Need to call split_sum_func if an aggregate function is part of order by
or partition by clause so that we have the required fields inside the temporary
table, as all the fields inside the partition by and order by clause of the
window function needs to be there in the temp table used for window function
computation.

The issue here is that for a window function in the ORDER BY clause, we were not
creating an extra field in the temporary table for the window function
(which is contained in an expression).
So a call to split_sum_func is added to handle this case

Also we need to update all items that contain a window function
in the temp table during window function computation as filesort would need
these values to be updated to calculate the ORDER BY clause of the select.

For degenerate joins we may have JOIN::table_list as NULL, so instead
of using JOIN::top_join_tab_count use the function JOIN::exec_join_tab_cnt
to get the number of tables joined at the top level.

The accessor dtuple_get_nth_v_field() was defined differently between
debug and release builds in MySQL 5.7.8 in
mysql/mysql-server@c47e1751b742454de553937039bbf2bcbe3c6bc7
and a debug assertion to document or enforce the questionable assumption
tuple->v_fields == &tuple->fields[tuple->n_fields] was missing.

This was apparently no problem until MDEV-11369 introduced instant
ADD COLUMN to MariaDB Server 10.3. With that work present, in one
test case, trx_undo_report_insert_virtual() could in release builds
fetch the wrong value for a virtual column.

We replace many of the dtuple_t accessors with const-preserving
inline functions, and fix missing or misleadingly applied const
qualifiers accordingly.

log_checkpoint(), log_make_checkpoint_at(): Remove the parameter
write_always. It seems that the primary purpose of this parameter
was to ensure in the function recv_reset_logs() that both checkpoint
header pages will be overwritten, when the function is called from
the never-enabled function recv_recovery_from_archive_start().

create_log_files(): Merge recv_reset_logs() to its only caller.

Debug instrumentation: Prefer to flush the redo log, instead of
triggering a redo log checkpoint.

page_header_set_field(): Disable a debug assertion that will
always fail due to MDEV-19344, now that we no longer initiate
a redo log checkpoint before an injected crash.

In recv_reset_logs() there used to be two calls to
log_make_checkpoint_at(). The apparent purpose of this was
to ensure that both InnoDB redo log checkpoint header pages
will be initialized or overwritten.
The second call was removed (without any explanation) in MySQL 5.6.3:
mysql/mysql-server@4ca37968da54ddc6b3b6628f41428ddba1c79bb8

In MySQL 5.6.8 WL#6494, starting with
mysql/mysql-server@00a0ba8ad92569fcf08212b3b8cf046dc8a0ce10
the function recv_reset_logs() was not only invoked during
InnoDB data file initialization, but also during a regular
startup when the redo log is being resized.

mysql/mysql-server@45e91679832219e2593c77185342f11f85232b58
in MySQL 5.7.2 removed the UNIV_LOG_ARCHIVE code, but still
did not remove the parameter write_always.

Disable (hopefully temprorary) this check. Also add tests for some serialized
functions.

on tablespace files

Fix is to always add Full Control for NetworkService account, for every
file that copyback/moveback copies around.

If required privilege is missing, dump the output from "SHOW GRANTS"
into mariabackup log.

This will help troubleshooting, and make the bug reproducible.

The statement

SET GLOBAL innodb_encryption_rotate_key_age=0;

would have the unwanted side effect that ENCRYPTION=DEFAULT tablespaces
would no longer be encrypted or decrypted according to the setting of
innodb_encrypt_tables.

We implement a trigger, so that whenever one of the following is executed:

SET GLOBAL innodb_encrypt_tables=OFF;
SET GLOBAL innodb_encrypt_tables=ON;
SET GLOBAL innodb_encrypt_tables=FORCE;

all wrong-state ENCRYPTION=DEFAULT tablespaces will be added to
fil_system_t::rotation_list, so that the encryption will be added
or removed.

Note: This will *NOT* happen automatically after a server restart.
Before reading the first page of a data file, InnoDB cannot know
the encryption status of the data file. The statement
SET GLOBAL innodb_encrypt_tables will have the side effect that
all not-yet-read InnoDB data files will be accessed in order to
determine the encryption status.

innodb_encrypt_tables_validate(): Stop disallowing
SET GLOBAL innodb_encrypt_tables when innodb_encryption_rotate_key_age=0.
This reverts part of commit 50eb40a2
that addressed MDEV-11738 and MDEV-11581.

fil_system_t::read_page0(): Trigger a call to fil_node_t::read_page0().
Refactored from fil_space_get_space().

fil_crypt_rotation_list_fill(): If innodb_encryption_rotate_key_age=0,
initialize fil_system->rotation_list. This is invoked both on
SET GLOBAL innodb_encrypt_tables and
on SET GLOBAL innodb_encryption_rotate_key_age=0.

fil_space_set_crypt_data(): Remove.

fil_parse_write_crypt_data(): Simplify the logic.

