The test innodb.101_compatibility occasionally fails, because the flags
for the tables tdd and tp are not always converted back. Thus, the
second attempt of corrupting the flags will update garbage to garbage,
and cause test failure.

This started failing related to one or two MDEV-12266 commits affecting
the function fsp_flags_try_adjust().

fsp_flags_try_adjust(): If the file has not been opened (space->size==0),
try determining its size by reading the file. Only if the file is not
readable, give up.

Also, avoid dummy writes in the Perl script, and add some instrumentation.

- Adding "return true" into LEX::set_system_variable()
  and LEX::set_default_system_variable() after my_error().
  This makes the parser exit on error immediately.
  Previously, the error was caught only in mysql_parser(),
  a few lines after the parse_sql() call.
- Fixing "--error 1272" to "--error ER_VARIABLE_IS_NOT_STRUCT" in tests

log_write_up_to(): Erase the end of the current log block.
Simplify the computation of pad_size.

log_buffer_switch(): Evaluate a condition only once.

- recovered_lsn shouldn't be initialized during xtrabackup_copy_logfile().
If partial redo log read during the end of xtrabackup_copy_logfile() then
recovered_lsn will be different from scanned_lsn. Re-initialization of
recovered_lsn could lead to partial read again. It is a regression of
MDEV-14545

MDEV-10991: Server crashes in spider_udf_direct_sql_create_conn - tests in spider/oracle* suites crash the server

The fix for this bug was automatically merged from 10.1.  However, part of that
fix is unnecessary in 10.3.  This commit rolls back the part of the fix that is
unnecessary in 10.3.

Author:
  Jacob Mathew.

Reviewer:
  Kentoku Shiba.

           Item::derived_field_transformer_for_having

The crash occurred due to an inappropriate handling of multiple equalities
when pushing conditions into materialized views/derived tables. If equalities
extracted from a multiple equality can be pushed into a materialized
view/derived table they should be plainly conjuncted with other pushed
predicates rather than form a separate AND sub-formula.

- Adding class Field_int as a common
  parent for Field_{longlong|long|short|medium|tiny}
- Moving store_decimal(), val_decimal(), get_date(), store_time_dec(),
  get_date(), val_bool() from Field_num to Field_int
- Adding Field_int::val_str_from_long() and reusing it in
  Field_tiny::val_str(), Field_short::val_str(), Field_medium::val_str()
  and Field_long::val_str(). This removes a good amount of duplicate code
- Adding "const" qualifier to "virtual bool Field::optimize_range()".

Handle overlaping "from" and Field_blob_compressed::value for compressed
blobs similarily to regular blobs.

MDEV-14831 CREATE OR REPLACE SEQUENCE under LOCK TABLE corrupts the
sequence, causes ER_KEY_NOT_FOUND

The problem was that sequence_insert didn't properly handle the case
where there where there was a LOCK TABLE while creating the sequence.

Fixed by opening the sequence table, for inserting the first record, in
a new environment without any other open tables.

Found also a bug in Locked_tables_list::reopen_tables() where the lock
structure for the new tables was allocated in THD::mem_root, which causes
crashes. This could cause problems with other create tables done under
LOCK TABLES.

Use high accuracy timer on Windows 8.1+ for system versioning,it needs
accurate high resoution start query time.

Continue to use the inaccurate (but much faster timer function)
GetSystemTimeAsFileTime() where accuracy does not matter, e.g in
set_timespec_time_nsec(),or my_time()

concurrently.

There is a deadlock between

C1 mariabackup's connection that holds MDL locks
C2 Online ALTER TABLE that wants to have MDL exclusively
   and tries to upgrade its mdl lock.
C3 another mariabackup's connection that does FLUSH TABLES (or FTWRL)

C3 waits waits for C2,  which waits for C1, which waits for C3,
thus the deadlock.


MDL locks cannot be released until FLUSH  succeeds, because
otherwise it would allow ALTER to sneak in, causing backup to abort and
breaking lock-ddl-per-table's promise.

The fix here workarounds the deadlock, by killing connections in
"Waiting for metadata lock" status (i.e ALTER). This killing continues
until FTWRL succeeds.

Killing connections is skipped in case --no-locks parameter
was  passed to backup, because there won't be a FLUSH.

For the reference,in Percona's xtrabackup --lock-ddl-per-connection
silently implies --no-lock ie FLUSH is always skipped there.

A rather large part of fix is introducing DBUG capability to start
a query  the new connection at the right moment of backup
compensating somewhat for mariabackup' lack of send_query or DBUG_SYNC.

