Adding debug output for key and keyseg flags at ha_myisam::open() time.
So now there are three points of debug output:

1. In the very end of mysql_prepare_create_table()
2. In ha_myisam::create(), after the table2myisam() call
3. In ha_myisan::open(), after the mi_open() call

mi_create(), which is is called between 2 and 3, modifies flags for
some data types, so the output in 2 and 3 is different.

MDEV-29707 : Incorrect/bad errno on enabling wsrep_on after setting dummy wsrep_provider on non-Galera build

Fix error message to contain correct errno. This commit was
tested interactively because mtr will notice if you provide
wrong wsrep_provider in config and you may not change
wsrep_provider dynamically.

MDEV-25389 : Assertion `!is_thread_specific || (mysqld_server_initialized && thd)' failed in void my_malloc_size_cb_func(long long int, my_bool)

If wsrep slave thread creation fails for some reason we need to handle
this error correctly and set actual running slave threads accordingly.

MDEV-26597 : Assertion `!wsrep_has_changes(thd) || (thd->lex->sql_command == SQLCOM_CREATE_TABLE && !thd->is_current_stmt_binlog_format_row())' failed.

If repl.max_ws_size is set too low following CREATE TABLE could fail
during commit. In this case wsrep_commit_empty should allow rolling
it back if provider state is s_aborted.

Furhermore, original ER_ERROR_DURING_COMMIT does not really tell anything
clear for user. Therefore, this commit adds a new error
ER_TOO_BIG_WRITESET. This will change some test cases output.

MDEV-27123 : auto_increment_increment and auto_increment_offset reset to 1 in current session after alter table on auto-increment column

Problem was that in ALTER TABLE execution variables were set
to 1 even when wsrep_auto_increment_control is OFF. We should
set them only when wsrep_auto_increment_control is ON.

In test user has set WSREP_ON=OFF this causes streaming replication
recovery to fail and this caused call to unireg_abort(). However,
this call is not necessary and we can let transaction to fail. Naturally,
if real user does this he needs to bootstrap his cluster.

This message would always have been invoked on ptr=NULL.

This test is not slow, but it reliably produces an EXPLAIN difference
(number of rows) on the Valgrind builder. A possible explanation could be
that the purge threads are not being scheduled. Valgrind runs all threads
in a single thread.

           upon CREATE OR REPLACE causing ER_UPDATE_TABLE_USED

Missed set return status to 1.

When f.ex. table is partitioned by HASH(a) and we rename column `a' to
`b' partitioning filter stays unchanged: HASH(a). That's the wrong
behavior.

The patch updates partitioning filter in accordance to the new columns
names. That includes partition/subpartition expression and
partition/subpartition field list.

For "const char *" replace() and after() accepted const as "T *" and
passed forward "void *". This cannot be cast implicitly, so we better
use "const void *" instead of "void *" in the input interface. This
way we avoid problems with using List for any const type.

MDEV-27927 row_sel_try_search_shortcut_for_mysql() does not latch a page, violating read view isolation

btr_search_guess_on_hash() would only acquire an index page latch if it
is invoked with ahi_latch=NULL. If it's invoked from
row_sel_try_search_shortcut_for_mysql() with ahi_latch!=NULL, a page
will not be latched, and row_search_mvcc() will get a pointer to the
record, which can be changed by some other transaction before the record
was stored in result buffer with row_sel_store_mysql_rec() call.

ahi_latch argument of btr_cur_search_to_nth_level_func() and
btr_pcur_open_with_no_init_func() is used only for
row_sel_try_search_shortcut_for_mysql().
btr_cur_search_to_nth_level_func(..., ahi_latch !=0, ...) is invoked
only from btr_pcur_open_with_no_init_func(..., ahi_latch !=0, ...),
which, in turns, is invoked only from
row_sel_try_search_shortcut_for_mysql().

I suppose that separate case with ahi_latch!=0 was intentionally
implemented to protect row_sel_store_mysql_rec() call in
row_search_mvcc() just after row_sel_try_search_shortcut_for_mysql()
call. After the ahi_latch was moved from row_seach_mvcc() to
row_sel_try_search_shortcut_for_mysql(), there is no need in it at all
if btr_search_guess_on_hash() latches a page unconditionally. And if
btr_search_guess_on_hash() latched the page, any access to the record in
row_sel_try_search_shortcut_for_mysql() after btr_pcur_open_with_no_init()
call will be protected with the page latch.

The fix is to remove ahi_latch argument from
btr_pcur_open_with_no_init_func(), btr_cur_search_to_nth_level_func()
and btr_search_guess_on_hash().

There will not be test, as to test it we need to freeze some SELECT
execution in the point between row_sel_try_search_shortcut_for_mysql()
and row_sel_store_mysql_rec() calls in row_search_mvcc(), and to change
the record in some other transaction to let row_sel_store_mysql_rec() to
store changed record in result buffer. Buf we can't do this with the
fix, as the page will be latched in btr_search_guess_on_hash() call.

