On order to unify the two *.yy files easier,
this patch collects all different rules to the end of *.yy files,
so the rule section looks like this:

%%
common rules
different rules

DropIndex, CreateIndex: Remove. The file row0trunc.cc only exists
in MariaDB Server 10.3 so that the crash recovery of TRUNCATE TABLE
operations from older 10.2 and 10.3 servers will work. This dead code
was being used for implementing the MySQL 5.7 WL#6501 TRUNCATE TABLE
that was replaced with a backup-safe implementation in MDEV-13564.

buf_read_ibuf_merge_pages(): Discard any page numbers that are
outside the current bounds of the tablespace, by invoking the
function ibuf_delete_recs() that was introduced in MDEV-20934.
This could avoid an infinite change buffer merge loop on
innodb_fast_shutdown=0, because normally the change buffer merge
would only be attempted if a page was successfully loaded into
the buffer pool.

dict_drop_index_tree(): Add the parameter trx_t*.
To prevent the DROP TABLE crash, do not invoke btr_free_if_exists()
if the entire .ibd file will be dropped. Thus, we will avoid a crash
if the BTR_SEG_LEAF or BTR_SEG_TOP of the index is corrupted,
and we will also avoid unnecessarily accessing the to-be-dropped
tablespace via the buffer pool.

In MariaDB 10.2, we disable the DROP TABLE fix if innodb_safe_truncate=0,
because the backup-unsafe MySQL 5.7 WL#6501 form of TRUNCATE TABLE
requires that the individual pages be freed inside the tablespace.

When commit 09af00cb
removed the crash-upgrade logic of old TRUNCATE TABLE
from MariaDB 10.2 and 10.3, it actually made the return
value of dict_drop_index_tree() redundant.

Adding:
- new class sp_expr_lex
- new grammar rule expr_lex, which includes both reset_lex()
  and its corresponding restore_lex()

Also:
- Moving a few methods from LEX to sp_expr_lex.
- Moving the code from *.yy to new method sp_expr_lex methods
  sp_repeat_loop_finalize() and sp_if_expr().

This change makes it easier to edit the related grammar
(and makes it easier to unify sql_yacc.yy and sql_yacc_ora.yy later).

Simplify task_group destructor.
No tasks must be running or queued into task group is being destroyed.

Add missing static qualifiers.

Fix partitioning and DS-MRR to work together

- In ha_partition::index_end(): take into account that ha_innobase (and
  other engines using DS-MRR) will have inited=RND when initialized for
  DS-MRR scan.
- In ha_partition::multi_range_read_next(): if the MRR scan is using
  HA_MRR_NO_ASSOCIATION mode, it is not guaranteed that the partition's
  handler will store anything into *range_info.
- In DsMrr_impl::choose_mrr_impl(): ha_partition will inquire partitions
  about how much memory their MRR implementation needs by passing
  *buffer_size=0. DS-MRR code didn't know about this (actually it used
  uint for buffer size calculation and would have an under-flow).
  Returning *buffer_size=0 made ha_partition assume that partitions do
  not need MRR memory and pass the same buffer to each of them.

  Now, this is fixed. If DS-MRR gets *buffer_size=0, it will return
  the amount of buffer space needed, but not more than about
  @@mrr_buffer_size.

* Fix ha_{innobase,maria,myisam}::clone. If ha_partition uses MRR on its
  partitions, and partition use DS-MRR, the code will call handler->clone
  with TABLE (*NOT partition*) name as an argument.
  DS-MRR has no way of knowing the partition name, so the solution was
  to have the ::clone() function for the affected storage engine to ignore
  the name argument and get it elsewhere.

After MDEV-11556, not even crash recovery should attempt to access
non-existing pages. But, buf_load() is not validating its input
and must thus be able to ignore missing pages, so that is why
buf_read_page_background() does that.

innodb_shutdown(): Invoke os_aio_free() before btr_search_sys_free().

Remove keywords that are too new.

Almost all threads have gone
- the "ticking" threads, that sleep a while then do some work)
(srv_monitor_thread, srv_error_monitor_thread, srv_master_thread)
were replaced with timers. Some timers are periodic,
e.g the "master" timer.

- The btr_defragment_thread is also replaced by a timer , which
reschedules it self when current defragment "item" needs throttling

- the buf_resize_thread and buf_dump_threads are substitutes with tasks
Ditto with page cleaner workers.

- purge workers threads are not tasks as well, and purge cleaner
coordinator is a combination of a task and timer.

- All AIO is outsourced to tpool, Innodb just calls thread_pool::submit_io()
and provides the callback.

- The srv_slot_t was removed, and innodb_debug_sync used in purge
is currently not working, and needs reimplementation.

