dict_table_t::init_instant(): Initialize instant->non_pk_col_map[].
Refactored from dict_table_t::instant_column().
Also, assert that the n_nullable for the clustered index is initialized
correctly.

dict_col_t::same_format(): Check if two columns have the same
data type and compatible length.

Allow instant changes of columns in ROW_FORMAT=REDUNDANT
from NOT NULL to NULL.

Later, this may be implemented for ROW_FORMAT=COMPACT or DYNAMIC,
but in that case any indexes on the table must be rebuilt.

dict_table_t::prepare_instant(): Add some debug assertions,
and relax a debug assertion so that the number of fields is
allowed not to change.

dict_index_t::instant_add_field(): Relax a debug assertion,
allowing a column to change from NOT NULL to NULL.

dict_table_t::instant_column(): Add debug assertions.

instant_alter_column_possible(): Allow ALTER_COLUMN_NULLABLE
when applicable.

innodb_insert_sys_columns(): Add the parameter bool update=false
to run UPDATE instead of INSERT.

innobase_instant_add_col(): Remove; let the only caller invoke
innodb_insert_sys_columns() directly.

innobase_instant_try(): Update the SYS_COLUMNS record if the
column is changed. Only convert the table to the instant ALTER TABLE
format if necessary. For ALTER_COLUMN_NULLABLE in ROW_FORMAT=REDUNDANT,
there is no data format change.

Remove the bug-compatible crc32 algorithm variant that was added
to allow an upgrade from data files from big-endian systems where
innodb_checksum_algorithm=crc32 was used on MySQL 5.6
or MariaDB 10.0 or 10.1.

Affected users should be able to recompute page checksums using
innochecksum.

With innodb_default_row_format=redundant, InnoDB would crash when
using table options that are incompatible with ROW_FORMAT=REDUNDANT.

create_table_info_t::m_default_row_format: Cache the value of
innodb_default_row_format.

create_table_info_t::check_table_options(): Validate ROW_TYPE_DEFAULT
with m_default_row_format.

create_table_info_t::innobase_table_flags(): Use the
cached m_default_row_format.

create_table_info_t: Never read m_form->s->row_type.
Use m_create_info->row_type instead.

dict_tf_set(): Never set invalid flags for ROW_FORMAT=REDUNDANT.

ha_innobase::truncate(): Set info.row_type based on the ROW_FORMAT
of the current table.

In MySQL 5.7, it was noticed that files are not portable between
big-endian and little-endian processor architectures
(such as SPARC and x86), because the original implementation of
innodb_checksum_algorithm=crc32 was not byte order agnostic.

A byte order agnostic implementation of innodb_checksum_algorithm=crc32
was only added to MySQL 5.7, not backported to 5.6. Consequently,
MariaDB Server versions 10.0 and 10.1 only contain the CRC-32C
implementation that works incorrectly on big-endian architectures,
and MariaDB Server 10.2.2 got the byte-order agnostic CRC-32C
implementation from MySQL 5.7.

MySQL 5.7 introduced a "legacy crc32" variant that is functionally
equivalent to the big-endian version of the original crc32 implementation.
Thanks to this variant, old data files can be transferred from big-endian
systems to newer versions.

Introducing new variants of checksum algorithms (without introducing
new names for them, or something on the pages themselves to identify
the algorithm) generally is a bad idea, because each checksum algorithm
is like a lottery ticket. The more algorithms you try, the more likely
it will be for the checksum to match on a corrupted page.

So, essentially MySQL 5.7 weakened innodb_checksum_algorithm=crc32,
and MariaDB 10.2.2 inherited this weakening.

We introduce a build option that together with MDEV-17957
makes innodb_checksum_algorithm=strict_crc32 strict again
by only allowing one variant of the checksum to match.

WITH_INNODB_BUG_ENDIAN_CRC32: A new cmake option for enabling the
bug-compatible "legacy crc32" checksum. This is only enabled on
big-endian systems by default, to facilitate an upgrade from
MariaDB 10.0 or 10.1. Checked by #ifdef INNODB_BUG_ENDIAN_CRC32.

ut_crc32_byte_by_byte: Remove (unused function).

legacy_big_endian_checksum: Remove. This variable seems to have
unnecessarily complicated the logic. When the weakening is enabled,
we must always fall back to the buggy checksum.

buf_page_check_crc32(): A helper function to compute one or
two CRC-32C variants.

Also, apply the MDEV-17957 changes to encrypted page checksums,
and remove error message output from the checksum function,
because these messages would be useless noise when mariabackup
is retrying reads of corrupted-looking pages, and not that
useful during normal server operation either.

The error messages in fil_space_verify_crypt_checksum()
should be refactored separately.

This is a backport of a part of
commit 18455ec3
from 10.1.

Problem:

  Innodb_checksum_algorithm checks for all checksum algorithm to
validate the page checksum even though the algorithm is specified as
strict_crc32, strict_innodb, strict_none.

Fix:

   Remove the checks for all checksum algorithm to validate the page
checksum if the algo is specified as strict_* values.

The Microsoft compiler only allows function attributes before the
function signature, not after it.

1. don't run full mysql_upgrade on every server restart,
   use --version-check to do it only once

2. fix syslog tag name in the postinst script, don't pretend
   mysqld_safe generated all these messages. Auto-detect the version
   to simplify maintenance

ha_innobase::truncate(): Because CREATE TEMPORARY TABLE
allows invalid table options when innodb_file_per_table=1,
do allow them also in TRUNCATE for temporary tables.

This is fixing a regression that was introduced in MDEV-15562
commit 0e5a4ac2.

On rollback of UPDATE or DELETE of a ROW_FORMAT=COMPRESSED table,
page_zip_write_trx_id_and_roll_ptr() was accessing
offsets=offsets_ after offsets_ went out of scope.

Current implementation is conflicting. If UNICODE is defined, FormatMessage() will be FormatMessageW(), and variable win_errormsg with type char can not be passed to it, which should be changed to TCHAR instead. Since we don't use UNICODE here, we can use FormatMessageA() directly to avoid conversion error.
```
my_global.h(1092): error C2664: 'DWORD FormatMessageW(D
WORD,LPCVOID,DWORD,DWORD,LPWSTR,DWORD,va_list *)' : cannot convert argument 5 from 'char [2048]' to 'LPWSTR'
```

References to global symbols prevent InnoDB from being built as a
dynamic plugin on Windows.

Refer to CHARSET_INFO::number, because that is what InnoDB is already
persistently storing in its data dictionary.

btr_node_ptr_max_size(): Treat CHAR(0) from SQL as a special case.
The InnoDB internal SQL parser maps the type "CHAR" to DATA_VARCHAR,
but MariaDB does allow CHAR(0) with an empty value, and does enforce
the length limitation.

keyinfo->name is a LEX_CSTRING

also, fix the location comment (that applied to ext_key_part_map)

btr_cur_pessimistic_insert(): Convert the metadata field of the metadata
record into BLOB before inserting, just like btr_cur_optimistic_insert()
does.

MDEV-17968 Error 174 "Fatal error during initialization of handler" from storage engine Aria upon DELETE from partitioned table

The correct title is:
MDEV-17972 Assertion `is_valid_value_slow()' failed in Datetime::Datetime

MDEV-17968 Error 174 "Fatal error during initialization of handler" from storage engine Aria upon DELETE from partitioned table

--echo # MDEV-17979 Assertion `0' failed in Item::val_native upon SELECT with timestamp, NULLIF, GROUP BY
--echo #