Let us disable Valgrind on tests that would fail because a
server shutdown or a STOP SLAVE command would take longer,
causing the test harness to forcibly and silently kill the server
due to an exceeded timeout.

Under Valgrind, this test may occasionally fail because the sleep-based
timeouts of less than 1 second could be exceeded.

The test could emit some I/O error when run under Valgrind.

This fixes up commit 77c184df
which explicitly specifies that we use ISO/IEC 9899:1999 (C99),
which includes the snprintf() function.

row_purge_get_partial(): Replaces trx_undo_rec_get_partial_row().
Also copy the purge_node_t::ref to the purge_node_t::row.
In this way, the clustered index key fields will always be
available, even if thanks to
commit d384ead0 (MDEV-14799)
they would no longer be repeated in the remaining part of the
undo log record.

This commit adds automation that will reduce the possibility
of user errors when customizing wsrep_notify.sh (in particular
caused by user-specified parameters). Now all leading and trailing
spaces are removed from the user-specified parameters and automatic
port and host address substitution has been added to scripts, as
well as automatic password substitution to the client command line,
only if it is specified in the wsrep_notify.sh and not as empty
strings. Also added support for automatic substitution of the all
SSL-related parameters and improved parsing for ipv6 addresses
(to allow "[...]" notation for ipv6 addresses). Also added a
test to check if the wsrep notify script will works with SSL.

One can run these with --valgrind --big

MDEV-29575 Access to innodb_trx, innodb_locks and innodb_lock_waits along with detached XA's can cause SIGSEGV

trx->mysql_thd can be zeroed-out between thd_get_thread_id() and
thd_query_safe() calls in fill_trx_row(). trx_disconnect_prepared() zeroes out
trx->mysql_thd. And this can cause null pointer dereferencing in
fill_trx_row().

fill_trx_row() is invoked from fetch_data_into_cache() under trx_sys.mutex.

Bug fix is in reseting trx_t::mysql_thd in trx_disconnect_prepared() under
trx_sys.mutex lock too.

MTR test case can't be created for the fix, as we need to wait for
trx_t::mysql_thd reseting in fill_trx_row() after trx_t::mysql_thd was
checked for null while trx_sys.mutex is held. But trx_t::mysql_thd must be
reset in trx_disconnect_prepared() under trx_sys.mutex. There will be deadlock.

extended initializers are only allowed since c++11

Backporting from 10.5 to 10.4

This is needed to fix MDEV-28727 easier.

MDEV-17124: mariadb 10.1.34, views and prepared statements:  ERROR 1615 (HY000): Prepared statement needs to be re-prepared

The problem is that if table definition cache (TDC) is full of real tables
which are in tables cache, view definition can not stay there so will be
removed by its own underlying tables.
In situation above old mechanism of detection matching definition in PS
and current version always require reprepare and so prevent executing
the PS.

One work around is to increase TDC, other - improve version check for
views/triggers (which is done here). Now in suspicious cases we check:
 - timestamp (microseconds) of the view to be sure that version really
   have changed;
 - time (microseconds) of creation of a trigger related to time
   (microseconds) of statement preparation.

- Added missing information about database of corresponding table for various types of commands
- Update some typos

- Reviewed by: <vicentiu@mariadb.org>

KILL QUERY ID 0 was sometimes finding con3 that was still in the process
of disconnecting and had query_id==0 (as it didn't run any queries)

This patch resolves the problem of improper name resolution of table
references to embedded CTEs for some queries. This improper binding could
lead to
  - infinite sequence of calls of recursive functions
  - crashes due to resolution of null pointers
  - wrong result sets returned by queries
  - bogus error messages

If the definition of a CTE contains with clauses then such CTE is called
embedding CTE while CTEs from the with clauses are called embedded CTEs.
If a table reference used in the definition of an embedded CTE cannot be
resolved within the unit that contains this reference it still may be
resolved against a CTE definition from the with clause with one of the
embedding CTEs.
A table reference can be resolved against a CTE definition if it used in
the the scope of this definition and it refers to the name of the CTE.
Table reference t is in the scope of the CTE definition of CTE cte if
- the definition of cte is an element of a with clause declared as
  RECURSIVE and the reference t belongs either to the unit to which
  this with clause is attached or to one of the elements of this clause
- the definition of cte is an element of a with clause without RECURSIVE
  specifier and the reference t belongs either to the unit to which this
  with clause is attached or to one of the elements from this clause that
  are placed before the definition of cte.
If a table reference can be resolved against several CTE definitions then
it is bound to the most embedded.

The code before this patch not always resolved table references used in
embedded CTE according to the above rules.

Approved by Oleksandr Byelkin <sanja@mariadb.com>

Continue with similar changes as done in 19af1890 to replace sprintf(buf, ...)
with snprintf(buf, sizeof(buf), ...), specifically in the "easy" cases where buf
is allocated with a size known at compile time.

All new code of the whole pull request, including one or several files that are
either new files or modified ones, are contributed under the BSD-new license.  I
am contributing on behalf of my employer Amazon Web Services, Inc.