The library is capable of
- asynchronous execution of tasks (and optionally waiting for them)
- asynchronous file IO
  This is implemented using libaio on Linux and completion ports on
  Windows. Elsewhere, async io is "simulated", which means worker threads
  are performing synchronous IO.
- timers, scheduling work asynchronously in some point of the future.
  Also periodic timers are implemented.

This is a prerequisite patch required to remove Innodb's
thd_destructor_proxy thread.

The patch implement pre-shutdown functionality for handlers.

A storage engine might need to perform some work after all user
connections are shut down, but before killing off the plugins.

The reason is that an SE could still be using some of the
server infrastructure. In case of Innodb this would be purge threads,
that call into the server to calculate results of virtual function,
acquire MDL locks on tables, or possibly also use the audit plugins.

Create background THDs that are not counted, and do not block
close_connections(), in other words they are just something that plugin
can use internally.

These THD will be used later by Innodb purge threads, and they need THD
to calculate virtual functions.

Since threadpool is using thr_timer, and it also exist in embedded version,
initialize timer also in embedded version

Threadpool will need a functionality for periodic thr_timer
(the threadpool maintainence task is a timer that runs periodically).

Also increase the stack size for the timer thread, 8k won't be enough.

Provide own version of popen/pclose, in attempt to workaround
sporadic erratic behavior of UCRT's one.

using create_w_max_indexes_64.result as a template

- Added dynamic column width fro `user` and `db` columns
- Added option `%` to hide the progress
- Follow up changes from Ubuntu
- Take `INFORMATION_SCHEMA.PROCESSLIST` into account to determine
  progress of the `actual stage`
- Indentation fixes

Closes #215

Apart from page latches (buf_block_t::lock), mini-transactions
are keeping track of at most one dict_index_t::lock and
fil_space_t::latch at a time, and in a rare case, purge_sys.latch.

Let us introduce interfaces for acquiring an index latch
or a tablespace latch.

In a later version, we may want to introduce mtr_t members
for holding a latched dict_index_t* and fil_space_t*,
and replace the remaining use of mtr_t::m_memo
with std::set<buf_block_t*> or with a map<buf_block_t*,byte*>
pointing to log records.

In the test innodb.instant_alter,4k we would be flagging an error
for too large row size. That error was previously only being reported
if the table was being rebuilt. Thus, this merge is fixing a small
omission in MDEV-11369 (instant ADD COLUMN).

revision-id: 673e253724979fd9fe43a4a22bd7e1b2c3a5269e
Author: Kristian Nielsen

Fix missing memory barrier in wait_for_commit.

The function wait_for_commit::wait_for_prior_commit() has a fast path where it
checks without locks if wakeup_subsequent_commits() has already been called.
This check was missing a memory barrier. The waitee thread does two writes to
variables `waitee' and `wakeup_error', and if the waiting thread sees the
first write it _must_ also see the second or incorrect behavior will occur.
This requires memory barriers between both the writes (release semantics) and
the reads (acquire semantics) of those two variables.

Other accesses to these variables are done under lock or where only one thread
will be accessing them, and can be done without barriers (relaxed semantics).

btr_create(), btr_root_raise_and_insert(): Write a MLOG_MEMSET record
to set FIL_PAGE_PREV,FIL_PAGE_NEXT to FIL_NULL, instead of writing
two MLOG_4BYTES records.

For ROW_FORMAT=COMPRESSED pages, we will not use MLOG_MEMSET
because we want the crash-downgrade to earlier 10.4 releases to succeed.

mlog_parse_nbytes(): Relax the too strict assertion. There is no problem
with MLOG_MEMSET records that affect the uncompressed header of
ROW_FORMAT=COMPRESSED index pages.

Fix incorrect change introduced in the fix for MDEV-20109.

The patch tried to compute a more precise estimate for the record_count
value in SJ-Materialization-Scan strategy (in
Sj_materialization_picker::check_qep).  However the new formula is worse
as it produces extremely optimistic results in common cases where
SJ-Materialization-Scan should be used)

The old formula produces pessimistic results in cases when Sj-Materialization-
Scan is unlikely to be a good choice anyway. So, the old behavior is better.

Move row size check to early CREATE/ALTER TABLE phase. Stop checking
on table open.

dict_index_add_to_cache(): remove parameter 'strict', stop checking row size

dict_index_t::record_size_info_t: this is a result of row size check operation

create_table_info_t::row_size_is_acceptable(): performs row size check.
Issues error or warning. Writes first overflow field to InnoDB log.

create_table_info_t::create_table(): add row size check

dict_index_t::record_size_info(): this is a refactored version
of dict_index_t::rec_potentially_too_big(). New version doesn't change global
state of a program but return all interesting info. And it's callers who
decide how to handle row size overflow.

dict_index_t::rec_potentially_too_big(): removed