If a join query uses a derived table (view / CTE) with GROUP BY clause then
the execution plan for such join may employ split optimization. When this
optimization is employed the derived table is not materialized. Rather only
some partitions of the derived table are subject to grouping. Split
optimization can be applied only if:
- there are some indexes over the tables used in the join specifying the
  derived table whose prefixes partially cover the field items used in the
  GROUP BY list (such indexes are called splitting indexes)
- the WHERE condition of the join query contains conjunctive equalities
  between columns of the derived table that comprise major parts of
  splitting indexes and columns of the other join tables.

When the optimizer evaluates extending of a partial join by the rows of the
derived table it always considers a possibility of using split optimization.
Different splitting indexes can be used depending on the extended partial
join. At some rare conditions, for example, when there is a non-splitting
covering index for a table joined in the join specifying the derived table
usage of a splitting index to produce rows needed for grouping may be still
less beneficial than usage of such covering index without any splitting
technique. The function JOIN_TAB::choose_best_splitting() must take this
into account.

Approved by Oleksandr Byelkin <sanja@mariadb.com>

Silence a warning about an uninitialized variable that was
introduced by commit d8fa71a0.

This commit reduces the likelihood of getting a busy port on
quick restarts with rsync SST (problem MDEV-25818) and fixes
a number of other flaws in SST scripts, adds new functionality,
and also synchronizes the xtrabackup-v2 script with the
mariabackup script (the latter applies only to the 10.2 branch):

 1) SST via rsync: rsync and stunnel does not always get the right
    time to complete by correctly handling SIGTERM. These utilities
    are now given more time to complete normally (via normal SIGTERM
    processing) before we move on to using "kill -9";
 2) SST via rsync: attempts to terminate an rsync or stunnel process
    (via "kill" utility) are only made if it did not terminated on
    its own;
 3) SST via rsync: if a combination of stunnel and rsync is used,
    then we need to wait for both utilities to finish or stop, not
    just one of them;
 4) The config file and pid file for stunnel are now deleted after
    successful completion of SST on the donor node;
 5) The configs and pid files from rsync and stunnel should not be
    deleted unless these utilities succeed (or are sucessfully
    terminated) on the joiner node;
 6) The configs and pid files now excluded from transfer via rsync;
 7) Spaces in paths are now valid for config files as well (when
    used with SST via rsync or mariabackup / xtrabackup[-v2]);
 8) SST via mariabackup: added preliminary verification of keys and
    certificates that are used when establishing a connection using
    SSL (to avoid long timeouts and improve diagnostics) - by analogy
    with how it is done for the xtrabackup-v2 (plus check for CA file),
    while that check is skipped if the user does not have openssl
    installed (or does not have diff utility);
 9) Added backup-threads=<n> configuration option which adds
    "--parallel=<n>" for mariabackup / xtrabackup at backup and
    move-back stages;
10) Added encrypt-threads and encrypt-chunk-size configuration
    options for xbcrypt management (when xbcrypt is used);
11) Small optimization: checking the socat version and adding
    a file with parameters for 2048-bit Diffie-Hellman (if necessary)
    is done only if the user has not specified "dhparam=" in the
    "sockopt" option value;
12) SST via rsync now supports "backup-threads" configuration option
    (in server-related sections or in the "[sst]");
13) Determining the number of available processors is now supported
    for FreeBSD + mariabackup/xtrabackup: before that we might have
    problems with "--compact" (rebuild indexes) or qpress on FreeBSD;
14) The check_pid() function should not raise an error state in
    the rare cases when the pid file was created, but it is empty,
    or if it is deleted right during the check, or when zero is read
    from the pid file;
15) Iproved templates that are used to check if a requested socket
    is "listening" when using the ss utility;
16) Shortened some other templates for socket state utilities;
17) Temporary files created by mariabackup / xtrabackup are moved
    to a separate subdirectory inside tmpdir (so they don't get
    mixed with other temporary files, which can make debugging
    more difficult);
18) 10.2 only: the script for SST via xtrabackup-v2 has been brought
    in full compliance with all the bugfixes made for mariabackup (as
    it previously contained many flaws compared to the updated script
    for mariabackup).

MDEV-25576: The statement EXPLAIN running as regular statement and as prepared statement produces different results for UPDATE with subquery

Both EXPLAIN and EXPLAIN EXTENDED statements produce different results set
in case it is run in normal way and in PS mode for the statements
UPDATE/DELETE with subquery.