This reverts commit d2660362.
The patch would cause a crash when DROP TABLE is executed
and the .ibd file is missing. It is not easy to fix this;
there is some delicate logic in fil_space_get_page_size().

btr_free_root_check(), btr_free_if_exists():
Replace page_id, page_size with fil_space_t* and the
root page number.

btr_free_but_not_root(): Take fil_space_t* as a parameter,
or NULL if the operation is not going to be redo-logged.

btr_free(): Pass space=NULL to btr_free_but_not_root().

this is a 10.3 version of 27d94b7e

It disables caching of the first argument of IN,
if it's of a temporal type. Because other types are not
cached in this context.

this is a 10.3 version of 1c6f6dc8

this is a 10.3 version of 885edc4f

reorder items in args[] array. Instead of

  when1,then1,when2,then2,...[,case][,else]

sort them as

  [case,]when1,when2,...,then1,then2,...[,else]

in this case all items used for comparison take a continuous part
of the array and can be aggregated directly. and all items that
can be returned take a continuous part of the array and can be
aggregated directly. Old code had to copy them to a temporary
array before aggreation, and then copy back (thd->change_item_tree)
everything that was changed.

this is a 10.3 version of bf1ca14f

fil_space_for_table_exists_in_mem(): Fix a regression that was
introduced in commit 05863142
when removing fil_system.name_hash. The condition
!valid || space == fnamespace
was incorrectly replaced with !valid, instead of true.

fil_report_missing_tablespace(): Merge to the only caller.

Introduced new status variable for custom aggregate functions.

InnoDB always keeps all tablespaces in the fil_system cache.
The fil_system.LRU is only for closing file handles; the
fil_space_t and fil_node_t for all data files will remain
in main memory. Between startup to shutdown, they can only be
created and removed by DDL statements. Therefore, we can
let dict_table_t::space point directly to the fil_space_t.

dict_table_t::space_id: A numeric tablespace ID for the corner cases
where we do not have a tablespace. The most prominent examples are
ALTER TABLE...DISCARD TABLESPACE or a missing or corrupted file.

There are a few functional differences; most notably:
(1) DROP TABLE will delete matching .ibd and .cfg files,
even if they were not attached to the data dictionary.
(2) Some error messages will report file names instead of numeric IDs.

There still are many functions that use numeric tablespace IDs instead
of fil_space_t*, and many functions could be converted to fil_space_t
member functions. Also, Tablespace and Datafile should be merged with
fil_space_t and fil_node_t. page_id_t and buf_page_get_gen() could use
fil_space_t& instead of a numeric ID, and after moving to a single
buffer pool (MDEV-15058), buf_pool_t::page_hash could be moved to
fil_space_t::page_hash.

FilSpace: Remove. Only few calls to fil_space_acquire() will remain,
and gradually they should be removed.

mtr_t::set_named_space_id(ulint): Renamed from set_named_space(),
to prevent accidental calls to this slower function. Very few
callers remain.

fseg_create(), fsp_reserve_free_extents(): Take fil_space_t*
as a parameter instead of a space_id.

fil_space_t::rename(): Wrapper for fil_rename_tablespace_check(),
fil_name_write_rename(), fil_rename_tablespace(). Mariabackup
passes the parameter log=false; InnoDB passes log=true.

dict_mem_table_create(): Take fil_space_t* instead of space_id
as parameter.

dict_process_sys_tables_rec_and_mtr_commit(): Replace the parameter
'status' with 'bool cached'.

dict_get_and_save_data_dir_path(): Avoid copying the fil_node_t::name.

fil_ibd_open(): Return the tablespace.

fil_space_t::set_imported(): Replaces fil_space_set_imported().

truncate_t: Change many member function parameters to fil_space_t*,
and remove page_size parameters.

row_truncate_prepare(): Merge to its only caller.

row_drop_table_from_cache(): Assert that the table is persistent.

dict_create_sys_indexes_tuple(): Write SYS_INDEXES.SPACE=FIL_NULL
if the tablespace has been discarded.

row_import_update_discarded_flag(): Remove a constant parameter.

fsp_get_available_space_in_free_extents(): Declare the function static
in the only caller, and take const fil_space_t& as a parameter.

fil_space_get_by_name(): Remove.
(Implement differently in mariabackup.)

fil_ibd_open(): Check if the tablespace by the same ID already
exists. If it is the same name, return success, else failure.

trx_rsegf_get(), trx_undo_get_first_rec(): Change the parameter to
fil_space_t* so that fewer callers need to be adjusted.

trx_undo_free_page(): Remove the redundant parameter 'space'.

Remove the parameter page_size, and pass a dummy page size
to buf_page_get_gen() along with BUF_PEEK_IF_IN_POOL.

fil_discard_tablespace(): Merge to row_discard_tablespace()
which was the only caller.

fil_recreate_table(), fil_recreate_tablespace(),
fil_reinit_space_header_for_table(): Move the functions
to the only calling module and declare static.

fil_recreate_table(): Remove the constant parameter space_id=0,flags.