In commit 0f90728b (MDEV-16809)
we introduced the configuration option innodb_log_optimize_ddl
for controlling whether native index creation or table-rebuild
in InnoDB should avoid writing full redo log.

Fungo Wang reported that this option is causing occasional failures.
The reason is that pages may be written to data files in an
inconsistent state. Applying log records to such inconsistent pages
may fail.

The solution is to always invoke PageBulk::finish() before page latches
may be released, to ensure that the page contents is in a consistent
state.

Something similar was implemented in MySQL 8.0.13:
mysql/mysql-server@d1254b947354e0f5b7223b09c521bd85f22e1e31

buf_block_t::skip_flush_check: Remove. Suppressing consistency checks
is a bad idea.

PageBulk::needs_finish(): New predicate: Determine whether
PageBulk::finish() must fix up the page.

PageBulk::init(): Clear PAGE_DIRECTION to ensure that needs_finish()
will hold. We change the field from PAGE_NO_DIRECTION to 0
and back without writing redo log. This trick avoids the need
to introduce any new data member to PageBulk.

PageBulk::insert(): Replace some high-level accessors to bypass
debug assertions related to PAGE_HEAP_TOP that we will be violating
until finish() has been executed.

PageBulk::finish(): Tolerate m_rec_no==0. We must invoke this also
on an empty page, to ensure that PAGE_HEAP_TOP is initialized.

PageBulk::commit(): Always invoke finish().

PageBulk::release(), BtrBulk::pageSplit(), BtrBulk::storeExt(),
BtrBulk::finish(): Invoke PageBulk::finish().

page_simple_validate_old(), page_simple_validate_new():
Require PAGE_N_DIR_SLOTS to be at least 2.

MDEV-22721 (commit eba2d10a)
inadvertently introduced an infinite loop.

page_validate(): Remove the infinite loop.

Linux glibc has deprecated ftime resutlting in a compile error on Fedora-32.

Per manual clock_gettime is the suggested replacement. Because my_timer_milliseconds
is a relative time used by largely the perfomrance schema, CLOCK_MONOTONIC_COARSE
is used. This has been available since Linux-2.6.32.

The low overhead is shows in the unittest:

    $ unittest/mysys/my_rdtsc-t
    1..11
    # ----- Routine ---------------
    # myt.cycles.routine          :             5
    # myt.nanoseconds.routine     :            11
    # myt.microseconds.routine    :            13
    # myt.milliseconds.routine    :            18
    # myt.ticks.routine           :            17
    # ----- Frequency -------------
    # myt.cycles.frequency        :    3596597014
    # myt.nanoseconds.frequency   :    1000000000
    # myt.microseconds.frequency  :       1000000
    # myt.milliseconds.frequency  :          1039
    # myt.ticks.frequency         :           103
    # ----- Resolution ------------
    # myt.cycles.resolution       :             1
    # myt.nanoseconds.resolution  :             1
    # myt.microseconds.resolution :             1
    # myt.milliseconds.resolution :             1
    # myt.ticks.resolution        :             1
    # ----- Overhead --------------
    # myt.cycles.overhead         :           118
    # myt.nanoseconds.overhead    :           234
    # myt.microseconds.overhead   :           222
    # myt.milliseconds.overhead   :            30
    # myt.ticks.overhead          :          4946
    ok 1 - my_timer_init() did not crash
    ok 2 - The cycle timer is strictly increasing
    ok 3 - The cycle timer is implemented
    ok 4 - The nanosecond timer is increasing
    ok 5 - The nanosecond timer is implemented
    ok 6 - The microsecond timer is increasing
    ok 7 - The microsecond timer is implemented
    ok 8 - The millisecond timer is increasing
    ok 9 - The millisecond timer is implemented
    ok 10 - The tick timer is increasing
    ok 11 - The tick timer is implemented

In fsp_path_to_space_name(), we would access a byte right before
the start of the string, tripping AddressSanitizer.

This reverts commit d87006a1
and commit a7634281.