The use case below reproduces the issue:
MariaDB [test]> CREATE TABLE t1 (c1 INT KEY) ENGINE=MyISAM;
Query OK, 0 rows affected (0,128 sec)

MariaDB [test]> CREATE TABLE t2 (c2 INT) ENGINE=MyISAM;
Query OK, 0 rows affected (0,023 sec)

MariaDB [test]> CREATE TABLE t3 (c3 INT) ENGINE=MyISAM;
Query OK, 0 rows affected (0,021 sec)

MariaDB [test]> EXPLAIN EXTENDED UPDATE t3 SET c3 =
    -> ( SELECT COUNT(d1.c1) FROM ( SELECT a11.c1 FROM t1 AS a11
    -> STRAIGHT_JOIN t2 AS a21 ON a21.c2 = a11.c1 JOIN t1 AS a12
    -> ON a12.c1 = a11.c1 ) d1 );
+------+-------------+-------+------+---------------+------+---------+------+------+----------+--------------------------------+
| id   | select_type | table | type | possible_keys | key  | key_len | ref  | rows | filtered | Extra                          |
+------+-------------+-------+------+---------------+------+---------+------+------+----------+--------------------------------+
|    1 | PRIMARY     | t3    | ALL  | NULL          | NULL | NULL    | NULL |    0 |   100.00 |                                |
|    2 | SUBQUERY    | NULL  | NULL | NULL          | NULL | NULL    | NULL | NULL |     NULL | Impossible WHERE noticed after reading const tables
+------+-------------+-------+------+---------------+------+---------+------+------+----------+--------------------------------+
2 rows in set (0,002 sec)

MariaDB [test]> PREPARE stmt FROM
    -> EXPLAIN EXTENDED UPDATE t3 SET c3 =
    -> ( SELECT COUNT(d1.c1) FROM ( SELECT a11.c1 FROM t1 AS a11
    -> STRAIGHT_JOIN t2 AS a21 ON a21.c2 = a11.c1 JOIN t1 AS a12
    -> ON a12.c1 = a11.c1 ) d1 );
Query OK, 0 rows affected (0,000 sec)
Statement prepared

MariaDB [test]>  EXECUTE stmt;
+------+-------------+-------+------+---------------+------+---------+------+------+----------+--------------------------------+
| id   | select_type | table | type | possible_keys | key  | key_len | ref  | rows | filtered | Extra                          |
+------+-------------+-------+------+---------------+------+---------+------+------+----------+--------------------------------+
|    1 | PRIMARY     | t3    | ALL  | NULL          | NULL | NULL    | NULL |    0 |   100.00 |                                |
|    2 | SUBQUERY    | NULL  | NULL | NULL          | NULL | NULL    | NULL | NULL |     NULL | no matching row in const table |
+------+-------------+-------+------+---------------+------+---------+------+------+----------+--------------------------------+
2 rows in set (0,000 sec)

The reason by that different result sets are produced is that on execution
of the statement 'EXECUTE stmt' the flag SELECT_DESCRIBE not set
in the data member SELECT_LEX::options for instances of SELECT_LEX that
correspond to subqueries used in the UPDTAE/DELETE statements.

Initially, these flags were set on parsing the statement
  PREPARE stmt FROM "EXPLAIN EXTENDED UPDATE t3 SET ..."
but latter they were reset before starting real execution of
the parsed query during handling the statement 'EXECUTE stmt';

So, to fix the issue the functions mysql_update()/mysql_delete()
have been modified to set the flag SELECT_DESCRIBE forcibly
in the data member SELECT_LEX::options for the primary SELECT_LEX
of the UPDATE/DELETE statement.

to print all arguments of _verbose(), not just the number of them

This reverts commit 17106c98.

InnoDB should calculate the MBR for the first field of
spatial index and do the comparison with the clustered
index field MBR. Due to MDEV-25459 refactoring, InnoDB
calculate the length of the first field and fails with
too long column error.

The only call of the virtual member function
handler::update_table_comment() was removed in
commit 82d28fad (MySQL 5.5.53)
but the implementation was not removed.

The only non-trivial implementation was for InnoDB. The information
is now returned via handler::get_foreign_key_create_info() and
ha_statistics::delete_length.

The problem was that when LOCK TABLES where unwinded as part of
a killed connection, unlink_all_closed_tables() did not like that
there was uncommited transactions.
Fixed by doing a rollback of any open transaction in this particular case.

cherry-pick commit: 1fff2398
MDEV-22530 post push fixes from 10.6.

Followup. If the KILL happens - report it as a failure,
don't eat it up silently. Note that this has to be done after `table_name`
is populated, so that the error message could show it.

