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.

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.

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 MDEV-22769 introduced srv_shutdown_state=SRV_SHUTDOWN_INITIATED in
commit efc70da5
we forgot to adjust a few checks for SRV_SHUTDOWN_NONE.

In the initial shutdown step, we are waiting for the background
DROP TABLE queue to be processed or discarded. At that time,
some background tasks (such as buffer pool resizing or dumping
or encryption key rotation) may be terminated, but others must
remain running normally.

srv_purge_coordinator_suspend(), srv_purge_coordinator_thread(),
srv_start_wait_for_purge_to_start(): Treat SRV_SHUTDOWN_NONE
and SRV_SHUTDOWN_INITIATED equally.

MDEV-19320 Sequence gets corrupted and produces ER_KEY_NOT_FOUND
           (Can't find record) after ALTER .. ORDER BY

MDEV-19977 Assertion `(0xFUL & mode) == LOCK_S ||
           (0xFUL & mode) == LOCK_X' failed in lock_rec_lock

MDEV-22728: SIGFPE in Unique::get_cost_calc_buff_size from prepare_search_best_index_intersect on optimized builds

For low sort_buffer_size, in the cost calculation of using the Unique object the elements in the tree were evaluated to 0, make sure to have atleast 1 element in the Unique tree.

Also for the function Unique::get allocate memory for atleast MERGEBUFF2+1 keys.

This bug is the same as the bug MDEV-17024. The crashes caused by these
bugs were due to premature cleanups of the unit specifying recursive CTEs
that happened in some cases when there were several outer references the
same recursive CTE.
The problem of premature cleanups for recursive CTEs could be already
resolved by the correction in TABLE_LIST::set_as_with_table() introduced
in this patch. ALL other changes introduced by the patches for MDEV-17024
and MDEV-22748 guarantee that this clean-ups are performed as soon as
possible: when the select containing the last outer reference to a
recursive CTE is being cleaned up the specification of the recursive CTE
should be cleaned up as well.

lock_check_trx_id_sanity(): Because the argument of UNIV_LIKELY
or __builtin_expect() can be less than sizeof(trx_id_t) on 32-bit
systems, it cannot reliably perform an implicit comparison to 0.

page_zip_fields_decode(): Do not dereference index=NULL.
Instead, return NULL early. The only caller does not care
about the values of output parameters in that case.

This bug was introduced in MySQL 5.7.6 by
mysql/mysql-server@9eae0edb7a8e4004328e61157f5f3b39cebe1b2b
and in MariaDB 10.2.2 by
commit 2e814d47.

Thanks to my son for pointing this out after investigating
the output of a static analysis tool.

Compiler tells something about argument-dependent lookup. I do not
understand how that ADL works. But I know that such operators should
be free functions, instead of methods:
http://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Ro-symmetric

Such syntax defines 'friend' free functions.

When processing a query with a recursive CTE a temporary table is used for
each recursive reference of the CTE. As any temporary table it uses its own
mem-root for table definition structures. Due to specifics of the current
implementation of ANALYZE stmt command this mem-root can be freed only at
the very of query processing. Such deallocation of mem-root memory happens
in close_thread_tables(). The function looks through the list of the tmp
tables rec_tables attached to the THD of the query and frees corresponding
mem-roots. If the query uses a stored function then such list is created
for each query of the function. When a new rec_list has to be created the
old one has to be saved and then restored at the proper moment.
The bug occurred because only one rec_list for the query containing CTE was
created. As a result close_thread_tables() freed tmp mem-roots used for
rec_tables prematurely destroying some data needed for the output produced
by the ANALYZE command.

The background drop table queue in InnoDB is a work-around for
cases where the SQL layer is requesting DDL on tables on which
transactional locks exist.

One such case are XA transactions. Our test case exploits the
fact that the recovery of XA PREPARE transactions will
only resurrect InnoDB table locks, but not MDL that should
block any concurrent DDL.

srv_shutdown_t: Introduce the srv_shutdown_state=SRV_SHUTDOWN_INITIATED
for the initial part of shutdown, to wait for the background drop
table queue to be emptied.

srv_shutdown_bg_undo_sources(): Assign
srv_shutdown_state=SRV_SHUTDOWN_INITIATED
before waiting for the background drop table queue to be emptied.

row_drop_tables_for_mysql_in_background(): On slow shutdown, if
no active transactions exist (excluding ones that are in
XA PREPARE state), skip any tables on which locks exist.

row_drop_table_for_mysql(): Do not unnecessarily attempt to
drop InnoDB persistent statistics for tables that have
already been added to the background drop table queue.

row_mysql_close(): Relax an assertion, and free all memory
even if innodb_force_recovery=2 would prevent the background
drop table queue from being emptied.