On MIPS platforms (and probably others) unaligned memory access results in a
bus error. In the connect storage engine, block data for some data formats is
stored packed in memory and the TYPBLK class is used to read values from it.
Since TYPBLK does not have special handling for this packed memory, it can
quite easily result in unaligned memory accesses.

The simple way to fix this is to perform all accesses to the main buffer
through memcpy. With GCC and optimizations turned on, this call to memcpy is
completely optimized away on architectures where unaligned accesses are ok
(like x86).

Contributors:
James Cowgill <jcowgill@debian.org>

Some architectures (mips) require libatomic to support proper
atomic operations. Check first if support is available without
linking, otherwise use the library.

Contributors:
James Cowgill <jcowgill@debian.org>
Jessica Clarke <jrtc27@debian.org>
Vicențiu Ciorbaru <vicentiu@mariadb.org>

Cherry-picking the fix for MDEV-19866 changes the behavior of
the Spider slightly. So, I modified a existing test to match
the new behavior.

MDEV-19866 With a Spider table, a SELECT with WHERE involving primary key breaks following SELECTs (#1356)

Change checking scanning partitions from part_spec to part_info->read_partitions

In commit 1cb218c3 (MDEV-26450)
we introduced the function log_write_and_flush(), which may
compete with log_checkpoint() invoking log_write_flush_to_disk_low()
from another thread.

The assertion n_pending_flushes==1 is too strict.
There is no possibility of a race condition here, because
fil_flush() is protected by fil_system->mutex and the
rest will be protected by log_sys->mutex.

log_write_flush_to_disk_low(), log_write_and_flush():
Relax the assertions to test for a nonzero count.

Also fixes MDEV-24467 Memory not freed after failed INSERT DELAYED

Description:

In case of an error (e.g. data truncation) during mysql_insert()
handling an INSERT DELAYED, the data type specific data in
fields (e.g. Field_blob::value) is not taken over by the delayed
writer thread.

All fields in table_list->table are freed by free_root()
immediately after mysql_insert(). To avoid a memory leak,
we need to free the specific data before exiting mysql_insert()
on error.

The crash happened because my_isalnum() does not support character
sets with mbminlen>1.

The value of "ft_boolean_syntax" is converted to utf8 in do_string_check().
So calling my_isalnum() is combination with "default_charset_info" was wrong.

Adding new parameters (size_t length, CHARSET_INFO *cs) to
ft_boolean_check_syntax_string() and passing self->charset(thd)
as the character set.

The crash happened because Item_aes_crypt::val_str() did not
set the character set of the result.

Co-authored-by: FX Coudert <fxcoudert@gmail.com>

Uninitialized ref_pointer_array[] because setup_fields() got empty
fields list.  mysql_multi_update() for some reason does that by
substituting the fields list with empty total_list for the
mysql_select() call (looks like wrong merge since total_list is not
used anywhere else and is always empty). The fix would be to return
back the original fields list. But this fails update_use_source.test
case:

  --error ER_BAD_FIELD_ERROR
  update v1 set t1c1=2 order by 1;

Actually not failing the above seems to be ok.

The other fix would be to keep resolve_in_select_list false (and that
keeps outer context from being resolved in
Item_ref::fix_fields()). This fix is more consistent with how SELECT
behaves:

  --error ER_SUBQUERY_NO_1_ROW
  select a from t1 where a= (select 2 from t1 having (a = 3));

So this patch implements this fix.

There are two fill_record() functions (lines 8343 and 8618). First one
is used when there are some explicit values, the second one is used
for all implicit values. First one does update_default_fields(), the
second one did not. Added update_default_fields() call to the implicit
version of fill_record().

Second alter subcommand correctly removed VERS_ROW_END flag. We throw
ER_VERS_PERIOD_COLUMNS in such case.

- Cleaned up Vers_parse_info::check_sys_fields();
- Renamed VERS_SYS_START_FLAG, VERS_SYS_END_FLAG to VERS_ROW_START,
  VERS_ROW_END.

If error_reported is not set upper caller open_table_from_share()
throws error ER_NOT_FORM_FILE itself via open_table_error().

On deadlock transaction is rolled back (and trx->state is cleared) but
SELECT continued the loop because evaluate_join_record() ignored the
error status returned from lower join evaluation. val_int() does not
return error status so it is checked by thd->is_error().

Test case was created by Thirunarayanan Balathandayuthapani
<thiru@mariadb.com>

In commit 3690c549
this test was not adjusted.

This is a documentation-only patch to refine the description of
binary mode for the mariadb client.

Reviewed By:
============
Andrei Elkin <andrei.elkin@mariadb.com>

Note: This patch backports commits 10cd2818 and 1755ea4b from 10.3.

10cd2818:
Problem:- Some binary data is inserted into the table using
Jconnector. When binlog dump of the data is applied using mysql
client it gives syntax error.