The following features have been added:

1) Automatic addition of the pf = ip6 option for socat
   when it can be recognized by the format of the connection
   address;
2) Automatically add or remove extra commas at the beginning
   and at the end of sockopt, for example, sockopt='pf=ip6'
   and sockopt=',pf=ip6' work equally well;

Also, due to interference in the code of the get_transfer()
function, I also refactored it and now:

3) encrypt = 4 is supported not only for xtrabackup-v2,
   but also for mariabackup - this can help with migration
   from Percona;
4) Improved setting of 'commonname' option for encrypt=3
   and encrypt=4 modes;

mbstream is already supported as a format name after MDEV-24580,
but additional code refactoring has been done to correctly display
the format name in log files and to check if the mbstream utility
is in the path. Also, for xtrabackup-v2 (only available in the 10.2)
both utilities are supported - both xbstram and mbstream, since they
are interchangeable in this context. In this case, the original
innobackupex always receives the correct --stream=xbstream option
as input, but the user can actually try to use the mbstream utility
during the transfer (if the user explicitly specifies this in the
configuration file).

- Patch addresses the problem to fix double free of
transaction if it is own transaction.

		FTS add index fails

Problem:
========
InnoDB double frees the table if auxiliary fts table
creation fails and fails to set the dict operation
for the transaction. It leads to failure while
dropping newly added index.

Solution:
=========
  InnoDB should avoid double freeing and set the
dictionary operation of transaction in
fts_create_common_tables()

InnoDB truncate table fails to load the fts stopword table into
cache. In that case, InnoDB double frees the truncate creation
transaction. InnoDB should free the transaction which was
created inside ha_innobase::create.

The is_local_ip function that used in Galera SST scripts now
incorrectly identifies ip-addresses falling under the "127.0.0.0/8"
netmask as non-local ip, although they certainly belong to the
loopback interface. This commit fixes this flaw.

don't require tar/gtar, git, getconf, groff/nroff, and ruby.

when cmake is re-run and include(FindJAVA) is skipped,
JAVA_FOUND should still be set. Same for JNI.

report correct error codes in ed25519.
Invalid value stored in the user table or an OpenSSL error is CR_ERROR.
When a user provided incorrect password when logging in -
it's CR_AUTH_USER_CREDENTIALS.

In the code existed just before this patch binding of a table reference to
the specification of the corresponding CTE happens in the function
open_and_process_table(). If the table reference is not the first in the
query the specification is cloned in the same way as the specification of
a view is cloned for any reference of the view. This works fine for
standalone queries, but does not work for stored procedures / functions
for the following reason.
When the first call of a stored procedure/ function SP is processed the
body of SP is parsed. When a query of SP is parsed the info on each
encountered table reference is put into a TABLE_LIST object linked into
a global chain associated with the query. When parsing of the query is
finished the basic info on the table references from this chain except
table references to derived tables and information schema tables is put
in one hash table associated with SP. When parsing of the body of SP is
finished this hash table is used to construct TABLE_LIST objects for all
table references mentioned in SP and link them into the list of such
objects passed to a pre-locking process that calls open_and_process_table()
for each table from the list.
When a TABLE_LIST for a view is encountered the view is opened and its
specification is parsed. For any table reference occurred in
the specification a new TABLE_LIST object is created to be included into
the list for pre-locking. After all objects in the pre-locking have been
looked through the tables mentioned in the list are locked. Note that the
objects referenced CTEs are just skipped here as it is impossible to
resolve these references without any info on the context where they occur.
Now the statements from the body of SP are executed one by one that.
At the very beginning of the execution of a query the tables used in the
query are opened and open_and_process_table() now is called for each table
reference mentioned in the list of TABLE_LIST objects associated with the
query that was built when the query was parsed.
For each table reference first the reference is checked against CTEs
definitions in whose scope it occurred. If such definition is found the
reference is considered resolved and if this is not the first reference
to the found CTE the the specification of the CTE is re-parsed and the
result of the parsing is added to the parsing tree of the query as a
sub-tree. If this sub-tree contains table references to other tables they
are added to the list of TABLE_LIST objects associated with the query in
order the referenced tables to be opened. When the procedure that opens
the tables comes to the TABLE_LIST object created for a non-first
reference to a CTE it discovers that the referenced table instance is not
locked and reports an error.
Thus processing non-first table references to a CTE similar to how
references to view are processed does not work for queries used in stored
procedures / functions. And the main problem is that the current
pre-locking mechanism employed for stored procedures / functions does not
allow to save the context in which a CTE reference occur. It's not trivial
to save the info about the context where a CTE reference occurs while the
resolution of the table reference cannot be done without this context and
consequentially the specification for the table reference cannot be
determined.

