Problem was that SHOW CREATE didn't remove PAGE_CHECKSUM=1

Signed-off-by: hygonsoc <hygonsoc@gmail.com>

For a table column `a`, the above expressions logically
equate to false in all cases.

With this patch the optimizer knows about this and queries
like:

SELECT * FROM t1 WHERE a!=a

no longer need to evaluate a!=a for every row.

The same applies if the expression was `a<a`, or `a>a`

An `EXPLAIN SELECT COOUNT(*) FROM t1 WHERE a<a` will show:

id     select_type     table   type    possible_keys   key     key_len ref     rows    Extra
1      SIMPLE  NULL    NULL    NULL    NULL    NULL    NULL    NULL    Impossible WHERE

Similarly `NOT (a!=a)` is always true.

EXPLAIN SELECT COUNT(*) FROM t1 WHERE not (a!=a);
id     select_type     table   type    possible_keys   key     key_len ref     rows    Extra
1      SIMPLE  NULL    NULL    NULL    NULL    NULL    NULL    NULL    Select tables optimized away

With MAX_INDEXIES=64(default), key_map=Bitmap<64> is just a wrapper around
ulonglong and thus "trivial" (can be bzero-ed, or memcpy-ed, and stays
valid still)

With MAX_INDEXES=128, key_map = Bitmap<128> is not a "trivial" type
anymore. The implementation uses MY_BITMAP, and MY_BITMAP contains pointers
which make Bitmap invalid, when it is memcpy-ed/bzero-ed.

The problem in 10.4 is that there are many new key_map members, inside TABLE
or KEY, and those are often memcopied and bzeroed

The fix makes Bitmap "trivial", by inlining most of MY_BITMAP functionality.
pointers/heap allocations are not used anymore.

Parenthesis around table names and derived tables should be allowed
in FROM clauses and some other context as it was in earlier versions.

Returned test queries that used such parenthesis in 10.3 to their
original form. Adjusted test results accordingly.

The deadlock happened between FTWRL under open HANDLER, LOCK TABLE and
DROP DATABASE

Fixed by reverting the previous fix for handler open in
lock_global_read_lock()

Fixed the original (wrong) test case in flush_read_lock.test to be
repeatable.

Windows does atomic writes, as long as they are aligned and multiple
of sector size. this is documented in MSDN.

Fix innodb.doublewrite test to always use doublewrite buffer,
(even if atomic writes are autodetected)

Fallback to detecting if TRIM is enabled, if we cannot determine
seek penalty.

If handler->inited is RND use cloned handler for long unique duplicate search.

Regression after reverting fair THD members constructors/destructors.
vars_list can be used standalone, in such cases destructor is needed.

Part of MDEV-14984 - regression in connect performance

The accessor dtuple_get_nth_v_field() was defined differently between
debug and release builds in MySQL 5.7.8 in
mysql/mysql-server@c47e1751b742454de553937039bbf2bcbe3c6bc7
and a debug assertion to document or enforce the questionable assumption
tuple->v_fields == &tuple->fields[tuple->n_fields] was missing.

This was apparently no problem until MDEV-11369 introduced instant
ADD COLUMN to MariaDB Server 10.3. With that work present, in one
test case, trx_undo_report_insert_virtual() could in release builds
fetch the wrong value for a virtual column.

We replace many of the dtuple_t accessors with const-preserving
inline functions, and fix missing or misleadingly applied const
qualifiers accordingly.

log_checkpoint(), log_make_checkpoint_at(): Remove the parameter
write_always. It seems that the primary purpose of this parameter
was to ensure in the function recv_reset_logs() that both checkpoint
header pages will be overwritten, when the function is called from
the never-enabled function recv_recovery_from_archive_start().

create_log_files(): Merge recv_reset_logs() to its only caller.

Debug instrumentation: Prefer to flush the redo log, instead of
triggering a redo log checkpoint.

page_header_set_field(): Disable a debug assertion that will
always fail due to MDEV-19344, now that we no longer initiate
a redo log checkpoint before an injected crash.

In recv_reset_logs() there used to be two calls to
log_make_checkpoint_at(). The apparent purpose of this was
to ensure that both InnoDB redo log checkpoint header pages
will be initialized or overwritten.
The second call was removed (without any explanation) in MySQL 5.6.3:
mysql/mysql-server@4ca37968da54ddc6b3b6628f41428ddba1c79bb8

In MySQL 5.6.8 WL#6494, starting with
mysql/mysql-server@00a0ba8ad92569fcf08212b3b8cf046dc8a0ce10
the function recv_reset_logs() was not only invoked during
InnoDB data file initialization, but also during a regular
startup when the redo log is being resized.

mysql/mysql-server@45e91679832219e2593c77185342f11f85232b58
in MySQL 5.7.2 removed the UNIV_LOG_ARCHIVE code, but still
did not remove the parameter write_always.

Disable (hopefully temprorary) this check. Also add tests for some serialized
functions.

Originally introduced by e972125f to avoid harmless wait for
LOCK_global_system_variables in a newly created thread, which creation was
initiated by system variable update.

