Some DML operations on tables having unique secondary keys cause scanning
in the secondary index, for instance to find potential unique key violations
in the seconday index. This scanning may involve GAP locking in the index.
As this locking happens also when applying replication events in high priority
applier threads, there is a probabality for lock conflicts between two wsrep
high priority threads.

This PR avoids lock conflicts of high priority wsrep threads, which do
secondary index scanning e.g. for duplicate key detection.

The actual fix is the patch in sql_class.cc:thd_need_ordering_with(), where
we allow relaxed GAP locking protocol between wsrep high priority threads.
wsrep high priority threads (replication appliers, replayers and TOI processors)
are ordered by the replication provider, and they will not need serializability
support gained by secondary index GAP locks.

PR contains also a mtr test, which exercises a scenario where two replication
applier threads have a false positive conflict in GAP of unique secondary index.
The conflicting local committing transaction has to replay, and the test verifies
also that the replaying phase will not conflict with the latter repllication applier.
Commit also contains new test scenario for galera.galera_UK_conflict.test,
where replayer starts applying after a slave applier thread, with later seqno,
has advanced to commit phase. The applier and replayer have false positive GAP
lock conflict on secondary unique index, and replayer should ignore this.
This test scenario caused crash with earlier version in this PR, and to fix this,
the secondary index uniquenes checking has been relaxed even further.

Now innodb trx_t structure has new member: bool wsrep_UK_scan, which is set to
true, when high priority thread is performing unique secondary index scanning.
The member trx_t::wsrep_UK_scan is defined inside WITH_WSREP directive, to make
it possible to prepare a MariaDB build where this additional trx_t member is
not present and is not used in the code base. trx->wsrep_UK_scan is set to true
only for the duration of function call for: lock_rec_lock() trx->wsrep_UK_scan
is used only in lock_rec_has_to_wait() function to relax the need to wait if
wsrep_UK_scan is set and conflicting transaction is also high priority.
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>

MDEV-24432 : galera.galera_fk_cascade_delete_debug MTR failed: query 'reap' failed: 1205: Lock wait timeout exceeded

Add wait_conditions to verify correct database state before
next operation.

Use debug_sync to force FTWRL to pause in correct state.

MDEV-12908 binlog_encryption.binlog_xa_recover, binlog.binlog_xa_recover failed in bb with extra checkpoint

The parameter innodb_idle_flush_pct that was introduced in
MariaDB Server 10.1.2 by MDEV-6932 has no effect ever since
the InnoDB changes from MySQL 5.7.9 were applied in
commit 2e814d47.

Let us declare the parameter as deprecated and having no effect.

It is unclear for how long the result has been broken, because
./mtr --big-test is not run regularly.

Added sending of metadata in response to preparing request for
the commands SQLCOM_SHOW_BINLOG_EVENTS, SQLCOM_SHOW_RELAYLOG_EVENTS

Introduced val_time_packed and val_datetime_packed  functions for Item_direct_ref
to make sure to get the value from the item it is referring to.

The issue for incorrect result was that the item was getting its value
from the temporary table rather than from the view.

For EITS collection min and max fields are allocated for each column
that is set in the read_set bitmap of a table. This allocation of min and max
fields happens inside alloc_statistics_for_table.

For a partitioned table ha_rnd_init is called inside the function
collect_statistics_for_table which sets the read_set bitmap for the columns
inside the partition expression. This happens only when there is a write lock
on the partitioned table.
But the allocation happens before this, so min and max fields are not allocated
for the columns involved in the partition expression.
This resulted in a crash, as the EITS statistics were collected but there was
no min and max field to store the value to.

The fix would be to call ha_rnd_init inside the function alloc_statistics_for_table
that would make sure that min and max fields are allocated for the columns
involved in the partition expression.

use USERNAME_CHAR_LENGTH and HOSTNAME_LENGTH for perfschema
USER and HOST columns

enable the encryption (and abort on failure) after printing --help,
not before

MDEV-18428 Memory: If transactional=0 is specified in CREATE TABLE, it is not possible to ALTER TABLE

* be strict in CREATE TABLE, just like in ALTER TABLE, because
  CREATE TABLE, just like ALTER TABLE, can be rolled back for any engine
* but don't auto-convert warnings into errors for engine warnings
  (handler::create) - this matches ALTER TABLE behavior
* and not when creating a default record, these errors are handled
  specially (and replaced with ER_INVALID_DEFAULT)
* always issue a Note when a non-unique key is truncated, because it's
  not a Warning that can be converted to an Error. Before this commit
  it was a Note for blobs and a Warning for all other data types.

otherwise ALTER TABLE can break replication

MDEV-18428 Memory: If transactional=0 is specified in CREATE TABLE, it is not possible to ALTER TABLE

fix "engine does not support TRANSACTIONAL=1" error message to
match user input

update mqh in struct user_conn after taking it from the cache

1. only call calc_sum_of_all_status() if a global
   SHOW_xxx_STATUS variable is to be returned
2. only lock LOCK_status when copying global_status_var,
   but not when iterating all threads

sql standard (2016) allows <collate clause> in two places in the
<column definition> - as a part of the <data type> or at the very end.

Let's do that too.

