because ALTER TABLE ... DROP SYSTEM VERSIONING
is not just a change in the table structure, it also deletes
all historical rows

also

* don't modify write_set
* backup/restore rpl_write_set

so any other value of ALGORITHM or LOCK disables online alter

use ht->start_consistent_snapshot() instead

no functional changes here

two new tests:
* alter table times out because of a long concurrent trx
* alter table adds a column in the middle

* Log rows in online_alter_binlog.
* Table online data is replicated within dedicated binlog file
* Cached data is written on commit.
* Versioning is fully supported.
* Works both wit and without binlog enabled.

* For now savepoints setup is forbidden while ONLINE ALTER goes on.
  Extra support is required. We can simply log the SAVEPOINT query events
  and replicate them together with row events. But it's not implemented
  for now.

* Cache flipping:

  We want to care for the possible bottleneck in the online alter binlog
  reading/writing in advance.

  IO_CACHE does not provide anything better that sequential access,
  besides, only a single write is mutex-protected, which is not suitable,
  since we should write a transaction atomically.

  To solve this, a special layer on top Event_log is implemented.
  There are two IO_CACHE files underneath: one for reading, and one for
  writing.

  Once the read cache is empty, an exclusive lock is acquired (we can wait
  for a currently active transaction finish writing), and flip() is emitted,
  i.e. the write cache is reopened for read, and the read cache is emptied,
  and reopened for writing.

  This reminds a buffer flip that happens in accelerated graphics
  (DirectX/OpenGL/etc).

  Cache_flip_event_log is considered non-blocking for a single reader and a
  single writer in this sense, with the only lock held by reader during flip.

  An alternative approach by implementing a fair concurrent circular buffer
  is described in MDEV-24676.

* Cache managers:
  We have two cache sinks: statement and transactional.
  It is important that the changes are first cached per-statement and
  per-transaction.
  If a statement fails, then only statement data is rolled back. The
  transaction moves along, however.

  Turns out, there's no guarantee that TABLE well persist in
  thd->open_tables to the transaction commit moment.
  If an error occurs, tables from statement are purged.
  Therefore, we can't store te caches in TABLE. Ideally, it should be
  handlerton, but we cut the corner and store it in THD in a list.

Event_log is supposed to be a basic logging class that can write events in
a single file.

MYSQL_BIN_LOG in comparison will have:
* rotation support
* index files
* purging
* gtid and transactional information handling.
* is dedicated for a general-purpose binlog

* Eliminate most usages of THD::use_trans_table. Only 3 left, and they are
  at quite high levels, and really essential.
* Eliminate is_transactional argument when possible. Lots of places are
  left though, because of some WSREP error handling in
  MYSQL_BIN_LOG::set_write_error.
* Remove junk binlog functions from THD
* binlog_prepare_pending_rows_event is moved to log.cc inside MYSQL_BIN_LOG
  and is not anymore template. Instead it accepls event factory with a type
  code, and a callback to a constructing function in it.

pump up binlog and cache manager to level of binlog_log_row_internal

1. Change m_size to uint. This removes some implicit conversions.
  See unpack_row, for instance:
  uint max_cols= MY_MIN(tabledef->size(), cols->n_bits);
2. Improve table_def memory layout by reordering columns

alter_table_online -> alter_table_locknone
gis-alter_table_online -> gis-alter_table

it was redundant, duplicating vcol_type == VCOL_GENERATED_STORED.

Note that VCOL_DEFAULT is not "stored", "stored vcol" means that after
rnd_next or index_read/etc the field value is already in the record[0]
and does not need to be calculated separately

unpack_row() must calculate all stored and indexed vcols
(in fill_extra_persistent_columns()).

Also Update and Delete row events must mark in read_set
all columns needed for calculating all stored and indexed vcols.

If it's done properly in do_apply_event(), it no longer needs
to be repeated per row.

it was created to handle the case of the concurrent
inplace add index. So it should only work in that case,
otherwise it's doing server's job (marks virtual column dependencies)
and hides server's bugs. And it was redundant.

This reverts commit 158a5824.

In 10.11 the generation of mysql-log-rotate was removed in commit
fd0dcad6

There's no need to ignore files that aren't generated.

Include cppcheck and FlawFinder for SAST scanning.
Ignorelists are present for both, so only new problems will trigger a CI
failure.

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.

