Print this piece when we've just made the choice to convert to semi-join.
Also, print it when we've already made that choice before:

  transformation": {
     "select_id": 2,
     "from": "IN (SELECT)",
     "to": "semijoin",
     "chosen": true
   }

Let us create and drop a separate database for getting rid of the
default database in the MDEV-22781 test.

The warning message says the file contains a character which can not be
represented in current codepage (not exactly accurate)

Disable lock elision, due to buggy intrin.h (_xbegin is misspelled)
Fix warnings.

restore the old behavior where without a debugger mtr does not
wait for mysqld to start. It was broken in feacc0aa

close_connections() in mysqld.cc sends a signal to all threads.
But InnoDB is too busy purging, doesn't react immediately.
close_connections() waits 20 seconds, which isn't enough in this
particular case, and then unlinks all threads from
the list and forcibly closes their vio connection.

InnoDB background  threads have no vio connection to close, but
they're unlinked all the same. So when later they finally notice
the shutdown request and try to unlink themselves, they fail to
assert that they're still linked.

Fix: don't assert_linked, as another thread can unlink this THD anytime

MDEV-20330 Combination of "," (comma), cross join and left join fails to parse

From 10.4.13, the `mariadb.sys` user was created to replace `root` definers.
 - In commit 0253ea7f, definer of
   Add/DropGeometryColumn procedures was changed to `mariadb.sys`, in
   `scripts/maria_add_gis_sp.sql.in`.
   However, maria_add_gis_sp.sql only applies to new databases created by
   installation script. Databases upgraded from old versions will miss this
   change.
 - In addition, according to commit
   0d6d801e(MDEV-23102), in some scenarios
   when root user is replaced it will skip creating `mariadb.sys` user.

This commit is to update the definer from `root` to `mariadb.sys` during
upgrade. It only makes the change if the original definers are root.

Doesn't choose to execute `maria_add_gis_sp.sql` in upgrade script to
recreate the procedures is because of considering the scenarios of
MDEV-23102 that `root` user is replaced and `mariadb.sys` is not created.

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.

Occasionally, the test would fail with a result difference for
ddl_log_file_alter_table (0 instead of 1) due to some
nondeterminism in the test. Let us remove that nondeterminism.

In commit 1193a793 we
set innodb_use_native_aio=OFF when using io_uring
on a kernel where write requests could potentially be lost.

The last reproducible issue was fixed in Linux 5.16-rc1
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.16-rc1&id=d3e3c102d107bb84251455a298cf475f24bab995
and the fix was backported to 5.15.3.

Hence, using a 5.16 or later kernel should be fine.
The Debian kernel 5.15.0-1-amd64 (5.15.3-1) was tested.
On Debian, utsname::release or uname -r does not reflect the
exact minor version while utsname::version and uname -v does.

On Fedora however the utsname::version is rather different:

  $ uname -r
  5.14.20-200.fc34.x86_64
  $ uname -v
  #1 SMP Thu Nov 18 22:03:20 UTC 2021

As such we use the version, but fall back to the release if
there isn't the beginnings of a kernel version in the version.

Thanks to Daniel Black for reporting the Linux kernel bug and
Jens Axboe for actually fixing it.
Co-Authored-By: Daniel Black <daniel@mariadb.org>

Closes: #1953

Fix a potential deadlock bug between locks ctrl_mutex and entry->mutex

Sys_lc_messages, Sys_lc_time_names: Use offsetof(MY_LOCALE, ...)
because the type has standard layout.

The macro my_offsetof() performs pointer arithmetics that may be
undefined behavior. As reported in MDEV-26272, it may cause
clang -fsanitize=undefined to generate invalid memory references.

struct PFS_events_statements: Convert to std::is_standard_layout
by encapsulating the standard-layout struct PFS_events instead of
deriving from it, so that the standard macro offsetof() can be used.

PFS_events_statements::copy(): Renamed from copy_events_statements().
A cast to void* is now needed in memcpy() to avoid GCC -Wclass-memaccess
"writing to an object ... leaves 64 bytes unchanged".

mdl_hash_function(): Use plain offsetof; MDL_key has standard layout.

