Pushing down statements to FederatedX engine is implemented by
printing either SELECT_LEX or SELECT_LEX_UNIT into a string and
sending that string to the engine. In the case of pushing down a
single SELECT having a CTE (WITH clause) there was a problem, because
normally single SELECTs were printed using SELECT_LEX::print().
But CTEs are stored in the upper unit of the SELECT_LEX -
SELECT_LEX_UNIT, so they were not unfolded in the string produced.

The solution is to invoke SELECT_LEX_UNIT::print() when pushing down
single SELECT statements (but not those which are parts of units),
so the possible CTEs are unfolded and printed.

Reviewed by Sergei Petrunia (sergey@mariadb.com)

In MemorySanitizer builds of 10.10 and 10.11, we would rather often
have the assertion fail in innodb_init() during mariadb-backup --prepare.
The assertion could also fail during InnoDB startup, but less often.

Before commit 685d958e in 10.8 the
log file cleanup after a successfully applied backup is different,
and the os_aio_pending_writes() assertion is in srv0start.cc.

IORequest::write_complete(): Invoke node->complete_write() before
releasing the page latch, so that a log checkpoint that is about to
execute concurrently will not miss a fdatasync() or fsync() on the
file, in case this was the first write since the last such call.

create_log_file(), srv_start(): Replace the debug assertion with
a debug check. For all intents and purposes, all writes could have
been completed but some write_io_callback() may not have invoked
io_slots::release() yet.

This was introduced in last merge with 10.6
The reason is that 10.6 does not need anything special to free histograms
as everything is allocated on a memroot.
In 10.10 histograms is using the vector class, which has some problems:
- No automatic free
- No memory usage accounting
(we should at some point remove vector usage because of the above problem)

Fixed by expliciting freeing histograms when freeing TABLE_STATISTICS
objects.

- Remove some references to dead macros

It was disabled in the recent 10.6->10.10 merge.

- InnoDB fails to check the overflow buffer while applying
the operation to the table that was rebuilt. This is caused
by commit 3cef4f8f (MDEV-515).

Fixed missing initialization of Alter_info()

This could cause crashes in some create table like scenarios
where some generated indexes where automatically dropped.

I also added a test that we do not try to drop from index_stats for
temporary tables.

The intentention was always to not create histograms for single value
unique keys (as histograms is not useful in this case), but because of
a bug in the code this was still done.

The changes in the test cases was mainly because hist_size is now NULL
for these kind of columns.

The MDEV-29693 conflict resolution is from Monty, as well as is
a bug fix where ANALYZE TABLE wrongly built histograms for
single-column PRIMARY KEY.
Also includes a fix for safe_malloc error reporting.

Other things:
- Copied main.log_slow from 10.4 to avoid mtr issue

Disabled test:
- spider/bugfix.mdev_27239 because we started to get
  +Error	1429 Unable to connect to foreign data source: localhost
  -Error	1158 Got an error reading communication packets
- main.delayed
  - Bug#54332 Deadlock with two connections doing LOCK TABLE+INSERT DELAYED
    This part is disabled for now as it fails randomly with different
    warnings/errors (no corruption).

MDEV-32272 lock_release_on_prepare_try() does not release lock if supremum bit is set along with other bits set in lock's bitmap

The error is caused by MDEV-30165 fix with the following commit:
d13a57ae

There is logical error in lock_release_on_prepare_try():

        if (supremum_bit)
          lock_rec_unlock_supremum(*cell, lock);
        else
          lock_rec_dequeue_from_page(lock, false);

Because there can be other bits set in the lock's bitmap, and the lock
type can be suitable for releasing criteria, but the above logic
releases only supremum bit of the lock.

The fix is to release lock if it suits for releasing criteria and unlock
supremum if supremum is locked otherwise.

Tere is also the test for the case, which was reported by QA team. I
placed it in a separate files, because it requires debug build.

Reviewed by: Marko Mäkelä

MDEV-31098  InnoDB Recovery doesn't display encryption message when no encryption configuration passed

- InnoDB fails to report the error when encryption configuration
wasn't passed. This patch addresses the issue by adding
the error while loading the tablespace and deferring the
tablespace creation.

There are many filesystem related errors that can occur with
MariaBackup. These already outputed to stderr with a good description of
the error. Many of these are permission or resource (file descriptor)
limits where the assertion and resulting core crash doesn't offer
developers anything more than the log message. To the user, assertions
and core crashes come across as poor error handling.

As such we return an error and handle this all the way up the stack.

log_t::create(), log_t::attach(): Return whether the initialisation
succeeded. It may fail if too large an innodb_log_buffer_size is specified.

recv_sys_t::close_files(): Actually close the data files so that the
test mariabackup.huge_lsn,strict_crc32 will not fail on Microsoft Windows
when renaming ib_logfile101 due to a leaked file handle of ib_logfile0.

recv_sys_t::find_checkpoint(): Register recv_sys.files[0] as OS_FILE_CLOSED
because the file handle has already been attached to log_sys.log and
we do not want to close the file twice.

recv_sys_t::read(): Access the first log file via log_sys.log.

This is a port of commit 6e9b421f
adapted to commit 685d958e (MDEV-14425).

The test case is omitted, because it would fail to fail when the log
is stored in persistent memory (or "fake PMEM" on Linux /dev/shm).

