In debug builds, this setting is allowed to be turned off temporarily after it was
turned on during startup. Howewer memory garbage also caused it to be accidentally
turned on when it was disabled at startup.

group concat tree is allocated in a memroot, so the only way to free
memory is to copy a part of the tree into a new memroot.

track the accumilated length of the result, and when it crosses
the threshold  - copy the result into a new tree, free the old one.

do it only for items that inherit from Item_result_field*

move per-object TREE::null_element to be one global
static null_element.

Closes #1262

add a new option --pam-windbind-workaround for a pam plugin to
work around pam_winbind unconditional username lowercasing

only use SHOW TRIGGERS on old (< 5.1.21) servers, otherwise
always use SHOW CREATE TRIGGER and don't fallback.

create mysql and test databases with SQL, not mkdir.

Take into account ps-protocol states.
Note, repace_regex was redundant, because Host column was replaced anyway

Apply dbart's patch to set epoch for all ubuntu releases starting
from bionic. Not only for bionic.

This works for Debian too (VERNUM=unstable, etc).

InnoDB could return the same list again and again if the buffer
passed to trx_recover_for_mysql() is smaller than the number of
transactions that InnoDB recovered in XA PREPARE state.

We introduce the transaction state TRX_PREPARED_RECOVERED, which
is like TRX_PREPARED, but will be set during trx_recover_for_mysql()
so that each transaction will only be returned once.

Because init_server_components() is invoking ha_recover() twice,
we must reset the state of the transactions back to TRX_PREPARED
after returning the complete list, so that repeated traversals
will see the complete list again, instead of seeing an empty list.
Without this tweak, the test main.tc_heuristic_recover would hang
in MariaDB 10.1.

Problem:
========
The mysqlbinlog tool is leaking memory, causing failures in various tests when
compiling and testing with AddressSanitizer or LeakSanitizer like this:

cmake -DCMAKE_BUILD_TYPE=Debug -DWITH_ASAN:BOOL=ON /path/to/source
make -j$(nproc)
cd mysql-test
ASAN_OPTIONS=abort_on_error=1 ./mtr --parallel=auto rpl.rpl_row_mysqlbinlog

CURRENT_TEST: rpl.rpl_row_mysqlbinlog

Direct leak of 112 byte(s) in 1 object(s) allocated from:
#0 0x4eff87 in __interceptor_malloc (/dev/shm/5.5/client/mysqlbinlog+0x4eff87)
#1 0x60eaab in my_malloc /mariadb/5.5/mysys/my_malloc.c:41:10
#2 0x5300dd in Log_event::read_log_event(char const*, unsigned int, char const**,
   Format_description_log_event const*, char) /mariadb/5.5/sql/log_event.cc:1568:
#3 0x564a9c in dump_remote_log_entries(st_print_event_info*, char const*)
/mariadb/5.5/client/mysqlbinlog.cc:1978:17

Analysis:
========
'mysqlbinlog' tool is being used to read binary log events from a remote server.
While reading binary log, if a fake rotate event is found following actions are
taken.

If 'to-last-log' option is specified, then fake rotate event is processed.
In the absence of 'to-last-log' skip the fake rotate event.

In this skipped case the fake rotate event object is not getting cleaned up
resulting in memory leak.

Fix:
===
Cleanup the fake rotate event.

This issues is already fixed in MariaDB 10.0.23 and higher versions as part of
commit c3018b0f

dict_create_foreign_constraints_low(): Tolerate the keywords
IGNORE and ONLINE between the keywords ALTER and TABLE.

We should really remove the hacky FOREIGN KEY constraint parser
from InnoDB.

MDEV-9465 The constructor StringBuffer(const char *str, size_t length, const CHARSET_INFO *cs) looks suspicious

Removing the suspicious constructor, it's not used in the code anyway.

The command SHOW INDEXES ignored setting of the system variable
use_stat_tables to the value of 'preferably' and and showed statistical
data received from the engine. Similarly queries over the table
STATISTICS from INFORMATION_SCHEMA ignored this setting. It happened
because the function fill_schema_table_by_open() did not read any data
from statistical tables.

In the case of error when object shapes are half-collected we need
to set the NULL at the vertice's list.

MDEV-17297: stats.records=0 for a table of Archive engine when it has rows, when we run ANALYZE command

Archive storage engine assumed that any query that attempts to read from
the table will call ha_archive::info() beforehand. ha_archive would flush
un-written data in that call (this would make it visible for the reads).

Break this assumption. Flush the data when the table is opened for reading.

This way, one can do multiple write statements without causing a flush, but
as soon as we might need the data, we flush it.

For single table updates and multi-table updates , engine independent statistics were not being
read even if the statistics were collected.
Fixed it, so when the optimizer_use_condition_selectivity > 2 then we would read the available
statistics for update queries.

before:
(gdb) p sizeof(PFS_events_waits)
$1 = 184

after:
(gdb) p sizeof(PFS_events_waits)
$1 = 160

no functional changes

Always set SERVER_MORE_RESULTS_EXIST when executing stored procedure statements

If statements produce a result, EOF packet needs this flag (SP ends
with an OK packet). IF statetement does not produce a result, affected rows
count are part of the final OK packet.

within stored procedure

Always set SERVER_MORE_RESULTS_EXIST when executing stored procedure.
statements

If statements produce a result, EOF packet needs this flag (SP ends with
an OK packet). IF statetement does not produce a result, affected rows
count are part of the final OK packet.

Fixed by adding more rows to a table

Other things:
- Speed up index_merge tests 20% by adding begin/commit around loops that
  generated rows.

For some reason, GCC 8 did not issue warnings for all such comparisons.

InnoDB and XtraDB had redundant assertions for checking that
function parameters that were declared as nonnull were not NULL.

it was supposed to be `*(p-1)` not `*p-1`
(the crash happens if `*p==0`)