At the same time it opens dangerous hole, when system variable update
thread already released LOCK_global_system_variables and ack_receiver
thread haven't yet completed new THD construction. In this case THD
constructor goes completely unprotected.

Since ack_receiver.stop() waits for the thread to go down, we have to
temporarily release LOCK_global_system_variables so that it doesn't
deadlock with ack_receiver.run(). Unfortunately it breaks atomicity
of rpl_semi_sync_master_enabled updates and makes them not serialized.

LOCK_rpl_semi_sync_master_enabled was introduced to workaround the above.
TODO: move ack_receiver start/stop into repl_semisync_master
enable_master/disable_master under LOCK_binlog protection?

Part of MDEV-14984 - regression in connect performance

Only take LOCK_plugin for plugin system variables.

Reverted optimisation that was originally done for session tracker: it
makes much less sense now. Specifically only if connections would want to
track plugin session variables changes and these changes would actually
happen frequently. If this ever becomes an issue, there're much better
ways to optimise this workload.

Part of MDEV-14984 - regression in connect performance

Rather than parsing session_track_system_variables when thread starts, do
it when first trackable event occurs.

Benchmarked on a 2socket/20core/40threads Broadwell system using sysbench
connect brencmark @40 threads (with select 1 disabled):
101379.77 -> 143016.68 CPS, whereas 10.2 is currently at 137766.31 CPS.

Part of MDEV-14984 - regression in connect performance

When enabling system variables tracker, make a copy of
global_system_variables.session_track_system_variables
under LOCK_global_system_variables. This protects from concurrent variable
updates and potential freed memory access, as well as from variable
reconstruction (which was previously protected by LOCK_plugin).

We can also use this copy as a session variable pointer, so that we don't
have to allocate memory and reconstruct it every time it is referenced.

For this very reason we don't need buffer_length stuff anymore.

As well as don't we need to take LOCK_plugin early in ::enable().
Unified ::parse_var_list() to acquire LOCK_plugin unconditionally.
For no apparent reason it wasn't previously acquired for global
variable update.

Part of MDEV-14984 - regression in connect performance

One less new/delete per connection.

Removed m_mem_flag since most allocs are thread specific. The only
exception are allocs performed during initialization.

Removed State_tracker and Session_tracker constructors as they don't make
sense anymore.

No reason to access session_sysvars_tracker via get_tracker(), so access
it directly instead.

Part of MDEV-14984 - regression in connect performance

One less new/delete per connection.

Part of MDEV-14984 - regression in connect performance

Saves 2 new/delete per connection.

Part of MDEV-14984 - regression in connect performance

tool_list is a temporary list needed only for SET SESSION
session_track_system_variables, so allocate it on stack instead.

Sane reinit() calls.

Saves 2 new/delete per connection.

Part of MDEV-14984 - regression in connect performance

One less new/delete per connection.

Part of MDEV-14984 - regression in connect performance

- Session_sysvars_tracker::server_init_check() -> sysvartrack_validate_value()
- Session_sysvars_tracker::check_var_list()    -> sysvartrack_validate_value()

- Session_sysvars_tracker::server_init_process() -> sysvartrack_global_update()
- sysvartrack_reprint_value()                    -> sysvartrack_global_update()

- sysvartrack_value_len()       -> sysvartrack_session_value_ptr()
- sysvartrack_value_construct() -> sysvartrack_session_value_ptr()

- sysvartrack_update() -> Session_sysvars_tracker::update()
- Session_tracker::server_boot_verify() -> session_tracker_init()
- sysvar_tracker() -> /dev/null

Part of MDEV-14984 - regression in connect performance

- m_enabled is initialised by the base class constructor
- removed unused schema_track_inited
- moved Transaction_state_tracker constructor to declaration
- common enable()
- removed unused Session_sysvars_tracker::check_str()
- classes are "private" by default
- don't even try to compile for embedded

Part of MDEV-14984 - regression in connect performance

- return proper type
- removed useless node argument
- removed useless mem_flag
- classes are "private" by default
- simplified iterators

Part of MDEV-14984 - regression in connect performance

Note: preserved original behaviour, where remaining trackers are not reset
on error from store(). This effectively means subsequent statements will
start tracking from unclean state.

Part of MDEV-14984 - regression in connect performance

Streaming replication must be allowed only in a cluster, where all nodes
have  Galera 4 capability

No need to set SELECT_LEX:explicit_limit when we have a limit clause
that sets only the EXAMINED ROWS

Adjusted the Item_func_group_concat::print function to take into account
limit if present with GROUP_CONCAT

on tablespace files

Fix is to always add Full Control for NetworkService account, for every
file that copyback/moveback copies around.

local_global_read_lock did release all HANDLER's before taking its
MDL_BACKUP_FTWRL# locks. This had a potential race condition if
there was a waiting LOCK TABLE for one of the freed handlers.

Fixed by moving the release of HANDLER's to after the backup locks are
taken.

After commit 8cf7e345 it's not anymore critical to free HANDLER's in
FTWRL, but we will keep the mysql_ha_cleanup_no_free() call until 10.5
to not cause any issues with 10.4 just before it's going GA.