Relax a too strict debug assertion, and add a test.

Allow DROP TABLE `#mysql50##sql-...._.` to drop tables that were
being rebuilt by ALGORITHM=INPLACE

NOTE: If the server is killed after the table-rebuilding ALGORITHM=INPLACE
commits inside InnoDB but before the .frm file has been replaced, then
the recovery will involve something else than DROP TABLE.

NOTE: If the server is killed in a true inplace ALTER TABLE commits
inside InnoDB but before the .frm file has been replaced, then we
are really out of luck. To properly handle that situation, we would
need a transactional mysql.ddl_fixup table that directs recovery to
rename or remove files.

prepare_inplace_alter_table_dict(): Use the altered_table->s->table_name
for generating the new_table_name.

table_name_t::part_suffix: The start of the partition name suffix.

table_name_t::dbend(): Return the end of the schema name.

table_name_t::dblen(): Return the length of the schema name, in bytes.

table_name_t::basename(): Return the name without the schema name.

table_name_t::part(): Return the partition name, or NULL if none.

row_drop_table_for_mysql(): Assert for #sql, not #sql-ib.

rec_get_offsets_func(): Relax a bogus debug assertion.
It would fail when we are operating on a copied prefix
of a node pointer record.

row_log_table_apply_op(): Remove references to dict_table_t::n_vcols.
Virtual column information is no longer being written to the log.

row_log_t: Remove the unused fields n_old_col, n_old_vcol.

MDEV-13723: Server crashes in ha_heap::find_unique_row or Assertion `0' failed in st_select_lex_unit::optimize with INTERSECT

With INTERSECT/EXCEPT fact that subquery item of IN/ALL/ANY was not assigned value does not mean that temporary table used for calculating unit is empty (records could be deleted).

When MySQL 5.7 introduced indexed virtual columns, it introduced
several bugs into the online table-rebuilding ALTER, that is,
the row_log_table_apply() family of functions.

The online_log format that was introduced for online table-rebuilding
ALTER in MySQL 5.6 should be sufficient. Ideally, any indexed virtual
column values would be evaluated based on the log records in the temporary
file. There is no need to log virtual column values.

(For ADD INDEX, that is row_log_apply(), we always must log the values of
the keys, no matter if the columns are virtual.)

Because omitting the virtual column values removes any chance of
row_log_table_apply() working with indexed virtual columns, we
will for now refuse LOCK=NONE in table-rebuilding ALTER operations
when indexes on virtual columns exist. This restriction would be
lifted in MDEV-14341.

innobase_indexed_virtual_exist(): New predicate, to determine if
indexed virtual columns exist in a table definition.

ha_innobase::check_if_supported_inplace_alter(): Refuse online rebuild
if indexed virtual columns exist.

rec_get_converted_size_temp_v(), rec_convert_dtuple_to_temp_v(): Remove.

row_log_table_delete(), row_log_table_update(, row_log_table_insert():
Remove parameters for virtual columns.

trx_undo_read_v_rows(): Remove the col_map parameter.

row_log_table_apply(): Do not deal with virtual columns.

Conflicts:
	mysql-test/r/cte_recursive.result
	mysql-test/r/derived_cond_pushdown.result
	mysql-test/t/cte_recursive.test
	mysql-test/t/derived_cond_pushdown.test
	sql/datadict.cc
	sql/handler.cc

MDEV-14333 Mariabackup --apply-log-only crashes if incomplete transactions with update_undo logs are present

trx_undo_free_prepared(): Relax the assertion for
mariabackup --apply-log-only.

MDEV-14164: Unknown column error when adding aggregate to function in oracle style procedure FOR loop

Make differentiation between pullout for merge and pulout of outer field during exists2in transformation.
In last case the field was outer and so we can safely start from name resolution context of the SELECT where it was pulled.
Old behavior lead to inconsistence between list of tables and outer name resolution context (which skips one SELECT for merge purposes) which creates problem vor name resolution.

Recording mtr.add_suppression("Could not use .*")
instead of mtr.add_suppression("Could not open .*")
in tests:
- binlog_encryption.rpl_binlog_errors
- binlog_encryption.binlog_index

There was a problem in the recent patch for MDEV-10817:
get_date() must "return true" on null_value rather than "return 0"

(forgot to fix Item_sum_hybrid::get_date() after copying and pasting
from Item_sum_hybrid::val_str()).

FlushObserver::flush(): Never discard unwritten changes.
We do not want to risk corrupting the system tablespace
or .ibd files that are not part of a table-rebuilding ALTER.

Ever since MDEV-10813 cleaned up InnoDB use of atomic memory operations
and made buf_block_fix() an atomic operation, some conditions around
buf_block_fix() have been unnecessary.

This problem was earlier fixed by the patch for MDEV-8910. Adding tests only.

The bug was fixed by the patch for the bug mdev-13780.

With a big buffer pool that contains many data pages,
DISCARD TABLESPACE took a long time, because it would scan the
entire buffer pool to remove any pages that belong to the tablespace.
With a large buffer pool, this would take a lot of time, especially
when the table-to-discard is empty.

The minimum amount of work that DISCARD TABLESPACE must do is to
remove the pages of the to-be-discarded table from the
buf_pool->flush_list because any writes to the data file must be
prevented before the file is deleted.

If DISCARD TABLESPACE does not evict the pages from the buffer pool,
then IMPORT TABLESPACE must do it, because we must prevent pre-DISCARD,
not-yet-evicted pages from being mistaken for pages of the imported
tablespace.

It would not be a useful fix to simply move the buffer pool scan to
the IMPORT TABLESPACE step. What we can do is to actively evict those
pages that could be mistaken for imported pages. In this way, when
importing a small table into a big buffer pool, the import should
still run relatively fast.

Import is bypassing the buffer pool when reading pages for the
adjustment phase. In the adjustment phase, if a page exists in
the buffer pool, we could replace it with the page from the imported
file. Unfortunately I did not get this to work properly, so instead
we will simply evict any matching page from the buffer pool.

buf_page_get_gen(): Implement BUF_EVICT_IF_IN_POOL, a new mode
where the requested page will be evicted if it is found. There
must be no unwritten changes for the page.

buf_remove_t: Remove. Instead, use trx!=NULL to signify that a write
to file is desired, and use a separate parameter bool drop_ahi.

buf_LRU_flush_or_remove_pages(), fil_delete_tablespace():
Replace buf_remove_t.

buf_LRU_remove_pages(), buf_LRU_remove_all_pages(): Remove.

PageConverter::m_mtr: A dummy mini-transaction buffer

PageConverter::PageConverter(): Complete the member initialization list.

PageConverter::operator()(): Evict any 'shadow' pages from the
buffer pool so that pre-existing (garbage) pages cannot be mistaken
for pages that exist in the being-imported file.

row_discard_tablespace(): Remove a bogus comment that seems to
refer to IMPORT TABLESPACE, not DISCARD TABLESPACE.

buf_flush_or_remove_pages(), buf_flush_dirty_pages(): Remove the
redundant parameter flush=(trx!=NULL).

  String comparison with utf8_bin collation is case sensitive.
  Hence "DELIMITER" did not match with "delimiter".
  The delimiter command matching now uses my_charset_latin1.