Don't use LIMIT-based query plans if we don't have an accurate estimate
of join output cardinality (the primary reason for that is lack of
data about condition selectivity).

Extend the join prefix to ensure all tables in the duplicate range either are inside or outside the sort nest

Rewriting GRANT/REVOKE grammar to use more bison stack and use Sql_cmd_ style

1. Removing a few members from LEX:
   - uint grant, grant_to_col, which_columns
   - List<LEX_COLUMN> columns
   - bool all_privileges
2. Adding classes Grand_object_name, Lex_grant_object_name
3. Adding classes Grand_privilege, Lex_grand_privilege
4. Adding struct Lex_column_list_privilege_st, class Lex_column_list_privilege
5. Rewriting the GRANT/REVOKE grammar to use new classes and pass them through
   bison stack (rather than directly access LEX members)
6. Adding classes Sql_cmd_grant* and Sql_cmd_revoke*,
   changing GRANT/REVOKE to use LEX::m_sql_cmd.
7. Adding the "sp_handler" grammar rule and removing some duplicate grammar
   for GRANT/REVOKE for different kinds of SP objects.
8. Adding a new rule comma_separated_ident_list, reusing it in:
   - with_column_list
   - colum_list_privilege

ut_align_down(): Preserve the const qualifier. Use C++ casts.

ha_delete_hash_node(): Correct an assertion expression.

fil_page_get_type(): Perform an assumed-aligned read.

page_align(): Preserve the const qualifier. Assume (some) alignment.

page_get_max_trx_id(): Check the index page type.

page_header_get_field(): Perform an assumed-aligned read.

page_get_autoinc(): Perform an assumed-aligned read.

page_dir_get_nth_slot(): Perform an assumed-aligned read.
Preserve the const qualifier.

recv_sys_t::ALIGNMENT: The recv_sys_t::alloc() alignment

When using LTO, one can see optimization of stack variables that
are passed to check_stack_overrun as argument buf. That prevents
proper stack overrun detection.

Add explicit casts when assigning ulint to m_user_space_id.

mtr_log_t and mtr_t::m_log_mode have the same range 0 to 3.

mtr_t::get_log_mode(): Use equivalent static_assert().

mtr_t::m_n_log_recs: Do not exceed the number of bits in uint16_t.

Use bit-fields for some mtr_t members to improve locality of reference.
Because mtr_t is never shared between threads, there are no considerations
regarding concurrent access.

Since commit 5e62b6a5 (MDEV-16264),
purge_sys_t::stop() no longer waited for all purge activity to stop.

This caused problems on FLUSH TABLES...FOR EXPORT because of
purge running concurrently with the buffer pool flush.
The assertion at the end of buf_flush_dirty_pages() could fail.

The, implemented by Vladislav Vaintroub, aims to eliminate race
conditions when stopping or resuming purge:

waitable_task::disable(): Wait for the task to complete, then replace
the task callback function with noop.

waitable_task::enable(): Restore the original task callback function
after disable().

purge_sys_t::stop(): Invoke purge_coordinator_task.disable().

purge_sys_t::resume(): Invoke purge_coordinator_task.enable().

purge_sys_t::running(): Add const qualifier, and clarify the comment.
The purge coordinator task will remain active as long as any purge
worker task is active.

purge_worker_callback(): Assert purge_sys.running().

srv_purge_wakeup(): Merge with the only caller purge_sys_t::resume().

purge_coordinator_task: Use static linkage.

srv_export_innodb_status(): While gathering
innodb_mem_adaptive_hash, acquire btr_search_latches[i]
in order to prevent a race condition with buffer pool resizing.

Release memory as soon as redo log records are processed.

Because the memory allocation and deallocation of parsed redo log
records must be protected by recv_sys.mutex, it is better to avoid
using a std::atomic field for bookkeeping.

buf_page_t::access_time: Keep track of the recv_sys.pages record
allocations. The most significant 16 bits will count allocated
blocks (which were previously counted by buf_page_t::buf_fix_count
in the debug version), and the least significant 16 bits indicate
the number of allocated bytes in the block (which was previously
managed in buf_block_t::modify_clock), which must be a positive
number, up to innodb_page_size. The byte offset 65536 is represented
as the value 0.

recv_recover_page(): Let the caller erase the log.

recv_validate_tablespace(): Acquire recv_sys_t::mutex.

MDEV-21616: Server crash when using "SET STATEMENT max_statement_time=0 FOR desc xxx" lead to collapse

Main select should be pushed first.

row_log_table_get_pk_old_col(): For replacing a NULL value for a
column of the being-added primary key, look up the correct
default value, even if columns had been instantly reordered or
dropped earlier. This ought to have been broken ever since
commit 0e5a4ac2 (MDEV-15562).

Function `signal_waiters` assigned `m_committed_seqno` variable outside of
mutex lock which caused incorrect behavior of WSREP_SYNC_WAIT_UPTO_GTID.
Fixed by moving assignment inside lock. Added handling of OOM and now
error is reported.
Remove hard-coded seqno value and read seqno directly from current node state.

Also added support for MAP_SYNC. It allows to achieve decent performance
with DAX devices even when libpmem is unavailable.

Fixed Windows version of my_msync(): according to manual FlushViewOfFile()
may return before flush is actually completed. It is advised to issue
FlushFileBuffers() after FlushViewOfFile().

ha_innobase::commit_inplace_alter_table(): After
ALTER_STORED_COLUMN_ORDER, ensure that the virtual column metadata
will be reloaded also when the table is not being rebuilt.