Side effect: in column/SP declaration `COLLATE cs_coll` automatically
implies `CHARACTER SET cs` (unless charset was specified explicitly).
See changes in sp-ucs2.result

Server part:
  kill_handlerton() was accessing thd->ha_data[] for some other thd,
  while it could be concurrently modified by its owner thd.

  protect thd->ha_data[] modifications with a mutex.
  require this mutex when accessing thd->ha_data[] from kill_handlerton.

InnoDB part:
  on close_connection, detach trx from thd before freeing the trx

This reverts the server part of the commit 775fccea
but keeps InnoDB part (which reverted MDEV-17092 5530a93f).

So after this both MDEV-23536 and MDEV-17092 are reverted,
and the original bug is resurrected.

		with wrong data type is added

  Inplace alter fails to report error when fts_doc_id column with
wrong data type is added.

prepare_inplace_alter_table_dict(): Should check whether the column
is fts_doc_id. It should be of bigint type, should accept non null
data type and it should be in capital letters.

A race condition may occur between the execution of transaction commit,
and an execution of a KILL statement that would attempt to abort that
transaction.

MDEV-17092 worked around this race condition by modifying InnoDB code.
After that issue was closed, Sergey Vojtovich pointed out that this
race condition would better be fixed above the storage engine layer:

If you look carefully into the above, you can conclude that
thd->free_connection() can be called concurrently with
KILL/thd->awake(). Which is the bug. And it is partially fixed in
THD::~THD(), that is destructor waits for KILL completion:

Fix: Add necessary mutex operations to THD::free_connection()
and move WSREP specific code also there. This ensures that no
one is using THD while we do free_connection(). These mutexes
will also ensures that there can't be concurrent KILL/THD::awake().

innobase_kill_query
  We can now remove usage of trx_sys_mutex introduced on MDEV-17092.

trx_t::free()
  Poison trx->state and trx->mysql_thd

This patch is validated with an RQG run similar to the one that
reproduced MDEV-17092.

The assertion failed in handler::ha_reset upon SELECT under
READ UNCOMMITTED from table with index on virtual column.

This was the debug-only failure, though the problem is mush wider:
* MY_BITMAP is a structure containing my_bitmap_map, the latter is a raw
 bitmap.
* read_set, write_set and vcol_set of TABLE are the pointers to MY_BITMAP
* The rest of MY_BITMAPs are stored in TABLE and TABLE_SHARE
* The pointers to the stored MY_BITMAPs, like orig_read_set etc, and
 sometimes all_set and tmp_set, are assigned to the pointers.
* Sometimes tmp_use_all_columns is used to substitute the raw bitmap
 directly with all_set.bitmap
* Sometimes even bitmaps are directly modified, like in
TABLE::update_virtual_field(): bitmap_clear_all(&tmp_set) is called.

The last three bullets in the list, when used together (which is mostly
always) make the program flow cumbersome and impossible to follow,
notwithstanding the errors they cause, like this MDEV-17556, where tmp_set
pointer was assigned to read_set, write_set and vcol_set, then its bitmap
was substituted with all_set.bitmap by dbug_tmp_use_all_columns() call,
and then bitmap_clear_all(&tmp_set) was applied to all this.

To untangle this knot, the rule should be applied:
* Never substitute bitmaps! This patch is about this.
 orig_*, all_set bitmaps are never substituted already.

This patch changes the following function prototypes:
* tmp_use_all_columns, dbug_tmp_use_all_columns
 to accept MY_BITMAP** and to return MY_BITMAP * instead of my_bitmap_map*
* tmp_restore_column_map, dbug_tmp_restore_column_maps to accept
 MY_BITMAP* instead of my_bitmap_map*

These functions now will substitute read_set/write_set/vcol_set directly,
and won't touch underlying bitmaps.

fixing windows build.

Problem:
=======
Upon deleting or updating a row in a parent table (with primary key), if
the child table has virtual column and an associated key with ON UPDATE
CASCADE/ON DELETE CASCADE, it will result in slave crash.

Analysis:
========
Tables which are related through foreign key require prelocking similar to
triggers. i.e If a table has triggers/foreign keys we should add all tables
and routines used by them to the prelocking set.  This prelocking happens
during 'open_and_lock_tables' call.  Each table being opened is checked for
foreign key references. If foreign key reference exists then the child
table is opened and it is linked to the table_list. Upon any modification
to  parent table its corresponding child tables are retried from table_list
and they are updated accordingly. This prelocking work fine on master.

On slave  prelocking works for following cases.
 - Statement/mixed based replication
 - In row based replication when trigger execution is enabled through
   'slave_run_triggers_for_rbr=YES/LOGGING/ENFORCE'

Otherwise it results in an assert/crash, as the parent table will not find
the corresponding child table and it will be NULL. Dereferencing NULL
pointer leads to slave server exit.

Fix:
===
Introduce a new 'slave_fk_event_map' flag similar to 'trg_event_map'. This
flag will ensure that when foreign key is enabled in row based replication
all the parent and child tables are prelocked, so that parent is able to
locate the child table.

Note: This issue is specific to slave, hence only slave needs to be
      upgraded.

Analysis: select into outfile creates files everytime with 666 permission,
regardsless if umask environment variables and umask settings on OS level.
It seems hardcoded.
Fix: change 0666 to 0644 which will let anybody consume the file but not
change it.

MDEV-19442 server_audit plugin doesn't consider proxy users in server_audit_excl_users/server_audit_incl_users.

Check the proxy user just as the connection user against the
incl_users_list and excl_users_list.