The system variable spider_disable_group_by_handler, if on, will
disable the spider group by handler (gbh), and such disablement serves
as workaround to bugs caused by gbh, labelled with spider-gbh on jira,
including MDEV-26247, MDEV-28998, MDEV-29163, MDEV-30392, MDEV-31645.
Tests for these tickets are added accordingly with the workaround in
place.

The problem was that RANGE_OPT_PARAM was not completely initialized in
some cases.
Added bzero() to ensure that all elements are always initialized.

Fixed hang when renaming index to original name

Use Dummy_error_handler in open_stat_tables() to ignore all errors
when opening statistics tables.

In commit 5ea5291d @sanja-byelkin for unknown reason switched the file mode
for 3 Galera tzinfo related test files from 644 -> 755. This exists only
from branch 10.6 onward:

    $ git checkout 10.5
    $ find mysql-test -executable -name *.test -or -executable -name *.result
    (no results)
    $ git checkout 10.6
    $ find mysql-test -executable -name *.test -or -executable -name *.result
    mysql-test/suite/galera/t/mysql_tzmysql-test/suite/galera/t/mysql_tzinfo_to_sql.test
    mysql-test/suite/galera/t/mariadb_tzinfo_to_sql.test
    mysql-test/suite/galera/r/mariadb_tzinfo_to_sql.resultinfo_to_sql.test

mysql-test/suite/galera/t/mariadb_tzinfo_to_sql.test
mysql-test/suite/galera/r/mariadb_tzinfo_to_sql.result

No test file nor test result file should be executable, so run chmod -x
on them.

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.

log_t::create(): Return whether the initialisation succeeded.
It may fail if too large an innodb_log_buffer_size is specified.

check_access() updates ACL of first TABLE_LIST (t1), but not second
(tp). After it is done we copy t1 ACL to tp.

copy_back(): Also copy the dummy empty ib_logfile0 so that
MariaDB Server 10.8 or later can be started after
--copy-back or --move-back.

Thanks to Daniel Black for reporting this.

This is a 10.5 version of
commit ebf36492

Table_cache_instance::operator new[](size_t): Reverted the changes
that were made in commit 8edef482
and move them to the only caller.

Fix spider init bugs (MDEV-22979, MDEV-27233, MDEV-28218) while
preventing regression on old ones (MDEV-30370, MDEV-29904)

Two things are changed:

First, Spider initialisation is made fully synchronous, i.e. it no
longer happens in a background thread. Adapted from the original fix
by nayuta for MDEV-27233. This change itself would cause failure when
spider is initialised early, by plugin-load-add, due to dependency on
Aria and udf function creation, which are fixed in the second and
third parts below. Requires SQL Service, thus porting earlier versions
requires MDEV-27595

Second, if spider is initialised before udf_init(), create udf by
inserting into `mysql.func`, otherwise do it by `CREATE FUNCTION` as
usual. This change may be generalised in MDEV-31401.

Also factor out some clean-up queries from deinit_spider.inc for use
of spider init tests.

A minor caveat is that early spider initialisation will fail if the
server is bootstrapped for the first time, due to missing `mysql`
database which needs to be created by the bootstrap script.

Removing procedures that were created and dropped during init.

This also fixes a race condition where mtr test with
plugin-load-add=ha_spider.so causes post test check to fail as it
expects the procedures to still be there.

There are several plugins in ha_spider: spider, spider_alloc_mem,
spider_wrapper_protocols, spider_rewrite etc.

INSTALL PLUGIN foo SONAME ha_spider causes all the other ones to be
installed by the init queries where foo is any of the plugins.

This introduces unnecessary complexiy. For example it reads
mysql.plugins to find all other plugins, causing the hack of moving
spider plugin init to a separate thread.

To install all spider related plugins, install soname ha_spider should
be used instead.

This also fixes spurious rows in mysql.plugin when installing say only
the spider plugin with `plugin-load-add=SPIDER=ha_spider.so`:

select * from mysql.plugin;
name	dl
spider_alloc_mem	ha_spider.so # should not be here
spider_wrapper_protocols	ha_spider.so # should not be here

Adapted from part of the reverted commit
c160a115.

Use an std::atomic_flag to track thread creation in progress.
This is mainly a cleanup, the effect of this change was not measureable
in my tests.

Add threadpool functionality to restrict concurrency during "batch"
periods (where tasks are added in rapid succession).
This will throttle thread creation more agressively than usual, while
keeping performance at least on-par.

One of these cases is bufferpool load, where async read IOs are executed
without any throttling. There can be as much as 650K read IOs for
loading 10GB buffer pool.

Another one is recovery, where "fake read" IOs are executed.

Why there are more threads than we expect?
Worker threads are not be recognized as idle, until they return to the
standby list, and to return to that list, they need to acquire
mutex currently held in the submit_task(). In those cases, submit_task()
has no worker to wake, and would create threads until default concurrency
level (2*ncpus) is satisfied. Only after that throttling would happen.

use --replace_column for rows, as the numbers are not important.

The problem was that we did not handle errors properly in
JOIN::get_best_combination. In case an early error, JOIN->join_tab would
contain unintialized values, which would cause errors on cleanup().

The error in question was reported earlier, but not noticed until later.
One cause of this is that most of the sql_select.cc code just checks
thd->fatal_error and not thd->is_error().
Fixed by changing of checks of fatal_error to is_error().