- select_describe() should not attempt to produce query plans
  for subqueries if the query is handled by a Select Handler.

- JOIN::save_explain_data_intern should not add links to Explain_select
  for children selects if:
  1. The whole query is handled by the Select Handler, or
  2. this select (and so its children) is handled by Derived Handler.

The idea was borrowed from http://wg21.link/p0052

scope_exit class is a helper, its name is hidden from user in
the namespace detail.

Alternative implementation of scope_exit with std::function
looks slower on goldbolt.org as it may require allocation, etc.
scope_exit doesn't need to own a callable, so beeing a pointer
is enough. And std::decay produces such a pointer from callable.

MDEV-22665: Print ranges in the optimizer trace created for non-indexed columns when optimizer_use_condition_selectivity >2

Now the optimizer trace shows the ranges constructed while getting estimates from EITS

from configuration files

Post-push fix: add mysqd options in backup string in mariabackup sst
script for the case of logging not in syslog.

The test mariabackup.mdev-14447 started failing due to the option
--apply-log-only that became invalid since
commit 9bdf35e9
and had been removed in
commit 8c71c6aa.

- There is a possiblity that metadata record is the only record in
the leftmost leaf page. So change the assertion to check only
previous page.

Make sure to initialize SSL early enough, when encryption plugins is loaded

            increased scalability through even distribution

Rollback segments are allocated to transactions in round-robin fashion.
This is controlled by incrementing a static-scope counter named rseg_slot.

Said logic is not protected by any mutex or use of atomic for the counter.
This potentially can cause the same rollback segment to get allocated to
N different transactions (requesting allocation at the same time).
While this is not an issue as a rollback segment can host multiple
transactions from contention (performance) perspective it is better to
allocate these rollback segments in round-robin fashion.

Fix for the said issue ports use of atomic for the said counter that would
ensure the original design semantic (even distribution through round-robin)
is retained.

MDEV-22370 safe_mutex: Trying to lock uninitialized mutex at /data/src/10.4-bug/sql/rpl_parallel.cc, line 470 upon shutdown during FTWRL

Problem:- When we issue FTWRL with shutdown in parallel, there is race between
FTWRL and shutdown. Shutdown might destroy the mutex (pool->LOCK_rpl_thread_pool)
before FTWRL can lock it. So we can get crash on FTWRL thread

Solution:- mysql_mutex_destroy(pool->LOCK_rpl_thread_pool) should wait for
FTWRL thread to complete its work , and then destroy.
So slave_prepare_for_shutdown will just deactivate the pool, and mutex is destroyed
later in end_slave()

The galera.galera_parallel_autoinc_manytrx mtr test opens and runs test
scenario through 3 connections to node 1 and one connection to node 2.
In the test initialization phase, the test creates two tables 't1' and 'ten'
and then creates a stored procedure 'p1' to operate on these tables.
These 3 create DDL statements are issued through same connection to node 1.

In the next test phase, the mtr script uses send command to launch the call
for the p1 stored procedure through all 3 connections to node 1 and through
one connection to node 2. As the mtr send command is asynchronous,
this test phase is non blocking and fast operation.
Now, if the replication between nodes is slow, it may happen that the
initialization phase DDL statements have not been received or have not been
fully applied in node 2. Therefore there is no guarantee that the test tables
and the stored procedure have been created in node 2. Yet, the test is trying
to call p1 in node 2.

In the failure case error logs, there is error message
"MTR failed: query 'reap' failed: 1305: PROCEDURE test.p1 does not exist"

The reap command through connection to node 2, is the first place where test
execution may observe that test tables and/or stored procedure are not yet
created in node 2.

The fix in this commit adds a wait condition in connection to node 2, to wait
until the stored procedure is created before calling the stored procedure.
The wait is implemented by looking in information_schema.routines for the p1
stored procedure.

galera_ipv6_mariabackup MTR tests

MDEV-21298: mariabackup doesn't read from the [mariadbd] and [mariadbd-X.Y]
server option groups from configuration files
MDEV-21301: mariabackup doesn't read [mariadb-backup] option group in
configuration file

All three issues require to change the same code, that is why their
fixes are joined in one commit.

The fix is in invoking load_defaults_or_exit() and handle_options() for
backup-specific groups separately from client-server groups to let the last
handle_options() call fail on unknown backup-specific options.

The order of options procesing is the following:
1) Load server groups and process server options, ignore unknown
options
2) Load client groups and process client options, ignore unknown
options
3) Load backup groups and process client-server options, exit on
unknown option
4) Process --mysqld-args command line options, ignore unknown options

New global flag my_handle_options_init_variables was added to have
ability to invoke handle_options() for the same allowed options set
several times without re-initialising previously set option values.

--password value destroying is moved from option processing callback to
mariabackup's handle_options() function to have ability to invoke server's
handle_options() several times for the same possible allowed options
set.