Often there are small "nitpicky" changes that need to be done to a PR in order to
get it merged. To speed up the merge process, we will ask contributors
if they are ok with the reviewer making those changes.

Other fixups:
Improve PR template rendering in browser's textarea field. Line wrapping at 80
characters provides a bad user experience within the browser, which
handles word wrapping separately. Thus, prefer long lines in this
markdown file.

Remove the "backwards compatibility section". While the contributor
should ideally care about the impact of their patch on the server's
backwards compatibility, this is an advanced topic that is better
presented in a separate document.

Add variable max_used_connections_time to show the time at which
max_used_connections reached its current value. This is useful for
troubleshooting high connection counts. MySQL 8 has this already.

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.

fil_space_t::~fil_space_t(): Invoke ut_free(name) because
doing so in the callers would trip MSAN_OPTIONS=poison_in_dtor=1

handle_slave_io(), handle_slave_sql(), os_thread_exit():
Remove a redundant pthread_exit(nullptr) call, because it
would cause SIGSEGV.

mysql_print_status(): Add MEM_MAKE_DEFINED() to work around
some missing instrumentation around mallinfo2().

que_graph_free_stat_list(): Invoke que_node_get_next(node) before
que_graph_free_recursive(node). That is the logical and
MSAN_OPTIONS=poison_in_dtor=1 compatible way of freeing memory.

ins_node_t::~ins_node_t(): Invoke mem_heap_free(entry_sys_heap).

que_graph_free_recursive(): Rely on ins_node_t::~ins_node_t().

fts_t::~fts_t(): Invoke mem_heap_free(fts_heap).

fts_free(): Replace with direct calls to fts_t::~fts_t().

The failures in free_root() due to MSAN_OPTIONS=poison_in_dtor=1
will be covered in MDEV-30942.

* it isn't "pfs" function, don't call it Item_func_pfs,
  don't use item_pfsfunc.*
* tests don't depend on performance schema, put in the main suite
* inherit from Item_str_ascii_func
* use connection collation, not utf8mb3_general_ci
* set result length in fix_length_and_dec
* do not set maybe_null
* use my_snprintf() where possible
* don't set m_value.ptr on every invocation
* update sys schema to use the format_pico_time()
* len must be size_t (compilation error on Windows)
* the correct function name for double->double is fabs()
* drop volatile hack

AWK is used in autobake-debs.sh for printing information
about created DEB packages.

This can be rewrite with bash inner commands read and echo.

AWK in used in Debian SysV-init and postinst scripts to determine
is there enough space starting MariaDB database or create new
database to target destination.

These AWK scripts can be rewrited to use pure SH or help
using Coreutils which is mandatory for usage of MariaDB currently.

Reasoning behind this is to get rid of one very less used dependency

…with: Test assertion failed

Problem:
=======
Assertion text: 'Value returned by SSS and PS table for Last_Error_Number
should be same.'
Assertion condition: '"1146" = "0"'
Assertion condition, interpolated: '"1146" = "0"'
Assertion result: '0'

Analysis:
========
In parallel replication when slave is started the worker pool gets
activated and it gets cleared when slave stops. Each time the worker pool
gets activated a backup worker pool also gets created to store worker
specific perforance schema information in case of errors. On error, all
relevant information is copied from rpl_parallel_thread to rli and it gets
cleared from thread.  Then server waits for all workers to complete their
work, during this stage performance schema table specific worker info is
stored into the backup pool and finally the actual pool gets cleared. If
users query the performance schema table to know the status of workers the
information from backup pool will be used. The test simulates
ER_NO_SUCH_TABLE error and verifies the worker information in pfs table.
Test works fine if execution occurs in following order.

Step 1. Error occurred 'worker information is copied to backup pool'.
Step 2. handle_slave_sql invokes 'rpl_parallel_resize_pool_if_no_slaves' to
deactivate worker pool, it marks the pool->count=0
Step 3. PFS table is queried, since actual pool is deactivated backup pool
information is read.

If the Step 3 happens prior to Step2 the pool is yet to be deactivated and
the actual pool is read, which doesn't have any error details as they were
cleared. Hence test ocasionally fails.

Fix:
===
Upon error mark the back pool as being active so that if PFS table is
quried since the backup pool is flagged as valid its information will be
read, in case it is not flagged regular pool will be read.

This work is one of the last pieces created by the late Sujatha Sivakumar.