This patch solves the above problem by moving resolution of all CTE
references at the parsing stage. More exactly references to CTEs occurred in
a query are resolved right after parsing of the query has finished. After
resolution any CTE reference it is marked as a reference to to derived
table. So it is excluded from the hash table created for pre-locking used
base tables and view when the first call of a stored procedure / function
is processed.
This solution required recursive calls of the parser. The function
THD::sql_parser() has been added specifically for recursive invocations of
the parser.

ha_innobase::open(): If the table is only being opened by purge
for evaluating virtual column values, avoid invoking
initialize_auto_increment(), because the purge thread may already
be holding an shared latch on the clustered index root page.
Shared latches are not recursive. The additional request would lead
to a hang if another thread has started waiting for an exclusive latch.

MDEV-22462: Item_in_subselect::create_single_in_to_exists_cond(JOIN *, Item **, Item **): Assertion `false' failed.

Item_in_subselect::create_single_in_to_exists_cond() should handle the
case where the subquery is a table-less select but it is not a result
of a UNION.

(Table-less subqueries like "(SELECT 1)" are "substituted" with their select
list, but table-less subqueries with WHERE or HAVING clause, like
"(SELECT 1 WHERE ...)" are not substituted. They are handled with regular
execution path)

Another batch of changes that should make the SST process
more reliable in all scenarios:

 1) Added hostname or CN verification when stunnel is used
    with certificate chain verification (verifyChain = yes);
 2) Added check for the absence of the stunnel utility for
    mtr tests;
 3) Deletion of working files before and after SST is done
    more accurately;
 4) rsync on joiner can be run even if the path to its
    configuration file contains spaces;
 5) More accurate directory creation (for data files and
    for logs);
 6) IST with mysqldump no longer turns off statement logging;
 7) Reset password for mysqldump when password is empty but
    username is specified;
 8) More reliable quoting when generating statements in
    wsrep_sst_mysqldump;
 9) Added explicit generation of 2048-bit Diffie-Hellman
    parameters for sockat < 1.7.3, by analogy with xtrabackup;
10) Compression parameters for qpress are read from all
    suitable server groups in configuration file, as well as
    from the [sst] and [xtrabackup] groups;
11) Added a test that checks compression using qpress;
12) Checking for optional utilities is modified to work even
    if they implemented as built-in shell commands (unlikely
    on real systems, but more reliable).

Another batch of changes that should make the SST process
more reliable in all scenarios:

 1) Added hostname or CN verification when stunnel is used
    with certificate chain verification (verifyChain = yes);
 2) Added check for the absence of the stunnel utility for
    mtr tests;
 3) Deletion of working files before and after SST is done
    more accurately;
 4) rsync on joiner can be run even if the path to its
    configuration file contains spaces;
 5) More accurate directory creation (for data files and
    for logs);
 6) IST with mysqldump no longer turns off statement logging;
 7) Reset password for mysqldump when password is empty but
    username is specified;
 8) More reliable quoting when generating statements in
    wsrep_sst_mysqldump;
 9) Added explicit generation of 2048-bit Diffie-Hellman
    parameters for sockat < 1.7.3, by analogy with xtrabackup;
10) Compression parameters for qpress are read from all
    suitable server groups in configuration file, as well as
    from the [sst] and [xtrabackup] groups;
11) Added a test that checks compression using qpress;
12) Checking for optional utilities is modified to work even
    if they implemented as built-in shell commands (unlikely
    on real systems, but more reliable).

m_status == DA_OK_BULK' failed in Diagnostics_area::message from
get_schema_tables_record

Analysis: SET NAMES changes character set for character_set_client,
character_set_connection, character_set_results to 'filename'. The .frm file of view
has @xx sequences in the SELECT query, which give parsing error because 'filename'
character set is not parser friendly. When we get parsing error (ER_PARSE_ERROR), we
directly return true without setting error status. This is caught later in assertion.
Fix: Disallow 'filename' character set in SET NAMES because it is not parser
friendly.

before change test:

 strace -fe trace=file -o /tmp/f.strace sql/mysqld --datadir=/tmp/d --log-bin=foo-bin                      --help --verbose && ls -la /tmp/
...
'mysqladmin variables' instead of 'mysqld --verbose --help'.

total 0
drwxrwxr-x.  2 dan  dan   60 May 19 18:05 .
drwxrwxrwt. 27 root root 640 May 19 18:03 ..
-rw-rw----.  1 dan  dan    0 May 19 18:05 foo-bin.index

In Item_field::fix_fields(): when the item was resolved to an Item_field
in the SELECT's select_list, copy the Item_field's "depended_from" field.

Failure to do so caused the item to have incorrect attributes: it pointed
to a Field in an upper select but used_tables() didn't return
OUTER_REF_TABLE_BIT.

Post push fix to address test issue.