Galera invokes wsrep_sst_mariabackup.sh with mysqld command line
options to configure mariabackup as close to the server as possible.
It is not known what server options are supported by mariabackup when the
script is invoked. That is why new mariabackup option "--mysqld-args" is added,
all unknown options that follow this option will be silently ignored.

wsrep_sst_mariabackup.sh was also changed to:
- use "--mysqld-args" mariabackup option to pass mysqld options,
- remove deprecated innobackupex mode,
- remove unsupported mariabackup options:
    --encrypt
    --encrypt-key
    --rebuild-indexes
    --rebuild-threads

The test case that was added for MDEV-21217
(commit b68f1d84)
should have only two possible outcomes for the locking SELECT statement:

(1) The statement is blocked, and the test will eventually fail
with a lock wait timeout. This is what I observed when the
code fix for MDEV-21217 was missing.

(2) The lock conflict will ensure that the statement will execute
after the rollback has completed, and an empty table will be observed.
This is the expected outcome with the recovery fix.

What occasionally happens (in some of our CI environments only, so far)
is that the locking SELECT will return all 1,000 rows of the table that
had been inserted by the transaction that was never supposed to be
committed. One possibility is that the transaction was unexpectedly
committed when the server was killed.

Let us disable the test until the reason of the failure has been
determined and addressed.

With RETURNING it can happen that the user has some privileges on
the table (namely, DELETE), but later needs different privileges
on individual columns (namely, SELECT).

Do the same as in check_grant_column() - ER_COLUMNACCESS_DENIED_ERROR,
not an assert.

trx_roll_must_shutdown(): Correct the condition that detects
the start of shutdown.

Item_func_div::fix_length_and_dec_temporal() set the return data type to
integer in case of @div_precision_increment==0 for temporal input with FSP=0.
This caused Item_func_div to call int_op(), which is not implemented,
so a crash on DBUG_ASSERT(0) happened.

Fixing fix_length_and_dec_temporal() to set the result type to DECIMAL.

MDEV-22499 Assertion `(uint) (table_check_constraints - share->check_constraints) == (uint) (share->table_check_constraints - share->field_check_constraints)' failed in TABLE_SHARE::init_from_binary_frm_image

The patch for MDEV-22111 fixed MDEV-22499 as well.
Adding tests only.

Item_cache_datetime::decimals was always copied from example->decimals
without limiting to 6 (maximum possible fractional digits), so
val_str() later crashed on asserts inside my_time_to_str() and
my_datetime_to_str().

MDEV-22755 CREATE USER leads to indirect SIGABRT in __stack_chk_fail () from fill_schema_user_privileges + *** stack smashing detected *** (on optimized builds)

The code erroneously used buff[100] in a fiew places to make
a GRANTEE value in the form:
  'user'@'host'

Fix:
- Fixing the code to use (USER_HOST_BUFF_SIZE + 6) instead of 100.
- Adding a DBUG_ASSERT to make sure the buffer is enough
- Wrapping the code into a class Grantee_str, to reuse it easier in 4 places.

On large hard disks (> 2TB), the plugin won't function correctly, always
showing 2 TB of available space due to integer overflow. Upgrade table
fields to bigint to resolve this problem.

The last traces of the special InnoDB table names were removed in
commit 0af52734
but we forgot to remove the test case.

Item_default_value did not override val_native(), so the inherited
Item_field::val_native() was called. As a result Item_default_value::calculate()
was not called and Item_field::val_native() was called on a Field
with a non-initialized ptr.

Implementing Item_default_value::val_native() properly.

The real problem was that attempt to roll back cahnes after end of memory in QC was made incorrectly and lead to using uninitialized memory.
(bug has nothing to do with resize operation, it is just lack of resources erro processed incorrectly)

This reverts commit 44339123.

Replacing the slow loop in my_hash_sort_utf8mbX() to the fast
skip_trailing_spaces(), which consumes 8 bytes in one iteration,
and is around 8 times faster on long data.

Also, renaming:
- my_hash_sort_utf8() to my_hash_sort_utf8mb3()
- my_hash_sort_utf8_nopad() to my_hash_sort_utf8mb3_nopad()
to merge to 10.5 easier (automatically?).

 Backported from MYSQL
 Bug #25331425: DISTINCT CLAUSE DOES NOT WORK IN GROUP_CONCAT
    Issue:
    ------
    The problem occurs when:
    1) GROUP_CONCAT (DISTINCT ....) is used in the query.
    2) Data size greater than value of system variable:
    tmp_table_size.

    The result would contain values that are non-unique.

    Root cause:
    -----------
    An in-memory structure is used to filter out non-unique
    values. When the data size exceeds tmp_table_size, the
    overflow is written to disk as a separate file. The
    expectation here is that when all such files are merged,
    the full set of unique values can be obtained.

    But the Item_func_group_concat::add function is in a bit of
    hurry. Even as it is adding values to the tree, it wants to
    decide if a value is unique and write it to the result
    buffer. This works fine if the configured maximum size is
    greater than the size of the data. But since tmp_table_size
    is set to a low value, the size of the tree is smaller and
    hence requires the creation of multiple copies on disk.

