction and
    non-exclusive manual compaction may hit rocksdb assertion errors.
    This diff makes all MyRocks internal manual compactions non exclusive.
    Closes https://github.com/facebook/mysql-5.6/pull/682

    Differential Revision: D5633619

    Pulled By: yoshinorim

    fbshipit-source-id: a90786d

The bug was caused by a defect of the patch for the bug 11081.
The patch was actually a port of the fix this bug from the mysql
code line. Later a correction of this fix was added to the
mysql code. Here's the comment this correction was provided with:

  Bug#16499751: Opening cursor on SELECT in stored procedure causes segfault
  This is a regression from the fix of bug#14740889.
  The fix started using another set of expressions as the source for
  the temporary table used for the materialized cursor. However,
  JOIN::make_tmp_tables_info() calls setup_copy_fields() which creates
  an Item_copy wrapper object on top of the function being selected.
  The Item_copy objects were not properly handled by create_tmp_table -
  they were simply ignored. This patch creates temporary table fields
  based on the underlying item of the Item_copy objects.

The test case for the bug 13346 was taken from mdev-13380.

The test mis-used MTR's "restart the server if it crashed or exited"
feature to try starting MyRocks plugin with invalid arguments.

Changed the test to use the --default-storage-engine=myisam which
allows the server to start when MyRocks fails to start.

This removes the need to "start the server with the arguments which
will caused it to fail to start", and so removes the race conditions
with MTR server restart code and  mysqld.*.expect file.

row_ins_check_foreign_constraint(): On timeout,
return DB_LOCK_WAIT_TIMEOUT instead of DB_LOCK_WAIT,
so that the lock wait will be properly terminated.
Also, replace some redundant assignments.

It looks like this bug was introduced in MySQL 5.7.8 by:

    commit a97f6b91227c7e0fc3151cfe5421891e79c12d19
    Author: Annamalai Gurusami <annamalai.gurusami@oracle.com>
    Date:   Tue Jun 9 16:02:31 2015 +0530

        Bug #20953265 INNODB: FAILING ASSERTION: RESULT != FTS_INVALID

MDEV-13498 is a performance regression that was introduced in MariaDB 10.2.2
by commit fec844ac
which introduced some Galera-specific conditions that were being
evaluated even if the write-set replication was not enabled.

MDEV-13246 Stale rows despite ON DELETE CASCADE constraint
is a correctness regression that was introduced by the same commit.

Especially the subcondition
	!(parent && que_node_get_type(parent) == QUE_NODE_UPDATE)
which is equivalent to
	!parent || que_node_get_type(parent) != QUE_NODE_UPDATE
makes little sense. If parent==NULL, the evaluation would proceed to the
std::find() expression, which would dereference parent. Because no SIGSEGV
was observed related to this, we can conclude that parent!=NULL always
holds. But then, the condition would be equivalent to
	que_node_get_type(parent) != QUE_NODE_UPDATE
which would not make sense either, because the std::find() expression
is actually assuming the opposite when casting parent to upd_node_t*.

It looks like this condition never worked properly, or that
it was never properly tested, or both.

wsrep_must_process_fk(): Helper function to check if FOREIGN KEY
constraints need to be processed. Only evaluate the costly std::find()
expression when write-set replication is enabled.

Also, rely on operator<<(std::ostream&, const id_name_t&) and
operator<<(std::ostream&, const table_name_t&) for pretty-printing
index and table names.

row_upd_sec_index_entry(): Add !wsrep_thd_is_BF() to the condition.
This is applying part of "Galera MW-369 FK fixes"
https://github.com/codership/mysql-wsrep/commit/f37b79c6dab101310a45a9e8cb23c0f98716da52
that is described by the following part of the commit comment:
    additionally: skipping wsrep_row_upd_check_foreign_constraint if thd has
    BF, essentially is applier or replaying
    This FK check would be needed only for populating parent row FK keys
    in write set, so no use for appliers

trx_set_rw_mode(): Check the flag high_level_read_only instead
of testing srv_force_recovery (innodb_force_recovery) directly.
There is no need to prevent the creation of read-write transactions
if innodb_force_recovery=3 is used. Yes, in that mode any recovered
incomplete transactions will not be rolled back, but these transactions
will continue to hold locks on the records that they have modified.
If the new read-write transactions hit conflicts with already existing
(possibly recovered) transactions, the lock wait timeout mechanism
will work just fine.

Install mtr and mysql-test-run symlinks in case of the out-of-source
build. This was broken in c872b100

Follow-up to original patch: fixing test cases.

Make test result stable

collateral changes:
* remove a test from innodb_virtual_basic that is already present in
  gcol_keys_innodb
* set thd->abort_on_warning for inplace alter, just like it's set
  for copy_data_between_tables - to have warnings converted into
  errors identically in all alter algorithms
* don't ignore errors in TABLE::update_virtual_field

don't allocate memory on thd->mem_root in every fix_fields(),
do it once and reuse.

doing SYSVAR_AUTOSIZE() because of back_log > max_connections
enabled "autosized" flag, and that made IS_SYSVAR_AUTOSIZE()
true, which triggered the second SYSVAR_AUTOSIZE.

Remove back_log <= max_connections limit, back_log
doesn't *always* have to be smaller than max_connections.

make JSON an alias for LONGTEXT CHARACTER SET utf8mb4 COLLATE utf8mb4_bin

(same collation that item_jsonfunc.cc is using internally)

SQL Standard behavior for DROP COLUMN xxx RESTRICT:
* If a constraint (UNIQUE or CHECK) uses only the dropped column,
  it's automatically dropped too. If it uses many columns - an error.

don't allow arbitrary combinations of SIGNED/UNSIGNED/ZEROFILL

let include/restart_mysqld.inc use include/start_mysqld.inc
and include/shutdown_mysqld.inc. Instead of copying their content.

InnoDB: in slow shutodwn mode do not stop purge threads
as long as some connection threads are running

execute queries after purge thread has exited, but the connection
thread hasn't

before c720e68f it used to crash

install all server includes under /usr/include/mysql/server/
and C/C includes under /usr/include/mysql/