Avoid character set conversion for numeric data in this scenario:

SET NAMES utf8;
CREATE OR REPLACE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1);
SELECT a FROM t1;

- Renaming this virtual method store() to store_str():
    store(const char *str, size_t length, CHARSET_INFO *src_cs, CHARSET_INFO *dst_cs)
  We'll be adding more variants of store*() soon. This change will help to avoid
  ambiguities during overloading.

- Adding a helper method store_ident().

- Renaming store_str(const LEX_CSTRING &s...) to store_lex_cstring(),
  to avoid ambiguties during overloading.

- Adding a helper method store() for backward compatibility, to avoid a lot of
  changes in the code now. But eventually we should replace store() to
  non-ambiguius methods store_str() or store_ident().

- Adding a helper method Protocol::needs_conversion() and reusing it
  in two places.

This version is not optimized yet. It could have bugs because I didn't
check it with unit tests. Also, std::char_traits are not really supported.
So, now it's not possible to create f.ex. a case insensitive string_view.

fil_path_to_space_name(): renamed, moved to another file
and refactored to use string_view

We must prevent InnoDB purge from acquiring MDL on the tables.
Since MDEV-12288, INSERT is generating work for purge.

The only InnoDB change between MySQL 5.7.30 and MySQL 5.7.31
that is applicable to MariaDB Server was applied in
commit 8d061996 (MDEV-23161).

The only InnoDB changes between Percona XtraDB Server 5.6.47-87.0
and 5.6.48-88.0 are related to InnoDB changes between MySQL 5.6.47
and MySQL 5.6.48, which we had already applied.

There were no InnoDB changes between MySQL 5.6.48 and MySQL 5.6.49.

This issue was originally reported by Fungo Wang, along with a fix, as
MySQL Bug #98990.

His suggested fix was applied as part of
mysql/mysql-server@a003fc373d1adb3ccea353b5d7d83f6c4c552383
and released in MySQL 5.7.31.

i_s_metrics_fill(): Add the missing call to Field::set_notnull(),
and simplify some code.

- i_s_fts_index_cache_fill() should take shared lock of fts cache
before accessing index cache to avoid reading stale data.

- Problem is that test case creates iblogfile* files. So existing
ibdata pages could point to future LSN. Fix is that taking the
backup of data before iblogfile* creation and apply it before
exiting the test case.

MDEV-22890 DEADLOCK of threads detected: row0sel.cc S-LOCK / btr0cur.cc S-LOCK / row0quiesce.cc X-LOCK

Problem:
=======
- Read operations are always allowed to hold a secondary index leaf
latch and then look up the corresponding clustered index record.
Flush table operation acquires secondary index latch while holding
a clustered index latch. It leads to deadlock violation.

Fix:
====
- Flush table operation should acquire secondary index before taking
clustered index to avoid deadlock violation with select operation.

Only install wsrep scripts and links if WSREP_ON is actually set

MDEV-22463: Element_type &Bounds_checked_array<Item *>::operator[](size_t) [Element_type = Item *]: Assertion `n < m_size' failed.

Allocate space for fields inside the window function (arguments, PARTITION BY and ORDER BY clause)
in the ref pointer array. All fields inside the window function are part of the temporary
table that is required for the window function computation.

buf_pool_t::page_hash_table::create(): Use aligned_malloc()
for the hash array, to get the page_hash_latch aligned on the
same L1 data cache line as the data that it is protecting.

This form of corruption was only reproduced on MariaDB 10.5.4
after the MDEV-22867 fix was applied in
commit 43120009.

While we do not know how to reproduce this corruption in
MariaDB 10.4, we are applying the code fix without a test case.

btr_cur_pessimistic_update(): Invoke btr_set_instant() if needed.

MDEV-22058: Assertion `!is_set() || (m_status == DA_OK_BULK && is_bulk_op())' failed in Diagnostics_area::set_ok_status

Error state is not stored in check_and_do_in_subquery_rewrites() when there is
illegal combination of optimizer switches. So all the functions eventually
return false. Thus the assetion failure.