There's no need for Debian to set config items to their
default. Left commented user, datadir and tmpdir as
these may want to be changed. lc-messages and skip-external-locks
are so infrequently set even listing them looks overly verbose.

socket left uncommented in [client-server] as various client
implementations may have different defaults compiled in.

MySQL documentation isn't going to help our
users and we shouldn't refer to it.

The bug occurs where the float token containing a dot with an 'e'
notation was dropped from the request completely.

This causes a manner of invalid SQL statements like:

select id 1.e, char 10.e(id 2.e), concat 3.e('a'12356.e,'b'1.e,'c'1.1234e)1.e, 12 1.e*2 1.e, 12 1.e/2 1.e, 12 1.e|2 1.e, 12 1.e^2 1.e, 12 1.e%2 1.e, 12 1.e&2 from test;

To be parsed correctly as if it was:

select id, char(id), concat('a','b','c'), 12*2, 12/2, 12|2, 12^2, 12%2, 12&2 from test.test;

This correct parsing occurs when e is followed by any of:

( ) . , | & % * ^ /

this patch moves cpack summury and description for optional packages
to the appropriate CMakeLists.txt files

Currently, SST scripts assume that the filename specified in
the --log-bin-index argument either does not contain an extension
or uses the standard ".index" extension. Similar assumptions are
used for the log_bin_index parameter read from the configuration
file. This commit adds support for arbitrary extensions for the
index file paths.

If the server is started with the --innodb-force-recovery argument
on the command line, then during SST this argument can be passed to
mariabackup only at the --prepare stage, and accordingly it must be
removed from the --mysqld-args list (and it is not should be passed
to mariabackup otherwise).

This commit fixes a flaw in the SST scripts and add a test that
checks the ability to run the joiner node in a configuration that
uses --innodb-force-recovery=1.

Currently, SST scripts assume that the filename specified in
the --log-bin-index argument either does not contain an extension
or uses the standard ".index" extension. Similar assumptions are
used for the log_bin_index parameter read from the configuration
file. This commit adds support for arbitrary extensions for the
index file paths.

If the server is started with the --innodb-force-recovery argument
on the command line, then during SST this argument can be passed to
mariabackup only at the --prepare stage, and accordingly it must be
removed from the --mysqld-args list (and it is not should be passed
to mariabackup otherwise).

This commit fixes a flaw in the SST scripts and add a test that
checks the ability to run the joiner node in a configuration that
uses --innodb-force-recovery=1.

This bug led to reporting bogus messages "No database selected" for DELETE
statements if they used subqueries in their WHERE conditions and these
subqueries contained references to CTEs.
The bug happened because the grammar rule for DELETE statement did not
call the function LEX::check_cte_dependencies_and_resolve_references() and
as a result of it references to CTEs were not identified as such.

Approved by Oleksandr Byelkin <sanja@mariadb.com>

This bug concerned only CREATE TABLE statements of the form
  CREATE TABLE <table name> AS <with clause> <union>.
For such a statement not all references to CTE used in <union> were resolved.
As a result a bogus message was reported for the first unresolved reference.
This happened because for such statements the function resolving references
to CTEs LEX::check_cte_dependencies_and_resolve_references() was called
prematurely in the parser.

Approved by Oleksandr Byelkin <sanja@mariadb.com>

buf_LRU_scan_and_free_block(): It turns out that even with
-fno-expensive-optimizations, GCC 4.8.5 may fail to split an instruction.
For the non-embedded server, -O1 would fail and -Og would seem to work,
while the embedded server build seems to require -O0.

buf_block_init(): Correct the MemorySanitizer instrumentation.

buf_page_get_low(): Do not read dirty data from read-fixed blocks.
These data races were identified by MemorySanitizer. If a read-fixed
block is being accessed, we must acquire and release a page latch,
so that the read-fix (and the exclusive page latch) will be released
and it will be safe to read the page frame contents if needed,
even before acquiring the final page latch. We do that in
buf_read_ahead_linear() and for the allow_ibuf_merge check.

mtr_t::page_lock(): Assert that the block is not read-fixed.

buf_page_get_low(): When we are creating an uncompressed page frame
for a ROW_FORMAT=COMPRESSED page, we must release the buf_pool.page_hash
latch and buf_pool.mutex while waiting for other threads to release their
fixes on the block.

This was caught by an occasional hang of the test innodb_zip.bug56680.