This is joint work with Marko Mäkelä.

To read histograms for a table, we should check if the allocation of statistics was done or not,
if not done we should not try to read histograms for such a table.

to the patch for MDEV-17605

MDEV-17654 Incorrect syntax returned for column with CHECK constraint in the "SHOW CREATE TABLE ..." result

Prepend COMMENT before CHECK constraint in SHOW CREATE

Closes #924

The working directory, resource limits and core pattern will
aid the user finding a core file in the case of failure.

While the core file size is most relevant however other resource
limits may give a clue as the the cause of the fatal signal so
include them also.

As signal handler functions are limited, proc filesystem reads/
readlink calls are used instead of the more obvious getcwd/getrlimits
functions which aren't listed as signal safe.

Results in output of the form:

Writing a core file: working directory at /tmp/datadir
Resource Limits:
Limit                     Soft Limit           Hard Limit Units
Max cpu time              unlimited            unlimited seconds
Max file size             unlimited            unlimited bytes
Max data size             unlimited            unlimited bytes
Max stack size            8388608              unlimited bytes
Max core file size        unlimited            unlimited bytes
Max resident set          unlimited            unlimited bytes
Max processes             47194                47194 processes
Max open files            1024                 4096 files
Max locked memory         65536                65536 bytes
Max address space         unlimited            unlimited bytes
Max file locks            unlimited            unlimited locks
Max pending signals       47194                47194 signals
Max msgqueue size         819200               819200 bytes
Max nice priority         0                    0
Max realtime priority     0                    0
Max realtime timeout      unlimited            unlimited            us
Core pattern: |/usr/libexec/abrt-hook-ccpp %s %c %p %u %g %t %P %I

Segmentation fault (core dumped)

Closes #537

use s->fields instead of s->stored_fields. extra_null_bitmap is allocated in Table_triggers_list::prepare_record_accessors with respect to virtual fields, so it will not overflow

Closes #1292

MDEV-14572: Assertion `! is_set()' failed in Diagnostics_area::set_eof_status upon EXPLAIN UPDATE in PS

Restore EXPAIN flag in SELECT_LEX before execution multi-update by flag in LEX
(the same but in other way made before INSERT/DELETE/SELECT)

Without it, mysql_update() didn't know that there will be EXPLAIN result set and was sending OK at the end of the update, which conflicted with the EOF sent later by EXPLAIN.

The patch for MDEV-18738 fixed this problem. Adding tests only.

copy_if_not_alloced() did not handle situations when
"from" is a constant string pointing to a substring of "to",
so this code part freed "to" but then tried to copy its old (already freed)
content to a new buffer:

  if (to->realloc(from_length))
    return from;
  if ((to->str_length=MY_MIN(from->str_length,from_length)))
    memcpy(to->Ptr,from->Ptr,to->str_length);

Adding a new code piece that catches such constant substrings
and propery reallocs "to" to preserve its important part referenced
by "from".

This reverts commit 61f370a3
and implements a simpler fix that is straightforward to merge to 10.3.

lock_print_info: Renamed from PrintNotStarted. Dump the
entire contents of trx_sys->mysql_trx_list.

lock_print_info_rw_recovered: Like lock_print_info, but dump
only recovered transactions in trx_sys->rw_trx_list.

lock_print_info_all_transactions(): Dump both trx_sys->mysql_trx_list
and trx_sys->rw_trx_list.

TrxLockIterator, TrxListIterator, lock_rec_fetch_page(): Remove.
This is a partial backport of the 10.3
commit a447980f
which removed the race-condition-prone ability of the InnoDB monitor
to read relevant pages into the buffer pool for some record locks.

In InnoDB error messages, replace the hyperlink URLs to point
to the MariaDB knowledge base.

ut_list_validate(), ut_list_map(): Add variants with const Functor&
so that these functions can be called with an rvalue.

Remove wrapper macros, and add #ifdef UNIV_DEBUG around debug-only code.

MDEV-18429 Consistent non-locking reads do not appear in TRANSACTIONS section of SHOW ENGINE INNODB STATUS

lock_print_info_all_transactions(): print transactions which are started
but not in RW or RO lists.

print_not_started(): Replaces PrintNotStarted. Collect the skipped
transactions.

fil_node_t::read_page0(): Do not replace up-to-date metadata with a
possibly old version of page 0 that is being reread from the file.
A more up-to-date page 0 could still exists in the buffer pool,
waiting to be written back to the file.

BtrBulk::finish(): On error, the B-tree can be corrupted. Only upon
successful completion, it makes sense to validate the index.

This problem was earlier fixed, possibly by f8a800be
and is not repeatable in 10.1-10.4 any more. Adding tests only.

The 'SET server_audit_logging ' statements should be logged no matter
what.

Since this limit is imposed by the SHOW_VAR_FUNC_BUFF_SIZE, we just
launch the error message.