Reason:-
After investigating it turns out to be a issue of mysql client not
able to properly handle  \\0 <0 in binary>. In all binary files
where mysql client fails to insert
these 2 bytes are common (0x5c00)

Solution:-
I have changed mysql.cc to include for the possibility that binary
string can have \\0 in it

1755ea4b:
Changes on top of Sachin’s patch. Specifically:
 1) Refined the parsing break condition to only change the parser’s
behavior for parsing strings in binary mode (behavior of \0 outside
of strings is unchanged).
 2) Prefixed binary_zero_insert.test with ‘mysql_’ to more clearly
associate the  purpose of the test.
 3) As the input of the test contains binary zeros (0x5c00),
different text editors can visualize this sequence differently, and
Github would not display it at all. Therefore, the input itself was
consolidated into the test and created out of hex sequences to make
it easier to understand what is happening.
 4) Extended test to validate that the rows which correspond to the
INSERTS with 0x5c00 have the correct binary zero data.

Reviewed By:
============
Andrei Elkin <andrei.elkin@mariadb.com>

Changes on top of Sachin’s patch. Specifically:
 1) Refined the parsing break condition to only change the parser’s
behavior for parsing strings in binary mode (behavior of \0 outside
of strings is unchanged).
 2) Prefixed binary_zero_insert.test with ‘mysql_’ to more clearly
associate the  purpose of the test.
 3) As the input of the test contains binary zeros (0x5c00),
different text editors can visualize this sequence differently, and
Github would not display it at all. Therefore, the input itself was
consolidated into the test and created out of hex sequences to make
it easier to understand what is happening.
 4) Extended test to validate that the rows which correspond to the
INSERTS with 0x5c00 have the correct binary zero data.

Reviewed By:
===========
Andrei Elkin <andrei.elkin@mariadb.com>

Problem:- Some binary data is inserted into the table using Jconnector. When
binlog dump of the data is applied using mysql cleint it gives syntax error.

Reason:-
After investigating it turns out to be a issue of mysql client not able to properly
handle  \\\0 <0 in binary>. In all binary files where mysql client fails to insert
these 2 bytes are commom (0x5c00)

Solution:-
I have changed mysql.cc to include for the possibility that binary string can
have \\\0 in it

If a table has no unique indexes, write set key information will be collected on all columns in the table.
The write set key information has space only for max 3500 bytes for individual column, and if a varchar colummn of such non-primary key table is longer than
 this limit, currently a crash follows.
The fix in this commit, is to truncate key values extracted from such long varhar columns to max 3500 bytes.
This may potentially lead to false positive certification failures for transactions, which operate on separate cluster nodes, and update/insert/delete table rows, which differ only in the part of such long columns after 3500 bytes border.
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>

Normally we disable caching of routines in "SHOW CREATE".
Introduce an exception, if debug_dbug="+d,cache_sp_in_show_create".
lock_sync.test needs a way to populate the cache without side effects,
or else it runs into debug_sync timeouts.

So, this possibility to cache will be remain only for very special tests.

Occasionally, after restart, additional transactions will have been
executed, possibly related to innodb_stats_auto_recalc.

We should only care that the transaction ID sequence does
not go backwards.

Apparently, slow shutdown is not necessary anymore after MDEV-15912 fix

Let us mask the actual values of the defragmentation-related fields,
because they may vary. Also, remove the dependency on purge,
and instead delete records by a ROLLBACK of INSERT.

The reason for this behavior is that SP get cached, per connection.
The stored_program_cache is size of this cache, which amounts to 256
routines by default. A compiled stored procedure can easily be several
megabytes in size. Thus calling SHOW CREATE PROCEDURE for all stored
procedures, like mysqldump does, can require significant amount of memory.

Fixed by bypassing the cache for "SHOW CREATE". This should normally be
fine also perfomance-wise, as cache is meant to be used for repeated
execution, not repeated SHOW CREATEs.

Added a test to verify that CREATE PROCEDURE + SHOW CREATE PROCEURE do not
cache, i.e amount of allocated memory does not change.

Note, there is a change in existing behavior in an edge case :
If "SHOW CREATE PROCEDURE p1" called from p1, after p1 was altered, now
this will now return altered code. Previour behavior - relied on caching
and would return old code. The previous behavior might was not necessarily
correct.

Use in_sum_func (and so nest_level) only in LEX to which SELECT lex belong to

Reduce usage of current_select (because it does not always point on the correct
 SELECT_LEX, for example with prepare.

Change context for all classes inherited from Item_ident (was only for Item_field) in case of pushing down it to HAVING.

Now name resolution context have to have SELECT_LEX reference if the context is present.

Fixed feedback plugin stack usage.

Revert 88a4be75 and
9d97f92f, which had been
prematurely pushed by accident.

last commit  8221708e removed too much,
mtr is failing