Fixed by adding table flag HA_WANTS_PRIMARY_KEY, which is like
HA_REQUIRE_PRIMARY_KEY but tells SQL upper layer that the storage engine
internally can handle tables without primary keys (for example for
sequences or trough user variables)

- Use the correct range bounds when doing a reverse-ordered range scan
  (this was already done for HA_READ_PREFIX_LAST_OR_PREV but not for
  HA_READ_BEFORE_KEY).

MDEV-17542 10.3: gcc-8.0 produces lots of -Wclass-memaccess warnings in Table_scope_and_contents_source_st

Problem description and workaround are here
https://developercommunity.visualstudio.com/content/problem/185399/error-c2760-in-combaseapih-with-windows-sdk-81-and.html

On the hidden metadata record, if instant ALTER TABLE was executed
multiple times on the same table, purge could fail to reset the
DB_TRX_ID,DB_ROLL_PTR on the updated metadata record. This is
only a cosmetic failure that was caught (and separately fixed)
in 10.4 during the MDEV-15562 development. The problem was that
occasionally, innodb.instant_alter_crash would fail with a
result difference due to the DB_TRX_ID,DB_ROLL_PTR not having
been reset on the metadata record.

This bug should have no noticeable impact, because the metadata
record is invisible to the SQL layer, and never subjected to
MVCC or locking.

I was unable to repeat the problem on 10.3.

row_purge_parse_undo_rec(): Set node->ref for the metadata record.

In addition,don't remove datadir if it was not created or was not empty.

This reverts commit 2d4075e1
where the debug assertion was added. There seems to be a potential
problem in the purge of indexes that depend on virtual columns.

Ultimately, we should change the InnoDB undo log format so that
all actual secondary index keys are stored there, also for
virtual or spatial indexes. In that way, purge and rollback would
be more straightforward.

On Windows, a mismatch between TIMETPF ("%ld") and time_t would be reported.
Use "%ld" and long, like the code used to be.

row_ins_clust_index_entry_low(): Do not call dtuple_t::trim()
before row_ins_clust_index_entry_by_modify(), so that the values
of all columns will be available in row_upd_build_difference_binary().
If applicable, the tuple can be trimmed in btr_cur_optimistic_update()
or btr_cur_pessimistic_update(), which will be called by
row_ins_clust_index_entry_by_modify().

The setting innodb_safe_truncate=ON reduces compatibility with older
versions of MariaDB and backup tools in two ways.

First, we will be writing TRX_UNDO_RENAME_TABLE records, which older
versions do not know about. These records could be misinterpreted if
a DDL transaction was recovered and would be rolled back.
Such rollback is only possible if the server was killed while
an incomplete DDL transaction was persisted. On transaction completion,
the insert_undo log pages would only be repurposed for new undo log
allocations, and their contents would not matter. So, older versions
will not have a problem with innodb_safe_truncate=ON if the server was
shut down cleanly.

Second, to prevent such recovery failure, innodb_safe_truncate=ON will
cause a modification of the redo log format identifier, which will
prevent older versions from starting up after a crash. MariaDB Server
versions older than 10.2.13 will refuse to start up altogether, even
after clean shutdown.

A server restart with innodb_safe_truncate=OFF will restore compatibility
with older server and backup versions.

Added only test case because the bug was fixed by the patch for mdev-17382.

Added only test case because the bug was fixed by the patch for mdev-16992.

The syntax error happened because we had not implemented a different print for
percentile functions. The syntax is a bit different when we use percentile functions
as window functions in comparision to normal window functions.
Implemented a seperate print function for percentile functions

Opened up MYSQL_TYPE _DATETIME{,2} <-> _NEWDATE conversions for replication.

row_build_index_entry_low(): Assert that when the value of a
virtual column is not available, this can only happen when
the index creation was completed but not committed yet.

This change is not fixing any bug, making a debug assertion
stricter, so that bugs can be caught in the future.

Ultimately, we should change the InnoDB undo log format so that
all actual secondary index keys are stored there, also for
virtual or spatial indexes. In that way, purge and rollback would
be more straightforward.

           in Field_iterator_table::create_item

When IN predicate is converted to IN subquery we have to ensure that
any item from the select list of the subquery has some name and this name
is unique across the select list.
This was not guaranteed by the code before the patch for MDEV-17222.
If the name of an item of the select list was not set, and this happened
for binary constants, then the server crashed. If the first row in the IN
list contained the same constant in two different positions then the server
returned an error message.
This was fixed by providing all constants in the first row of the IN list
with generated names.

When we have a query which has implicit_grouping then we are sure that we would end up with only one
row so there is no point to do DISTINCT computation

The failure caused by MDEV-16387

           upon INSERT .. SELECT

The function Item *Item_direct_view_ref::derived_field_transformer_for_where()
erroneously did not strip off ref wrappers from references to materialized
derived tables / views. As a result the expressions that contained some
references of the type Item_direct_view_ref to columns of a materialized
derived table / view V were pushed into V incorrectly. This could cause
crashes for some INSERT ... SELECT statements.

disable rpl_mdev382 on Windows, due to unix shell escaping used there.

Bump mysqldump to a version greater than that on the 10.3 branch.

A prepared backup from Mariabackup does not really need to contain any
redo log file, because all log will have been applied to the data files.

When the user copies a prepared backup to a data directory (overwriting
existing files), it could happen that the data directory already contained
redo log files from the past. mariabackup --copy-back) would delete the
old redo log files, but a user’s own copying script might not do that.
To prevent corruption caused by mixing an old redo log file with data
files from a backup, starting with MDEV-13311, Mariabackup would create
a zero-length ib_logfile0 that would prevent startup.

Actually, there is no need to prevent InnoDB from starting up when a
single zero-length file ib_logfile0 is present. Only if there exist
multiple data files of different lengths, then we should refuse to
start up due to inconsistency. A single zero-length ib_logfile0 should
be treated as if the log files were missing: create new log files
according to the configuration.

open_log_file(): Remove. There is no need to open the log files
at this point, because os_file_get_status() already determined
the size of the file.

innobase_start_or_create_for_mysql(): Move the creation of new
log files a little later, not when finding out that the first log
file does not exist, but after finding out that it does not exist
or it exists as a zero-length file.

Rename the 10.2-specific configuration option innodb_unsafe_truncate
to innodb_safe_truncate, and invert its value.

The default (for now) is innodb_safe_truncate=OFF, to avoid
disrupting users with an undo and redo log format change within
a Generally Available (GA) release series.