    Item_func_group_concat currently has no mechanism to merge
    all the copies on disk and then generate the result. This
    results in duplicate values.

    Solution:
    ---------
    In case of the DISTINCT clause, don't write to the result
    buffer immediately. Do the merge and only then put the
    unique values in the result buffer. This has be done in
    Item_func_group_concat::val_str.

    Note regarding result file changes:
    -----------------------------------
    Earlier when a unique value was seen in
    Item_func_group_concat::add, it was dumped to the output.
    So result is in the order stored in SE. But with this fix,
    we wait until all the data is read and the final set of
    unique values are written to output buffer. So the data
    appears in the sorted order.

    This only fixes the cases when we have DISTINCT without ORDER BY clause
    in GROUP_CONCAT.

innodb: dict_mem_table_add_col - compile warning fix argument 1 null where non-null expected (#1584)

cd /build-mariadb-server-10.5-mysql_release/storage/innobase && /usr/bin/powerpc64le-linux-gnu-g++  -DBTR_CUR_ADAPT -DBTR_CUR_HASH_ADAPT -DCOMPILER_HINTS -DDBUG_TRACE -DEMBEDDED_LIBRARY -DHAVE_BZIP2=1 -DHAVE_C99_INITIALIZERS -DHAVE_CONFIG_H -DHAVE_FALLOC_PUNCH_HOLE_AND_KEEP_SIZE=1 -DHAVE_IB_LINUX_FUTEX=1 -DHAVE_LZ4=1 -DHAVE_LZ4_COMPRESS_DEFAULT=1 -DHAVE_LZMA=1 -DHAVE_NANOSLEEP=1 -DHAVE_OPENSSL -DHAVE_SCHED_GETCPU=1 -DLINUX_NATIVE_AIO=1 -DMUTEX_EVENT -DWITH_INNODB_DISALLOW_WRITES -D_FILE_OFFSET_BITS=64 -Iwsrep-lib/include -Iwsrep-lib/wsrep-API/v26 -I/home/dan/build-mariadb-server-10.5-mysql_release/include -Istorage/innobase/include -Istorage/innobase/handler -Ilibbinlogevents/include -Itpool -Iinclude -Isql  -pie -fPIC -Wl,-z,relro,-z,now -fstack-protector --param=ssp-buffer-size=4 -Wconversion -Wno-sign-conversion -O3 -g -static-libgcc -fno-omit-frame-pointer -fno-strict-aliasing -Wno-uninitialized -D_FORTIFY_SOURCE=2 -DDBUG_OFF -Wall -Wextra -Wformat-security -Wno-format-truncation -Wno-init-self -Wno-nonnull-compare -Wno-unused-parameter -Woverloaded-virtual -Wnon-virtual-dtor -Wvla -Wwrite-strings   -DUNIV_LINUX -D_GNU_SOURCE=1 -fPIC -fvisibility=hidden -std=gnu++11 -o CMakeFiles/innobase_embedded.dir/dict/dict0load.cc.o -c storage/innobase/dict/dict0load.cc
storage/innobase/dict/dict0load.cc: In function ‘const char* dict_process_sys_columns_rec(mem_heap_t*, const rec_t*, dict_col_t*, table_id_t*, const char**, ulint*)’:
storage/innobase/dict/dict0load.cc:1653:26: warning: argument 1 null where non-null expected [-Wnonnull]
    dict_mem_table_add_col(table, heap, name, mtype,
    ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
             prtype, col_len);
             ~~~~~~~~~~~~~~~~
In file included from storage/innobase/include/dict0dict.h:32:0,
                 from storage/innobase/include/btr0pcur.h:30,
                 from storage/innobase/dict/dict0load.cc:31:
storage/innobase/include/dict0mem.h:323:1: note: in a call to function ‘void dict_mem_table_add_col(dict_table_t*, mem_heap_t*, const char*, ulint, ulint, ulint)’ declared here
 dict_mem_table_add_col(
 ^~~~~~~~~~~~~~~~~~~~~~

In case of SELECT without tables which returns either 0 or 1 rows,
JOIN::exec_inner() did not check if the flag representing SQL_CALC_FOUND_ROWS
is set or not and send_records was direclty assigned 0. So SELECT FOUND_ROWS()
was giving 0 in the output. Now it checks if the flag is set, if it is set
send_record=1 else 0. 1 is the number of rows that could have been sent
to the client if the SELECT query had SQL_CALC_FOUND_ROWS.
It is 0 when no rows were sent because the SELECT query did not have
SQL_CALC_FOUND_ROWS.

MDEV-22717: Conditional jump or move depends on uninitialised value(s) in find_uniq_filename(char*, unsigned long)

Fix:
===
Initialize 'number' variable to '0'.

When processing a condition like:
   WHERE timestamp_column='2010-00-01 00:00:00'
don't replace the constant to Item_datetime_literal if the constant
it has zeros (in the month or in the day).